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1 files changed, 10446 insertions, 0 deletions

diff --git a/configs/shared/emacs/.emacs.d/elpa/flycheck-20180720.247/flycheck.el b/configs/shared/emacs/.emacs.d/elpa/flycheck-20180720.247/flycheck.el
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+;;; flycheck.el --- On-the-fly syntax checking -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017-2018 Flycheck contributors
+;; Copyright (C) 2012-2016 Sebastian Wiesner and Flycheck contributors
+;; Copyright (C) 2013, 2014 Free Software Foundation, Inc.
+;;
+;; Author: Sebastian Wiesner <swiesner@lunaryorn.com>
+;; Maintainer: Clément Pit-Claudel <clement.pitclaudel@live.com>
+;;             fmdkdd <fmdkdd@gmail.com>
+;; URL: http://www.flycheck.org
+;; Keywords: convenience, languages, tools
+;; Version: 32-cvs
+;; Package-Requires: ((dash "2.12.1") (pkg-info "0.4") (let-alist "1.0.4") (seq "1.11") (emacs "24.3"))
+
+;; This file is not part of GNU Emacs.
+
+;; This program is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; On-the-fly syntax checking for GNU Emacs 24.
+;;
+;; Flycheck is a modern on-the-fly syntax checking extension for GNU Emacs,
+;; intended as replacement for the older Flymake extension which is part of GNU
+;; Emacs.
+;;
+;; Flycheck automatically checks buffers for errors while you type, and reports
+;; warnings and errors directly in the buffer and in an optional IDE-like error
+;; list.
+;;
+;; It comes with a rich interface for custom syntax checkers and other
+;; extensions, and has already many 3rd party extensions adding new features.
+;;
+;; Please read the online manual at http://www.flycheck.org for more
+;; information.  You can open the manual directly from Emacs with `M-x
+;; flycheck-manual'.
+;;
+;; # Setup
+;;
+;; Flycheck works best on Unix systems.  It does not officially support Windows,
+;; but tries to maintain Windows compatibility and should generally work fine on
+;; Windows, too.
+;;
+;; To enable Flycheck add the following to your init file:
+;;
+;;    (add-hook 'after-init-hook #'global-flycheck-mode)
+;;
+;; Flycheck will then automatically check buffers in supported languages, as
+;; long as all necessary tools are present.  Use `flycheck-verify-setup' to
+;; troubleshoot your Flycheck setup.
+
+;;; Code:
+
+(eval-when-compile
+  (require 'let-alist)      ; `let-alist'
+  (require 'compile)        ; Compile Mode integration
+  (require 'jka-compr)      ; To inhibit compression of temp files
+  (require 'pcase)          ; `pcase-dolist' (`pcase' itself is autoloaded)
+  )
+
+(require 'dash)
+
+(require 'seq)                   ; Sequence functions
+(require 'subr-x nil 'no-error)  ; Additional utilities, Emacs 24.4 and upwards
+(require 'cl-lib)                ; `cl-defstruct' and CL utilities
+(require 'tabulated-list)        ; To list errors
+(require 'easymenu)              ; Flycheck Mode menu definition
+(require 'rx)                    ; Regexp fanciness in `flycheck-define-checker'
+(require 'help-mode)             ; `define-button-type'
+(require 'find-func)             ; `find-function-regexp-alist'
+(require 'json)                  ; `flycheck-parse-tslint'
+
+
+;; Declare a bunch of dynamic variables that we need from other modes
+(defvar sh-shell)                       ; For shell script checker predicates
+(defvar ess-language)                   ; For r-lintr predicate
+
+;; Tell the byte compiler about autoloaded functions from packages
+(declare-function pkg-info-version-info "pkg-info" (package))
+
+
+;;; Compatibility
+(eval-and-compile
+  (unless (fboundp 'string-suffix-p)
+    ;; TODO: Remove when dropping support for Emacs 24.3 and earlier
+    (defun string-suffix-p (suffix string &optional ignore-case)
+      "Return non-nil if SUFFIX is a suffix of STRING.
+If IGNORE-CASE is non-nil, the comparison is done without paying
+attention to case differences."
+      (let ((start-pos (- (length string) (length suffix))))
+        (and (>= start-pos 0)
+             (eq t (compare-strings suffix nil nil
+                                    string start-pos nil ignore-case))))))
+
+  ;; TODO: Remove when dropping support for Emacs 24.3 and earlier
+  (unless (featurep 'subr-x)
+    ;; `subr-x' function for Emacs 24.3 and below
+    (defsubst string-join (strings &optional separator)
+      "Join all STRINGS using SEPARATOR."
+      (mapconcat 'identity strings separator))
+
+    (defsubst string-trim-left (string)
+      "Remove leading whitespace from STRING."
+      (if (string-match "\\`[ \t\n\r]+" string)
+          (replace-match "" t t string)
+        string))
+
+    (defsubst string-trim-right (string)
+      "Remove trailing whitespace from STRING."
+      (if (string-match "[ \t\n\r]+\\'" string)
+          (replace-match "" t t string)
+        string))
+
+    (defsubst string-trim (string)
+      "Remove leading and trailing whitespace from STRING."
+      (string-trim-left (string-trim-right string)))
+
+    (defsubst string-empty-p (string)
+      "Check whether STRING is empty."
+      (string= string ""))))
+
+
+;;; Customization
+(defgroup flycheck nil
+  "Modern on-the-fly syntax checking for GNU Emacs."
+  :prefix "flycheck-"
+  :group 'tools
+  :link '(url-link :tag "Website" "http://www.flycheck.org")
+  :link '(url-link :tag "Github" "https://github.com/flycheck/flycheck"))
+
+(defgroup flycheck-config-files nil
+  "Configuration files for on-the-fly syntax checkers."
+  :prefix "flycheck-"
+  :group 'flycheck)
+
+(defgroup flycheck-options nil
+  "Options for on-the-fly syntax checkers."
+  :prefix "flycheck-"
+  :group 'flycheck)
+
+(defgroup flycheck-executables nil
+  "Executables of syntax checkers."
+  :prefix "flycheck-"
+  :group 'flycheck)
+
+(defgroup flycheck-faces nil
+  "Faces used by on-the-fly syntax checking."
+  :prefix "flycheck-"
+  :group 'flycheck)
+
+(defcustom flycheck-checkers
+  '(ada-gnat
+    asciidoctor
+    asciidoc
+    c/c++-clang
+    c/c++-gcc
+    c/c++-cppcheck
+    cfengine
+    chef-foodcritic
+    coffee
+    coffee-coffeelint
+    coq
+    css-csslint
+    css-stylelint
+    cwl
+    d-dmd
+    dockerfile-hadolint
+    emacs-lisp
+    emacs-lisp-checkdoc
+    erlang-rebar3
+    erlang
+    eruby-erubis
+    fortran-gfortran
+    go-gofmt
+    go-golint
+    go-vet
+    go-build
+    go-test
+    go-errcheck
+    go-unconvert
+    go-megacheck
+    groovy
+    haml
+    handlebars
+    haskell-stack-ghc
+    haskell-ghc
+    haskell-hlint
+    html-tidy
+    javascript-eslint
+    javascript-jshint
+    javascript-standard
+    json-jsonlint
+    json-python-json
+    jsonnet
+    less
+    less-stylelint
+    llvm-llc
+    lua-luacheck
+    lua
+    markdown-markdownlint-cli
+    markdown-mdl
+    nix
+    perl
+    perl-perlcritic
+    php
+    php-phpmd
+    php-phpcs
+    processing
+    proselint
+    protobuf-protoc
+    pug
+    puppet-parser
+    puppet-lint
+    python-flake8
+    python-pylint
+    python-pycompile
+    python-mypy
+    r-lintr
+    racket
+    rpm-rpmlint
+    rst-sphinx
+    rst
+    ruby-rubocop
+    ruby-reek
+    ruby-rubylint
+    ruby
+    ruby-jruby
+    rust-cargo
+    rust
+    rust-clippy
+    scala
+    scala-scalastyle
+    scheme-chicken
+    scss-lint
+    scss-stylelint
+    sass/scss-sass-lint
+    sass
+    scss
+    sh-bash
+    sh-posix-dash
+    sh-posix-bash
+    sh-zsh
+    sh-shellcheck
+    slim
+    slim-lint
+    sql-sqlint
+    systemd-analyze
+    tcl-nagelfar
+    tex-chktex
+    tex-lacheck
+    texinfo
+    typescript-tslint
+    verilog-verilator
+    vhdl-ghdl
+    xml-xmlstarlet
+    xml-xmllint
+    yaml-jsyaml
+    yaml-ruby)
+  "Syntax checkers available for automatic selection.
+
+A list of Flycheck syntax checkers to choose from when syntax
+checking a buffer.  Flycheck will automatically select a suitable
+syntax checker from this list, unless `flycheck-checker' is set,
+either directly or with `flycheck-select-checker'.
+
+You should not need to change this variable normally.  In order
+to disable syntax checkers, please use
+`flycheck-disabled-checkers'.  This variable is intended for 3rd
+party extensions to tell Flycheck about new syntax checkers.
+
+Syntax checkers in this list must be defined with
+`flycheck-define-checker'."
+  :group 'flycheck
+  :type '(repeat (symbol :tag "Checker"))
+  :risky t)
+
+(defcustom flycheck-disabled-checkers nil
+  "Syntax checkers excluded from automatic selection.
+
+A list of Flycheck syntax checkers to exclude from automatic
+selection.  Flycheck will never automatically select a syntax
+checker in this list, regardless of the value of
+`flycheck-checkers'.
+
+However, syntax checkers in this list are still available for
+manual selection with `flycheck-select-checker'.
+
+Use this variable to disable syntax checkers, instead of removing
+the syntax checkers from `flycheck-checkers'.  You may also use
+this option as a file or directory local variable to disable
+specific checkers in individual files and directories
+respectively."
+  :group 'flycheck
+  :type '(repeat (symbol :tag "Checker"))
+  :package-version '(flycheck . "0.16")
+  :safe #'flycheck-symbol-list-p)
+(make-variable-buffer-local 'flycheck-disabled-checkers)
+
+(defvar-local flycheck-checker nil
+  "Syntax checker to use for the current buffer.
+
+If unset or nil, automatically select a suitable syntax checker
+from `flycheck-checkers' on every syntax check.
+
+If set to a syntax checker only use this syntax checker and never
+select one from `flycheck-checkers' automatically.  The syntax
+checker is used regardless of whether it is contained in
+`flycheck-checkers' or `flycheck-disabled-checkers'.  If the
+syntax checker is unusable in the current buffer an error is
+signaled.
+
+A syntax checker assigned to this variable must be defined with
+`flycheck-define-checker'.
+
+Use the command `flycheck-select-checker' to select a syntax
+checker for the current buffer, or set this variable as file
+local variable to always use a specific syntax checker for a
+file.  See Info Node `(emacs)Specifying File Variables' for more
+information about file variables.")
+(put 'flycheck-checker 'safe-local-variable 'flycheck-registered-checker-p)
+
+(defcustom flycheck-locate-config-file-functions nil
+  "Functions to locate syntax checker configuration files.
+
+Each function in this hook must accept two arguments: The value
+of the configuration file variable, and the syntax checker
+symbol.  It must return either a string with an absolute path to
+the configuration file, or nil, if it cannot locate the
+configuration file.
+
+The functions in this hook are called in order of appearance, until a
+function returns non-nil.  The configuration file returned by that
+function is then given to the syntax checker if it exists.
+
+This variable is an abnormal hook.  See Info
+node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :risky t)
+
+(defcustom flycheck-checker-error-threshold 400
+  "Maximum errors allowed per syntax checker.
+
+The value of this variable is either an integer denoting the
+maximum number of errors per syntax checker and buffer, or nil to
+not limit the errors reported from a syntax checker.
+
+If this variable is a number and a syntax checker reports more
+errors than the value of this variable, its errors are not
+discarded, and not highlighted in the buffer or available in the
+error list.  The affected syntax checker is also disabled for
+future syntax checks of the buffer."
+  :group 'flycheck
+  :type '(choice (const :tag "Do not limit reported errors" nil)
+                 (integer :tag "Maximum number of errors"))
+  :risky t
+  :package-version '(flycheck . "0.22"))
+
+(defcustom flycheck-process-error-functions nil
+  "Functions to process errors.
+
+Each function in this hook must accept a single argument: A
+Flycheck error to process.
+
+All functions in this hook are called in order of appearance,
+until a function returns non-nil.  Thus, a function in this hook
+may return nil, to allow for further processing of the error, or
+any non-nil value, to indicate that the error was fully processed
+and inhibit any further processing.
+
+The functions are called for each newly parsed error immediately
+after the corresponding syntax checker finished.  At this stage,
+the overlays from the previous syntax checks are still present,
+and there may be further syntax checkers in the chain.
+
+This variable is an abnormal hook.  See Info
+node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :package-version '(flycheck . "0.13")
+  :risky t)
+
+(defcustom flycheck-display-errors-delay 0.9
+  "Delay in seconds before displaying errors at point.
+
+Use floating point numbers to express fractions of seconds."
+  :group 'flycheck
+  :type 'number
+  :package-version '(flycheck . "0.15")
+  :safe #'numberp)
+
+(defcustom flycheck-display-errors-function #'flycheck-display-error-messages
+  "Function to display error messages.
+
+If set to a function, call the function with the list of errors
+to display as single argument.  Each error is an instance of the
+`flycheck-error' struct.
+
+If set to nil, do not display errors at all."
+  :group 'flycheck
+  :type '(choice (const :tag "Display error messages"
+                        flycheck-display-error-messages)
+                 (const :tag "Display error messages only if no error list"
+                        flycheck-display-error-messages-unless-error-list)
+                 (function :tag "Error display function"))
+  :package-version '(flycheck . "0.13")
+  :risky t)
+
+(defcustom flycheck-help-echo-function #'flycheck-help-echo-all-error-messages
+  "Function to compute the contents of the error tooltips.
+
+If set to a function, call the function with the list of errors
+to display as single argument.  Each error is an instance of the
+`flycheck-error' struct.  The function is used to set the
+help-echo property of flycheck error overlays.  It should return
+a string, which is displayed when the user hovers over an error
+or presses \\[display-local-help].
+
+If set to nil, do not show error tooltips."
+  :group 'flycheck
+  :type '(choice (const :tag "Concatenate error messages to form a tooltip"
+                        flycheck-help-echo-all-error-messages)
+                 (function :tag "Help echo function"))
+  :package-version '(flycheck . "0.25")
+  :risky t)
+
+(defcustom flycheck-command-wrapper-function #'identity
+  "Function to modify checker commands before execution.
+
+The value of this option is a function which is given a list
+containing the full command of a syntax checker after
+substitution through `flycheck-substitute-argument' but before
+execution.  The function may return a new command for Flycheck to
+execute.
+
+The default value is `identity' which does not change the
+command.  You may provide your own function to run Flycheck
+commands through `bundle exec', `nix-shell' or similar wrappers."
+  :group 'flycheck
+  :type '(choice (const :tag "Do not modify commands" identity)
+                 (function :tag "Modify command with a custom function"))
+  :package-version '(flycheck . "0.25")
+  :risky t)
+
+(defcustom flycheck-executable-find #'executable-find
+  "Function to search for executables.
+
+The value of this option is a function which is given the name or
+path of an executable and shall return the full path to the
+executable, or nil if the executable does not exit.
+
+The default is the standard `executable-find' function which
+searches `exec-path'.  You can customize this option to search
+for checkers in other environments such as bundle or NixOS
+sandboxes."
+  :group 'flycheck
+  :type '(choice
+          (const :tag "Search executables in `exec-path'" executable-find)
+          (function :tag "Search executables with a custom function"))
+  :package-version '(flycheck . "0.25")
+  :risky t)
+
+(defcustom flycheck-indication-mode 'left-fringe
+  "The indication mode for Flycheck errors and warnings.
+
+This variable controls how Flycheck indicates errors in buffers.
+May either be `left-fringe', `right-fringe', or nil.
+
+If set to `left-fringe' or `right-fringe', indicate errors and
+warnings via icons in the left and right fringe respectively.
+
+If set to nil, do not indicate errors and warnings, but just
+highlight them according to `flycheck-highlighting-mode'."
+  :group 'flycheck
+  :type '(choice (const :tag "Indicate in the left fringe" left-fringe)
+                 (const :tag "Indicate in the right fringe" right-fringe)
+                 (const :tag "Do not indicate" nil))
+  :safe #'symbolp)
+
+(defcustom flycheck-highlighting-mode 'symbols
+  "The highlighting mode for Flycheck errors and warnings.
+
+The highlighting mode controls how Flycheck highlights errors in
+buffers.  The following modes are known:
+
+`columns'
+     Highlight the error column.  If the error does not have a column,
+     highlight the whole line.
+
+`symbols'
+     Highlight the symbol at the error column, if there is any,
+     otherwise behave like `columns'.  This is the default.
+
+`sexps'
+     Highlight the expression at the error column, if there is
+     any, otherwise behave like `columns'.  Note that this mode
+     can be *very* slow in some major modes.
+
+`lines'
+     Highlight the whole line.
+
+nil
+     Do not highlight errors at all.  However, errors will still
+     be reported in the mode line and in error message popups,
+     and indicated according to `flycheck-indication-mode'."
+  :group 'flycheck
+  :type '(choice (const :tag "Highlight columns only" columns)
+                 (const :tag "Highlight symbols" symbols)
+                 (const :tag "Highlight expressions" sexps)
+                 (const :tag "Highlight whole lines" lines)
+                 (const :tag "Do not highlight errors" nil))
+  :package-version '(flycheck . "0.14")
+  :safe #'symbolp)
+
+(defcustom flycheck-check-syntax-automatically '(save
+                                                 idle-change
+                                                 new-line
+                                                 mode-enabled)
+  "When Flycheck should check syntax automatically.
+
+This variable is a list of events that may trigger syntax checks.
+The following events are known:
+
+`save'
+     Check syntax immediately after the buffer was saved.
+
+`idle-change'
+     Check syntax a short time (see `flycheck-idle-change-delay')
+     after the last change to the buffer.
+
+`new-line'
+     Check syntax immediately after a new line was inserted into
+     the buffer.
+
+`mode-enabled'
+     Check syntax immediately when variable `flycheck-mode' is
+     non-nil.
+
+Flycheck performs a syntax checks only on events, which are
+contained in this list.  For instance, if the value of this
+variable is `(mode-enabled save)', Flycheck will only check if
+the mode is enabled or the buffer was saved, but never after
+changes to the buffer contents.
+
+If nil, never check syntax automatically.  In this case, use
+`flycheck-buffer' to start a syntax check manually."
+  :group 'flycheck
+  :type '(set (const :tag "After the buffer was saved" save)
+              (const :tag "After the buffer was changed and idle" idle-change)
+              (const :tag "After a new line was inserted" new-line)
+              (const :tag "After `flycheck-mode' was enabled" mode-enabled))
+  :package-version '(flycheck . "0.12")
+  :safe #'flycheck-symbol-list-p)
+
+(defcustom flycheck-idle-change-delay 0.5
+  "How many seconds to wait before checking syntax automatically.
+
+After the buffer was changed, Flycheck will wait as many seconds
+as the value of this variable before starting a syntax check.  If
+the buffer is modified during this time, Flycheck will wait
+again.
+
+This variable has no effect, if `idle-change' is not contained in
+`flycheck-check-syntax-automatically'."
+  :group 'flycheck
+  :type 'number
+  :package-version '(flycheck . "0.13")
+  :safe #'numberp)
+
+(defcustom flycheck-standard-error-navigation t
+  "Whether to support error navigation with `next-error'.
+
+If non-nil, enable navigation of Flycheck errors with
+`next-error', `previous-error' and `first-error'.  Otherwise,
+these functions just navigate errors from compilation modes.
+
+Flycheck error navigation with `flycheck-next-error',
+`flycheck-previous-error' and `flycheck-first-error' is always
+enabled, regardless of the value of this variable.
+
+Note that this setting only takes effect when variable
+`flycheck-mode' is non-nil.  Changing it will not affect buffers
+where variable `flycheck-mode' is already non-nil."
+  :group 'flycheck
+  :type 'boolean
+  :package-version '(flycheck . "0.15")
+  :safe #'booleanp)
+
+(define-widget 'flycheck-minimum-level 'lazy
+  "A radio-type choice of minimum error levels.
+
+See `flycheck-navigation-minimum-level' and
+`flycheck-error-list-minimum-level'."
+  :type '(radio (const :tag "All locations" nil)
+                (const :tag "Informational messages" info)
+                (const :tag "Warnings" warning)
+                (const :tag "Errors" error)
+                (symbol :tag "Custom error level")))
+
+(defcustom flycheck-navigation-minimum-level nil
+  "The minimum level of errors to navigate.
+
+If set to an error level, only navigate errors whose error level
+is at least as severe as this one.  If nil, navigate all errors."
+  :group 'flycheck
+  :type 'flycheck-minimum-level
+  :safe #'flycheck-error-level-p
+  :package-version '(flycheck . "0.21"))
+
+(defcustom flycheck-error-list-minimum-level nil
+  "The minimum level of errors to display in the error list.
+
+If set to an error level, only display errors whose error level
+is at least as severe as this one in the error list.  If nil,
+display all errors.
+
+This is the default level, used when the error list is opened.
+You can temporarily change the level using
+\\[flycheck-error-list-set-filter], or reset it to this value
+using \\[flycheck-error-list-reset-filter]."
+  :group 'flycheck
+  :type 'flycheck-minimum-level
+  :safe #'flycheck-error-level-p
+  :package-version '(flycheck . "0.24"))
+
+(defcustom flycheck-completing-read-function #'completing-read
+  "Function to read from minibuffer with completion.
+
+The function must be compatible to the built-in `completing-read'
+function."
+  :group 'flycheck
+  :type '(choice (const :tag "Default" completing-read)
+                 (const :tag "IDO" ido-completing-read)
+                 (function :tag "Custom function"))
+  :risky t
+  :package-version '(flycheck . "26"))
+
+(defcustom flycheck-temp-prefix "flycheck"
+  "Prefix for temporary files created by Flycheck."
+  :group 'flycheck
+  :type 'string
+  :package-version '(flycheck . "0.19")
+  :risky t)
+
+(defcustom flycheck-mode-hook nil
+  "Hooks to run after command `flycheck-mode' is toggled."
+  :group 'flycheck
+  :type 'hook
+  :risky t)
+
+(defcustom flycheck-after-syntax-check-hook nil
+  "Functions to run after each syntax check.
+
+This hook is run after a syntax check was finished.
+
+At this point, *all* chained checkers were run, and all errors
+were parsed, highlighted and reported.  The variable
+`flycheck-current-errors' contains all errors from all syntax
+checkers run during the syntax check, so you can apply any error
+analysis functions.
+
+Note that this hook does *not* run after each individual syntax
+checker in the syntax checker chain, but only after the *last
+checker*.
+
+This variable is a normal hook.  See Info node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :risky t)
+
+(defcustom flycheck-before-syntax-check-hook nil
+  "Functions to run before each syntax check.
+
+This hook is run right before a syntax check starts.
+
+Error information from the previous syntax check is *not*
+cleared before this hook runs.
+
+Note that this hook does *not* run before each individual syntax
+checker in the syntax checker chain, but only before the *first
+checker*.
+
+This variable is a normal hook.  See Info node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :risky t)
+
+(defcustom flycheck-syntax-check-failed-hook nil
+  "Functions to run if a syntax check failed.
+
+This hook is run whenever an error occurs during Flycheck's
+internal processing.  No information about the error is given to
+this hook.
+
+You should use this hook to conduct additional cleanup actions
+when Flycheck failed.
+
+This variable is a normal hook.  See Info node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :risky t)
+
+(defcustom flycheck-status-changed-functions nil
+  "Functions to run if the Flycheck status changed.
+
+This hook is run whenever the status of Flycheck changes.  Each
+hook function takes the status symbol as single argument, as
+given to `flycheck-report-status', which see.
+
+This variable is an abnormal hook.  See Info
+node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :risky t
+  :package-version '(flycheck . "0.20"))
+
+(defcustom flycheck-error-list-after-refresh-hook nil
+  "Functions to run after the error list was refreshed.
+
+This hook is run whenever the error list is refreshed.
+
+This variable is a normal hook.  See Info node `(elisp)Hooks'."
+  :group 'flycheck
+  :type 'hook
+  :risky t
+  :package-version '(flycheck . "0.21"))
+
+(defface flycheck-error
+  '((((supports :underline (:style wave)))
+     :underline (:style wave :color "Red1"))
+    (t
+     :underline t :inherit error))
+  "Flycheck face for errors."
+  :package-version '(flycheck . "0.13")
+  :group 'flycheck-faces)
+
+(defface flycheck-warning
+  '((((supports :underline (:style wave)))
+     :underline (:style wave :color "DarkOrange"))
+    (t
+     :underline t :inherit warning))
+  "Flycheck face for warnings."
+  :package-version '(flycheck . "0.13")
+  :group 'flycheck-faces)
+
+(defface flycheck-info
+  '((((supports :underline (:style wave)))
+     :underline (:style wave :color "ForestGreen"))
+    (t
+     :underline t :inherit success))
+  "Flycheck face for informational messages."
+  :package-version '(flycheck . "0.15")
+  :group 'flycheck-faces)
+
+(defface flycheck-fringe-error
+  '((t :inherit error))
+  "Flycheck face for fringe error indicators."
+  :package-version '(flycheck . "0.13")
+  :group 'flycheck-faces)
+
+(defface flycheck-fringe-warning
+  '((t :inherit warning))
+  "Flycheck face for fringe warning indicators."
+  :package-version '(flycheck . "0.13")
+  :group 'flycheck-faces)
+
+(defface flycheck-fringe-info
+  ;; Semantically `success' is probably not the right face, but it looks nice as
+  ;; a base face
+  '((t :inherit success))
+  "Flycheck face for fringe info indicators."
+  :package-version '(flycheck . "0.15")
+  :group 'flycheck-faces)
+
+(defface flycheck-error-list-error
+  '((t :inherit error))
+  "Flycheck face for error messages in the error list."
+  :package-version '(flycheck . "0.16")
+  :group 'flycheck-faces)
+
+(defface flycheck-error-list-warning
+  '((t :inherit warning))
+  "Flycheck face for warning messages in the error list."
+  :package-version '(flycheck . "0.16")
+  :group 'flycheck-faces)
+
+(defface flycheck-error-list-info
+  '((t :inherit success))
+  "Flycheck face for info messages in the error list."
+  :package-version '(flycheck . "0.16")
+  :group 'flycheck-faces)
+
+;; The base faces for the following two faces are inspired by Compilation Mode
+(defface flycheck-error-list-line-number
+  '((t :inherit font-lock-constant-face))
+  "Face for line numbers in the error list."
+  :group 'flycheck-faces
+  :package-version '(flycheck . "0.16"))
+
+(defface flycheck-error-list-column-number
+  '((t :inherit font-lock-constant-face))
+  "Face for line numbers in the error list."
+  :group 'flycheck-faces
+  :package-version '(flycheck . "0.16"))
+
+(defface flycheck-error-list-filename
+  '((t :inherit font-lock-variable-name-face))
+  "Face for filenames in the error list."
+  :group 'flycheck-faces
+  :package-version '(flycheck . "32"))
+
+(defface flycheck-error-list-id
+  '((t :inherit font-lock-type-face))
+  "Face for the error ID in the error list."
+  :group 'flycheck-faces
+  :package-version '(flycheck . "0.22"))
+
+(defface flycheck-error-list-id-with-explainer
+  '((t :inherit flycheck-error-list-id
+       :box (:style released-button)))
+  "Face for the error ID in the error list, for errors that have an explainer."
+  :group 'flycheck-faces
+  :package-version '(flycheck . "30"))
+
+(defface flycheck-error-list-checker-name
+  '((t :inherit font-lock-function-name-face))
+  "Face for the syntax checker name in the error list."
+  :group 'flycheck-faces
+  :package-version '(flycheck . "0.21"))
+
+(defface flycheck-error-list-highlight
+  '((t :inherit highlight))
+  "Flycheck face to highlight errors in the error list."
+  :package-version '(flycheck . "0.15")
+  :group 'flycheck-faces)
+
+(defvar flycheck-command-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map "c"         #'flycheck-buffer)
+    (define-key map "C"         #'flycheck-clear)
+    (define-key map (kbd "C-c") #'flycheck-compile)
+    (define-key map "n"         #'flycheck-next-error)
+    (define-key map "p"         #'flycheck-previous-error)
+    (define-key map "l"         #'flycheck-list-errors)
+    (define-key map (kbd "C-w") #'flycheck-copy-errors-as-kill)
+    (define-key map "s"         #'flycheck-select-checker)
+    (define-key map "?"         #'flycheck-describe-checker)
+    (define-key map "h"         #'flycheck-display-error-at-point)
+    (define-key map "e"         #'flycheck-explain-error-at-point)
+    (define-key map "H"         #'display-local-help)
+    (define-key map "i"         #'flycheck-manual)
+    (define-key map "V"         #'flycheck-version)
+    (define-key map "v"         #'flycheck-verify-setup)
+    (define-key map "x"         #'flycheck-disable-checker)
+    map)
+  "Keymap of Flycheck interactive commands.")
+
+(defcustom flycheck-keymap-prefix (kbd "C-c !")
+  "Prefix for key bindings of Flycheck.
+
+Changing this variable outside Customize does not have any
+effect.  To change the keymap prefix from Lisp, you need to
+explicitly re-define the prefix key:
+
+    (define-key flycheck-mode-map flycheck-keymap-prefix nil)
+    (setq flycheck-keymap-prefix (kbd \"C-c f\"))
+    (define-key flycheck-mode-map flycheck-keymap-prefix
+                flycheck-command-map)
+
+Please note that Flycheck's manual documents the default
+keybindings.  Changing this variable is at your own risk."
+  :group 'flycheck
+  :package-version '(flycheck . "0.19")
+  :type 'string
+  :risky t
+  :set
+  (lambda (variable key)
+    (when (and (boundp variable) (boundp 'flycheck-mode-map))
+      (define-key flycheck-mode-map (symbol-value variable) nil)
+      (define-key flycheck-mode-map key flycheck-command-map))
+    (set-default variable key)))
+
+(defcustom flycheck-mode-line '(:eval (flycheck-mode-line-status-text))
+  "Mode line lighter for Flycheck.
+
+The value of this variable is a mode line template as in
+`mode-line-format'.  See Info Node `(elisp)Mode Line Format' for
+more information.  Note that it should contain a _single_ mode
+line construct only.
+
+Customize this variable to change how Flycheck reports its status
+in the mode line.  You may use `flycheck-mode-line-status-text'
+to obtain a human-readable status text, including an
+error/warning count.
+
+You may also assemble your own status text.  The current status
+of Flycheck is available in `flycheck-last-status-change'.  The
+errors in the current buffer are stored in
+`flycheck-current-errors', and the function
+`flycheck-count-errors' may be used to obtain the number of
+errors grouped by error level.
+
+Set this variable to nil to disable the mode line completely."
+  :group 'flycheck
+  :type 'sexp
+  :risky t
+  :package-version '(flycheck . "0.20"))
+
+(defcustom flycheck-mode-line-prefix "FlyC"
+  "Base mode line lighter for Flycheck.
+
+This will have an effect only with the default
+`flycheck-mode-line'.
+
+If you've customized `flycheck-mode-line' then the customized
+function must be updated to use this variable."
+  :group 'flycheck
+  :type 'string
+  :package-version '(flycheck . "26"))
+
+(defcustom flycheck-error-list-mode-line
+  `(,(propertized-buffer-identification "%12b")
+    " for buffer "
+    (:eval (flycheck-error-list-propertized-source-name))
+    (:eval (flycheck-error-list-mode-line-filter-indicator)))
+  "Mode line construct for Flycheck error list.
+
+The value of this variable is a mode line template as in
+`mode-line-format', to be used as
+`mode-line-buffer-identification' in `flycheck-error-list-mode'.
+See Info Node `(elisp)Mode Line Format' for more information.
+
+Customize this variable to change how the error list appears in
+the mode line.  The default shows the name of the buffer and the
+name of the source buffer, i.e. the buffer whose errors are
+currently listed."
+  :group 'flycheck
+  :type 'sexp
+  :risky t
+  :package-version '(flycheck . "0.20"))
+
+(defcustom flycheck-global-modes t
+  "Modes for which option `flycheck-mode' is turned on.
+
+If t, Flycheck Mode is turned on for all major modes.  If a list,
+Flycheck Mode is turned on for all `major-mode' symbols in that
+list.  If the `car' of the list is `not', Flycheck Mode is turned
+on for all `major-mode' symbols _not_ in that list.  If nil,
+Flycheck Mode is never turned on by command
+`global-flycheck-mode'.
+
+Note that Flycheck is never turned on for modes whose
+`mode-class' property is `special' (see Info node `(elisp)Major
+Mode Conventions'), regardless of the value of this option.
+
+Only has effect when variable `global-flycheck-mode' is non-nil."
+  :group 'flycheck
+  :type '(choice (const :tag "none" nil)
+                 (const :tag "all" t)
+                 (set :menu-tag "mode specific" :tag "modes"
+                      :value (not)
+                      (const :tag "Except" not)
+                      (repeat :inline t (symbol :tag "mode"))))
+  :risky t
+  :package-version '(flycheck . "0.23"))
+
+;; Add built-in functions to our hooks, via `add-hook', to make sure that our
+;; functions are really present, even if the variable was implicitly defined by
+;; another call to `add-hook' that occurred before Flycheck was loaded.  See
+;; http://lists.gnu.org/archive/html/emacs-devel/2015-02/msg01271.html for why
+;; we don't initialize the hook variables right away.  We append our own
+;; functions, because a user likely expects that their functions come first,
+;; even if the added them before Flycheck was loaded.
+(dolist (hook (list #'flycheck-locate-config-file-by-path
+                    #'flycheck-locate-config-file-ancestor-directories
+                    #'flycheck-locate-config-file-home))
+  (add-hook 'flycheck-locate-config-file-functions hook 'append))
+
+(add-hook 'flycheck-process-error-functions #'flycheck-add-overlay 'append)
+
+
+;;; Global Flycheck menu
+(defvar flycheck-mode-menu-map
+  (easy-menu-create-menu
+   "Syntax Checking"
+   '(["Enable on-the-fly syntax checking" flycheck-mode
+      :style toggle :selected flycheck-mode
+      :enable (or flycheck-mode
+                  ;; Don't let users toggle the mode if there is no syntax
+                  ;; checker for this buffer
+                  (seq-find #'flycheck-checker-supports-major-mode-p
+                            flycheck-checkers))]
+     ["Check current buffer" flycheck-buffer flycheck-mode]
+     ["Clear errors in buffer" flycheck-clear t]
+     "---"
+     ["Go to next error" flycheck-next-error flycheck-mode]
+     ["Go to previous error" flycheck-previous-error flycheck-mode]
+     ["Show all errors" flycheck-list-errors flycheck-mode]
+     "---"
+     ["Copy messages at point" flycheck-copy-errors-as-kill
+      (flycheck-overlays-at (point))]
+     ["Explain error at point" flycheck-explain-error-at-point]
+     "---"
+     ["Select syntax checker" flycheck-select-checker flycheck-mode]
+     ["Disable syntax checker" flycheck-disable-checker flycheck-mode]
+     ["Set executable of syntax checker" flycheck-set-checker-executable
+      flycheck-mode]
+     "---"
+     ["Describe syntax checker" flycheck-describe-checker t]
+     ["Show Flycheck version" flycheck-version t]
+     ["Read the Flycheck manual" flycheck-info t]))
+  "Menu of command `flycheck-mode'.")
+
+(easy-menu-add-item nil '("Tools") flycheck-mode-menu-map "Spell Checking")
+
+
+;;; Version information, manual and loading of Flycheck
+(defun flycheck-version (&optional show-version)
+  "Get the Flycheck version as string.
+
+If called interactively or if SHOW-VERSION is non-nil, show the
+version in the echo area and the messages buffer.
+
+The returned string includes both, the version from package.el
+and the library version, if both a present and different.
+
+If the version number could not be determined, signal an error,
+if called interactively, or if SHOW-VERSION is non-nil, otherwise
+just return nil."
+  (interactive (list t))
+  (let ((version (pkg-info-version-info 'flycheck)))
+    (when show-version
+      (message "Flycheck version: %s" version))
+    version))
+
+(defun flycheck-unload-function ()
+  "Unload function for Flycheck."
+  (global-flycheck-mode -1)
+  (easy-menu-remove-item nil '("Tools") (cadr flycheck-mode-menu-map))
+  (remove-hook 'kill-emacs-hook #'flycheck-global-teardown)
+  (setq find-function-regexp-alist
+        (assq-delete-all 'flycheck-checker find-function-regexp-alist)))
+
+;;;###autoload
+(defun flycheck-manual ()
+  "Open the Flycheck manual."
+  (interactive)
+  (browse-url "http://www.flycheck.org"))
+
+(define-obsolete-function-alias 'flycheck-info
+  'flycheck-manual "26" "Open the Flycheck manual.")
+
+
+;;; Utility functions
+(defun flycheck-sexp-to-string (sexp)
+  "Convert SEXP to a string.
+
+Like `prin1-to-string' but ensure that the returned string
+is loadable."
+  (let ((print-quoted t)
+        (print-length nil)
+        (print-level nil))
+    (prin1-to-string sexp)))
+
+(defun flycheck-string-to-number-safe (string)
+  "Safely convert STRING to a number.
+
+If STRING is of string type and a numeric string, convert STRING
+to a number and return it.  Otherwise return nil."
+  (let ((number-re (rx string-start (one-or-more (any digit)) string-end)))
+    (when (and (stringp string) (string-match-p number-re string))
+      (string-to-number string))))
+
+(defun flycheck-string-list-p (obj)
+  "Determine if OBJ is a list of strings."
+  (and (listp obj) (seq-every-p #'stringp obj)))
+
+(defun flycheck-symbol-list-p (obj)
+  "Determine if OBJ is a list of symbols."
+  (and (listp obj) (seq-every-p #'symbolp obj)))
+
+(defun flycheck-same-files-p (file-a file-b)
+  "Determine whether FILE-A and FILE-B refer to the same file."
+  (let ((file-a (expand-file-name file-a))
+        (file-b (expand-file-name file-b)))
+    ;; We must resolve symbolic links here, since some syntax checker always
+    ;; output canonical file names with all symbolic links resolved.  However,
+    ;; we still do a simple path compassion first, to avoid the comparatively
+    ;; expensive file system call if possible.  See
+    ;; https://github.com/flycheck/flycheck/issues/561
+    (or (string= (directory-file-name file-a) (directory-file-name file-b))
+        (string= (directory-file-name (file-truename file-a))
+                 (directory-file-name (file-truename file-b))))))
+
+(defvar-local flycheck-temporaries nil
+  "Temporary files and directories created by Flycheck.")
+
+(defun flycheck-temp-dir-system ()
+  "Create a unique temporary directory.
+
+Use `flycheck-temp-prefix' as prefix, and add the directory to
+`flycheck-temporaries'.
+
+Return the path of the directory"
+  (let* ((tempdir (make-temp-file flycheck-temp-prefix 'directory)))
+    (push tempdir flycheck-temporaries)
+    tempdir))
+
+(defun flycheck-temp-file-system (filename)
+  "Create a temporary file named after FILENAME.
+
+If FILENAME is non-nil, this function creates a temporary
+directory with `flycheck-temp-dir-system', and creates a file
+with the same name as FILENAME in this directory.
+
+Otherwise this function creates a temporary file with
+`flycheck-temp-prefix' and a random suffix.  The path of the file
+is added to `flycheck-temporaries'.
+
+Return the path of the file."
+  (let ((tempfile (convert-standard-filename
+                   (if filename
+                       (expand-file-name (file-name-nondirectory filename)
+                                         (flycheck-temp-dir-system))
+                     (make-temp-file flycheck-temp-prefix)))))
+    (push tempfile flycheck-temporaries)
+    tempfile))
+
+(defun flycheck-temp-file-inplace (filename)
+  "Create an in-place copy of FILENAME.
+
+Prefix the file with `flycheck-temp-prefix' and add the path of
+the file to `flycheck-temporaries'.
+
+If FILENAME is nil, fall back to `flycheck-temp-file-system'.
+
+Return the path of the file."
+  (if filename
+      (let* ((tempname (format "%s_%s"
+                               flycheck-temp-prefix
+                               (file-name-nondirectory filename)))
+             (tempfile (convert-standard-filename
+                        (expand-file-name tempname
+                                          (file-name-directory filename)))))
+        (push tempfile flycheck-temporaries)
+        tempfile)
+    (flycheck-temp-file-system filename)))
+
+(defun flycheck-temp-directory (checker)
+  "Return the directory where CHECKER writes temporary files.
+
+Return nil if the CHECKER does not write temporary files."
+  (let ((args (flycheck-checker-arguments checker)))
+    (cond
+     ((memq 'source args) temporary-file-directory)
+     ((memq 'source-inplace args)
+      (if buffer-file-name (file-name-directory buffer-file-name)
+        temporary-file-directory))
+     (t nil))))
+
+(defun flycheck-temp-files-writable-p (checker)
+  "Whether CHECKER can write temporary files.
+
+If CHECKER has `source' or `source-inplace' in its `:command',
+return whether flycheck has the permissions to create the
+respective temporary files.
+
+Return t if CHECKER does not use temporary files."
+  (let ((dir (flycheck-temp-directory checker)))
+    (or (not dir) (file-writable-p dir))))
+
+(defun flycheck-save-buffer-to-file (file-name)
+  "Save the contents of the current buffer to FILE-NAME."
+  (make-directory (file-name-directory file-name) t)
+  (let ((jka-compr-inhibit t))
+    (write-region nil nil file-name nil 0)))
+
+(defun flycheck-save-buffer-to-temp (temp-file-fn)
+  "Save buffer to temp file returned by TEMP-FILE-FN.
+
+Return the name of the temporary file."
+  (let ((filename (funcall temp-file-fn (buffer-file-name))))
+    ;; Do not flush short-lived temporary files onto disk
+    (let ((write-region-inhibit-fsync t))
+      (flycheck-save-buffer-to-file filename))
+    filename))
+
+(defun flycheck-prepend-with-option (option items &optional prepend-fn)
+  "Prepend OPTION to each item in ITEMS, using PREPEND-FN.
+
+Prepend OPTION to each item in ITEMS.
+
+ITEMS is a list of strings to pass to the syntax checker.  OPTION
+is the option, as string.  PREPEND-FN is a function called to
+prepend OPTION to each item in ITEMS.  It receives the option and
+a single item from ITEMS as argument, and must return a string or
+a list of strings with OPTION prepended to the item.  If
+PREPEND-FN is nil or omitted, use `list'.
+
+Return a list of strings where OPTION is prepended to each item
+in ITEMS using PREPEND-FN.  If PREPEND-FN returns a list, it is
+spliced into the resulting list."
+  (unless (stringp option)
+    (error "Option %S is not a string" option))
+  (unless prepend-fn
+    (setq prepend-fn #'list))
+  (let ((prepend
+         (lambda (item)
+           (let ((result (funcall prepend-fn option item)))
+             (cond
+              ((and (listp result) (seq-every-p #'stringp result)) result)
+              ((stringp result) (list result))
+              (t (error "Invalid result type for option: %S" result)))))))
+    (apply #'append (seq-map prepend items))))
+
+(defun flycheck-find-in-buffer (pattern)
+  "Find PATTERN in the current buffer.
+
+Return the result of the first matching group of PATTERN, or nil,
+if PATTERN did not match."
+  (save-restriction
+    (widen)
+    (save-excursion
+      (goto-char (point-min))
+      (when (re-search-forward pattern nil 'no-error)
+        (match-string-no-properties 1)))))
+
+(defun flycheck-buffer-empty-p (&optional buffer)
+  "Whether a BUFFER is empty.
+
+If buffer is nil or omitted check the current buffer.
+
+Return non-nil if so, or nil if the buffer has content."
+  (<= (buffer-size buffer) 0))
+
+(defun flycheck-ephemeral-buffer-p ()
+  "Determine whether the current buffer is an ephemeral buffer.
+
+See Info node `(elisp)Buffer Names' for information about
+ephemeral buffers."
+  (string-prefix-p " " (buffer-name)))
+
+(defun flycheck-encrypted-buffer-p ()
+  "Determine whether the current buffer is an encrypted file.
+
+See Info node `(epa)Top' for Emacs' interface to encrypted
+files."
+  ;; The EPA file handler sets this variable locally to remember the recipients
+  ;; of the encrypted file for re-encryption.  Hence, a local binding of this
+  ;; variable is a good indication that the buffer is encrypted.  I haven't
+  ;; found any better indicator anyway.
+  (local-variable-p 'epa-file-encrypt-to))
+
+(defun flycheck-autoloads-file-p ()
+  "Determine whether the current buffer is an autoloads file.
+
+Autoloads are generated by package.el during installation."
+  (string-suffix-p "-autoloads.el" (buffer-name)))
+
+(defun flycheck-in-user-emacs-directory-p (filename)
+  "Whether FILENAME is in `user-emacs-directory'."
+  (string-prefix-p (file-name-as-directory (file-truename user-emacs-directory))
+                   (file-truename filename)))
+
+(defun flycheck-safe-delete (file-or-dir)
+  "Safely delete FILE-OR-DIR."
+  (ignore-errors
+    (if (file-directory-p file-or-dir)
+        (delete-directory file-or-dir 'recursive)
+      (delete-file file-or-dir))))
+
+(defun flycheck-safe-delete-temporaries ()
+  "Safely delete all temp files and directories of Flycheck.
+
+Safely delete all files and directories listed in
+`flycheck-temporaries' and set the variable's value to nil."
+  (seq-do #'flycheck-safe-delete flycheck-temporaries)
+  (setq flycheck-temporaries nil))
+
+(defun flycheck-rx-file-name (form)
+  "Translate the `(file-name)' FORM into a regular expression."
+  (let ((body (or (cdr form) '((minimal-match
+                                (one-or-more not-newline))))))
+    (rx-submatch-n `(group-n 1 ,@body))))
+
+(defun flycheck-rx-message (form)
+  "Translate the `(message)' FORM into a regular expression."
+  (let ((body (or (cdr form) '((one-or-more not-newline)))))
+    (rx-submatch-n `(group-n 4 ,@body))))
+
+(defun flycheck-rx-id (form)
+  "Translate the `(id)' FORM into a regular expression."
+  (rx-submatch-n `(group-n 5 ,@(cdr form))))
+
+(defun flycheck-rx-to-string (form &optional no-group)
+  "Like `rx-to-string' for FORM, but with special keywords:
+
+`line'
+     matches the line number.
+
+`column'
+     matches the column number.
+
+`(file-name SEXP ...)'
+     matches the file name.  SEXP describes the file name.  If no
+     SEXP is given, use a default body of `(minimal-match
+     (one-or-more not-newline))'.
+
+`(message SEXP ...)'
+     matches the message.  SEXP constitutes the body of the
+     message.  If no SEXP is given, use a default body
+     of `(one-or-more not-newline)'.
+
+`(id SEXP ...)'
+     matches an error ID.  SEXP describes the ID.
+
+NO-GROUP is passed to `rx-to-string'.
+
+See `rx' for a complete list of all built-in `rx' forms."
+  (let ((rx-constituents
+         (append
+          `((line . ,(rx (group-n 2 (one-or-more digit))))
+            (column . ,(rx (group-n 3 (one-or-more digit))))
+            (file-name flycheck-rx-file-name 0 nil)
+            (message flycheck-rx-message 0 nil)
+            (id flycheck-rx-id 0 nil))
+          rx-constituents nil)))
+    (rx-to-string form no-group)))
+
+(defun flycheck-current-load-file ()
+  "Get the source file currently being loaded.
+
+Always return the name of the corresponding source file, never
+any byte-compiled file.
+
+Return nil, if the currently loaded file cannot be determined."
+  (-when-let* ((this-file (cond
+                           (load-in-progress load-file-name)
+                           ((bound-and-true-p byte-compile-current-file))
+                           (t (buffer-file-name))))
+               ;; A best guess for the source file of a compiled library. Works
+               ;; well in most cases, and especially for ELPA packages
+               (source-file (concat (file-name-sans-extension this-file)
+                                    ".el")))
+    (when (file-exists-p source-file)
+      source-file)))
+
+(defun flycheck-module-root-directory (module &optional file-name)
+  "Get the root directory for a MODULE in FILE-NAME.
+
+MODULE is a qualified module name, either a string with
+components separated by a dot, or as list of components.
+FILE-NAME is the name of the file or directory containing the
+module as string.  When nil or omitted, defaults to the return
+value of function `buffer-file-name'.
+
+Return the root directory of the module, that is, the directory,
+from which FILE-NAME can be reached by descending directories
+along each part of MODULE.
+
+If the MODULE name does not match the directory hierarchy upwards
+from FILE-NAME, return the directory containing FILE-NAME.  When
+FILE-NAME is nil, return `default-directory'."
+  (let ((file-name (or file-name (buffer-file-name)))
+        (module-components (if (stringp module)
+                               (split-string module (rx "."))
+                             (copy-sequence module))))
+    (if (and module-components file-name)
+        (let ((parts (nreverse module-components))
+              (base-directory (directory-file-name
+                               (file-name-sans-extension file-name))))
+          (while (and parts
+                      (string= (file-name-nondirectory base-directory)
+                               (car parts)))
+            (pop parts)
+            (setq base-directory (directory-file-name
+                                  (file-name-directory base-directory))))
+          (file-name-as-directory base-directory))
+      (if file-name
+          (file-name-directory file-name)
+        (expand-file-name default-directory)))))
+
+
+;;; Minibuffer tools
+(defvar read-flycheck-checker-history nil
+  "`completing-read' history of `read-flycheck-checker'.")
+
+(defun flycheck-completing-read (prompt candidates default &optional history)
+  "Read a value from the minibuffer.
+
+Use `flycheck-completing-read-function' to read input from the
+minibuffer with completion.
+
+Show PROMPT and read one of CANDIDATES, defaulting to DEFAULT.
+HISTORY is passed to `flycheck-completing-read-function'."
+  (funcall flycheck-completing-read-function
+           prompt candidates nil 'require-match nil history default))
+
+(defun read-flycheck-checker (prompt &optional default property candidates)
+  "Read a flycheck checker from minibuffer with PROMPT and DEFAULT.
+
+PROMPT is a string to show in the minibuffer as prompt.  It
+should end with a single space.  DEFAULT is a symbol denoting the
+default checker to use, if the user did not select any checker.
+PROPERTY is a symbol denoting a syntax checker property.  If
+non-nil, only complete syntax checkers which have a non-nil value
+for PROPERTY.  CANDIDATES is an optional list of all syntax
+checkers available for completion, defaulting to all defined
+checkers.  If given, PROPERTY is ignored.
+
+Return the checker as symbol, or DEFAULT if no checker was
+chosen.  If DEFAULT is nil and no checker was chosen, signal a
+`user-error' if the underlying completion system does not provide
+a default on its own."
+  (when (and default (not (flycheck-valid-checker-p default)))
+    (error "%S is no valid Flycheck checker" default))
+  (let* ((candidates (seq-map #'symbol-name
+                              (or candidates
+                                  (flycheck-defined-checkers property))))
+         (default (and default (symbol-name default)))
+         (input (flycheck-completing-read
+                 prompt candidates default
+                 'read-flycheck-checker-history)))
+    (when (string-empty-p input)
+      (unless default
+        (user-error "No syntax checker selected"))
+      (setq input default))
+    (let ((checker (intern input)))
+      (unless (flycheck-valid-checker-p checker)
+        (error "%S is not a valid Flycheck syntax checker" checker))
+      checker)))
+
+(defun read-flycheck-error-level (prompt)
+  "Read an error level from the user with PROMPT.
+
+Only offers level for which errors currently exist, in addition
+to the default levels."
+  (let* ((levels (seq-map #'flycheck-error-level
+                          (flycheck-error-list-current-errors)))
+         (levels-with-defaults (append '(info warning error) levels))
+         (uniq-levels (seq-uniq levels-with-defaults))
+         (level (flycheck-completing-read prompt uniq-levels nil)))
+    (and (stringp level) (intern level))))
+
+
+;;; Checker API
+(defun flycheck-defined-checkers (&optional property)
+  "Find all defined syntax checkers, optionally with PROPERTY.
+
+PROPERTY is a symbol.  If given, only return syntax checkers with
+a non-nil value for PROPERTY.
+
+The returned list is sorted alphapetically by the symbol name of
+the syntax checkers."
+  (let (defined-checkers)
+    (mapatoms (lambda (symbol)
+                (when (and (flycheck-valid-checker-p symbol)
+                           (or (null property)
+                               (flycheck-checker-get symbol property)))
+                  (push symbol defined-checkers))))
+    (sort defined-checkers #'string<)))
+
+(defun flycheck-registered-checker-p (checker)
+  "Determine whether CHECKER is registered.
+
+A checker is registered if it is contained in
+`flycheck-checkers'."
+  (and (flycheck-valid-checker-p checker)
+       (memq checker flycheck-checkers)))
+
+(defun flycheck-disabled-checker-p (checker)
+  "Determine whether CHECKER is disabled.
+
+A checker is disabled if it is contained in
+`flycheck-disabled-checkers'."
+  (memq checker flycheck-disabled-checkers))
+
+
+;;; Generic syntax checkers
+(defconst flycheck-generic-checker-version 2
+  "The internal version of generic syntax checker declarations.
+
+Flycheck will not use syntax checkers whose generic version is
+less than this constant.")
+
+(defsubst flycheck--checker-property-name (property)
+  "Return the SYMBOL property for checker PROPERTY."
+  (intern (concat "flycheck-" (symbol-name property))))
+
+(defun flycheck-checker-get (checker property)
+  "Get the value of CHECKER's PROPERTY."
+  (get checker (flycheck--checker-property-name property)))
+
+(gv-define-setter flycheck-checker-get (value checker property)
+  `(setf (get ,checker (flycheck--checker-property-name ,property)) ,value))
+
+(defun flycheck-validate-next-checker (next &optional strict)
+  "Validate NEXT checker.
+
+With STRICT non-nil, also check whether the syntax checker and
+the error level in NEXT are valid.  Otherwise just check whether
+these are symbols.
+
+Signal an error if NEXT is not a valid entry for
+`:next-checkers'."
+  (when (symbolp next)
+    (setq next (cons t next)))
+  (pcase next
+    (`(,level . ,checker)
+     (if strict
+         (progn
+           (unless (or (eq level t) (flycheck-error-level-p level))
+             (error "%S is not a valid Flycheck error level" level))
+           (unless (flycheck-valid-checker-p checker)
+             (error "%s is not a valid Flycheck syntax checker" checker)))
+       (unless (symbolp level)
+         (error "Error level %S must be a symbol" level))
+       (unless (symbolp checker)
+         (error "Checker %S must be a symbol" checker))))
+    (_ (error "%S must be a symbol or cons cell" next)))
+  t)
+
+(defun flycheck-define-generic-checker (symbol docstring &rest properties)
+  "Define SYMBOL as generic syntax checker.
+
+Any syntax checker defined with this macro is eligible for manual
+syntax checker selection with `flycheck-select-checker'.  To make
+the new syntax checker available for automatic selection, it must
+be registered in `flycheck-checkers'.
+
+DOCSTRING is the documentation of the syntax checker, for
+`flycheck-describe-checker'.  The following PROPERTIES constitute
+a generic syntax checker.  Unless otherwise noted, all properties
+are mandatory.
+
+`:start FUNCTION'
+     A function to start the syntax checker.
+
+     FUNCTION shall take two arguments and return a context
+     object if the checker is started successfully.  Otherwise it
+     shall signal an error.
+
+     The first argument is the syntax checker being started.  The
+     second is a callback function to report state changes to
+     Flycheck.  The callback takes two arguments STATUS DATA,
+     where STATUS is a symbol denoting the syntax checker status
+     and DATA an optional argument with additional data for the
+     status report.  See `flycheck-report-buffer-checker-status'
+     for more information about STATUS and DATA.
+
+     FUNCTION may be synchronous or asynchronous, i.e. it may
+     call the given callback either immediately, or at some later
+     point (e.g. from a process sentinel).
+
+     A syntax checker _must_ call CALLBACK at least once with a
+     STATUS that finishes the current syntax checker.  Otherwise
+     Flycheck gets stuck at the current syntax check with this
+     syntax checker.
+
+     The context object returned by FUNCTION is passed to
+     `:interrupt'.
+
+`:interrupt FUNCTION'
+     A function to interrupt the syntax check.
+
+     FUNCTION is called with the syntax checker and the context
+     object returned by the `:start' function and shall try to
+     interrupt the syntax check.  The context may be nil, if the
+     syntax check is interrupted before actually started.
+     FUNCTION should handle this situation.
+
+     If it cannot interrupt the syntax check, it may either
+     signal an error or silently ignore the attempt to interrupt
+     the syntax checker, depending on the severity of the
+     situation.
+
+     If interrupting the syntax check failed, Flycheck will let
+     the syntax check continue, but ignore any status reports.
+     Notably, it won't highlight any errors reported by the
+     syntax check in the buffer.
+
+     This property is optional.  If omitted, Flycheck won't
+     attempt to interrupt syntax checks wit this syntax checker,
+     and simply ignore their results.
+
+`:print-doc FUNCTION'
+     A function to print additional documentation into the Help
+     buffer of this checker.
+
+     FUNCTION is called when creating the Help buffer for the
+     syntax checker, with the syntax checker as single argument,
+     after printing the name of the syntax checker and its modes
+     and predicate, but before printing DOCSTRING.  It may insert
+     additional documentation into the current buffer.
+
+     The call occurs within `with-help-window'.  Hence
+     `standard-output' points to the current buffer, so you may
+     use `princ' and friends to add content.  Also, the current
+     buffer is put into Help mode afterwards, which automatically
+     turns symbols into references, if possible.
+
+     This property is optional.  If omitted, no additional
+     documentation is printed for this syntax checker.
+
+:verify FUNCTION
+     A function to verify the checker for the current buffer.
+
+     FUNCTION is called with the syntax checker as single
+     argument, and shall return a list of
+     `flycheck-verification-result' objects indicating whether
+     the syntax checker could be used in the current buffer, and
+     highlighting potential setup problems.
+
+     This property is optional.  If omitted, no additional
+     verification occurs for this syntax checker.  It is however
+     absolutely recommended that you add a `:verify' function to
+     your syntax checker, because it will help users to spot
+     potential setup problems.
+
+`:modes MODES'
+     A major mode symbol or a list thereof, denoting major modes
+     to use this syntax checker in.
+
+     This syntax checker will only be used in buffers whose
+     `major-mode' is contained in MODES.
+
+     If `:predicate' is also given the syntax checker will only
+     be used in buffers for which the `:predicate' returns
+     non-nil.
+
+`:predicate FUNCTION'
+     A function to determine whether to use the syntax checker in
+     the current buffer.
+
+     FUNCTION is called without arguments and shall return
+     non-nil if this syntax checker shall be used to check the
+     current buffer.  Otherwise it shall return nil.
+
+     If this checker has a `:working-directory' FUNCTION is
+     called with `default-directory' bound to the checker's
+     working directory.
+
+     FUNCTION is only called in matching major modes.
+
+     This property is optional.
+
+`:enabled FUNCTION'
+     A function to determine whether to use the syntax checker in
+     the current buffer.
+
+     This property behaves as `:predicate', except that it's only
+     called the first time a syntax checker is to be used in a buffer.
+
+     FUNCTION is called without arguments and shall return
+     non-nil if this syntax checker shall be used to check the
+     current buffer.  Otherwise it shall return nil.
+
+     If FUNCTION returns a non-nil value the checker is put in a
+     whitelist in `flycheck-enabled-checkers' to prevent further
+     invocations of `:enabled'.  Otherwise it is disabled via
+     `flycheck-disabled-checkers' to prevent any further use of
+     it.
+
+     If this checker has a `:working-directory' FUNCTION is
+     called with `default-directory' bound to the checker's
+     working directory.
+
+     FUNCTION is only called in matching major modes.
+
+     This property is optional.
+
+`:error-filter FUNCTION'
+     A function to filter the errors returned by this checker.
+
+     FUNCTION is called with the list of `flycheck-error' objects
+     returned by the syntax checker and shall return another list
+     of `flycheck-error' objects, which is considered the final
+     result of this syntax checker.
+
+     FUNCTION is free to add, remove or modify errors, whether in
+     place or by copying.
+
+     This property is optional.  The default filter is
+     `identity'.
+
+`:error-explainer FUNCTION'
+     A function to return an explanation text for errors
+     generated by this checker.
+
+     FUNCTION is called with a `flycheck-error' object and shall
+     return an explanation message for this error as a string, or
+     nil if there is no explanation for this error.
+
+     This property is optional.
+
+`:next-checkers NEXT-CHECKERS'
+     A list denoting syntax checkers to apply after this syntax
+     checker, in what we call \"chaining\" of syntax checkers.
+
+     Each ITEM is a cons cell `(LEVEL . CHECKER)'.  CHECKER is a
+     syntax checker to run after this syntax checker.  LEVEL is
+     an error level.  CHECKER will only be used if there are no
+     current errors of at least LEVEL.  LEVEL may also be t, in
+     which case CHECKER is used regardless of the current errors.
+
+     ITEM may also be a syntax checker symbol, which is
+     equivalent to `(t . ITEM)'.
+
+     Flycheck tries all items in order of declaration, and uses
+     the first whose LEVEL matches and whose CHECKER is
+     registered and can be used for the current buffer.
+
+     This feature is typically used to apply more than one syntax
+     checker to a buffer.  For instance, you might first use a
+     compiler to check a buffer for syntax and type errors, and
+     then run a linting tool that checks for insecure code, or
+     questionable style.
+
+     This property is optional.  If omitted, it defaults to the
+     nil, i.e. no other syntax checkers are applied after this
+     syntax checker.
+
+`:working-directory FUNCTION'
+     The value of `default-directory' when invoking `:start'.
+
+     FUNCTION is a function taking the syntax checker as sole
+     argument.  It shall return the absolute path to an existing
+     directory to use as `default-directory' for `:start' or
+     nil to fall back to the `default-directory' of the current
+     buffer.
+
+     This property is optional.  If omitted, invoke `:start'
+     from the `default-directory' of the buffer being checked.
+
+Signal an error, if any property has an invalid value."
+  (declare (indent 1)
+           (doc-string 2))
+  (let ((start (plist-get properties :start))
+        (interrupt (plist-get properties :interrupt))
+        (print-doc (plist-get properties :print-doc))
+        (modes (plist-get properties :modes))
+        (predicate (plist-get properties :predicate))
+        (verify (plist-get properties :verify))
+        (enabled (plist-get properties :enabled))
+        (filter (or (plist-get properties :error-filter) #'identity))
+        (explainer (plist-get properties :error-explainer))
+        (next-checkers (plist-get properties :next-checkers))
+        (file (flycheck-current-load-file))
+        (working-directory (plist-get properties :working-directory)))
+
+    (unless (listp modes)
+      (setq modes (list modes)))
+
+    (unless (functionp start)
+      (error ":start %S of syntax checker %s is not a function" start symbol))
+    (unless (or (null interrupt) (functionp interrupt))
+      (error ":interrupt %S of syntax checker %s is not a function"
+             interrupt symbol))
+    (unless (or (null print-doc) (functionp print-doc))
+      (error ":print-doc %S of syntax checker %s is not a function"
+             print-doc symbol))
+    (unless (or (null verify) (functionp verify))
+      (error ":verify %S of syntax checker %S is not a function"
+             verify symbol))
+    (unless (or (null enabled) (functionp enabled))
+      (error ":enabled %S of syntax checker %S is not a function"
+             enabled symbol))
+    (unless modes
+      (error "Missing :modes in syntax checker %s" symbol))
+    (dolist (mode modes)
+      (unless (symbolp mode)
+        (error "Invalid :modes %s in syntax checker %s, %s must be a symbol"
+               modes symbol mode)))
+    (unless (or (null predicate) (functionp predicate))
+      (error ":predicate %S of syntax checker %s  is not a function"
+             predicate symbol))
+    (unless (functionp filter)
+      (error ":error-filter %S of syntax checker %s is not a function"
+             filter symbol))
+    (unless (or (null explainer) (functionp explainer))
+      (error ":error-explainer %S of syntax checker %S is not a function"
+             explainer symbol))
+    (dolist (checker next-checkers)
+      (flycheck-validate-next-checker checker))
+
+    (let ((real-predicate
+           (and predicate
+                (lambda ()
+                  ;; Run predicate in the checker's default directory
+                  (let ((default-directory
+                          (flycheck-compute-working-directory symbol)))
+                    (funcall predicate)))))
+          (real-enabled
+           (lambda ()
+             (if (flycheck-valid-checker-p symbol)
+                 (or (null enabled)
+                     ;; Run enabled in the checker's default directory
+                     (let ((default-directory
+                             (flycheck-compute-working-directory symbol)))
+                       (funcall enabled)))
+               (lwarn 'flycheck
+                      :warning "%S is no valid Flycheck syntax checker.
+Try to reinstall the package defining this syntax checker." symbol)
+               nil))))
+      (pcase-dolist (`(,prop . ,value)
+                     `((start             . ,start)
+                       (interrupt         . ,interrupt)
+                       (print-doc         . ,print-doc)
+                       (modes             . ,modes)
+                       (predicate         . ,real-predicate)
+                       (verify            . ,verify)
+                       (enabled           . ,real-enabled)
+                       (error-filter      . ,filter)
+                       (error-explainer   . ,explainer)
+                       (next-checkers     . ,next-checkers)
+                       (documentation     . ,docstring)
+                       (file              . ,file)
+                       (working-directory . ,working-directory)))
+        (setf (flycheck-checker-get symbol prop) value)))
+
+    ;; Track the version, to avoid breakage if the internal format changes
+    (setf (flycheck-checker-get symbol 'generic-checker-version)
+          flycheck-generic-checker-version)))
+
+(defun flycheck-valid-checker-p (checker)
+  "Check whether a CHECKER is valid.
+
+A valid checker is a symbol defined as syntax checker with
+`flycheck-define-checker'."
+  (and (symbolp checker)
+       (= (or (get checker 'flycheck-generic-checker-version) 0)
+          flycheck-generic-checker-version)))
+
+(defun flycheck-checker-supports-major-mode-p (checker &optional mode)
+  "Whether CHECKER supports the given major MODE.
+
+CHECKER is a syntax checker symbol and MODE a major mode symbol.
+Look at the `modes' property of CHECKER to determine whether
+CHECKER supports buffers in the given major MODE.
+
+MODE defaults to the value of `major-mode' if omitted or nil.
+
+Return non-nil if CHECKER supports MODE and nil otherwise."
+  (let ((mode (or mode major-mode)))
+    (memq mode (flycheck-checker-get checker 'modes))))
+
+(defvar-local flycheck-enabled-checkers nil
+  "Syntax checkers included in automatic selection.
+
+A list of Flycheck syntax checkers included in automatic
+selection for current buffer.")
+
+(defun flycheck-may-enable-checker (checker)
+  "Whether a generic CHECKER may be enabled for current buffer.
+
+Return non-nil if CHECKER may be used for the current buffer, and
+nil otherwise."
+  (let* ((enabled (flycheck-checker-get checker 'enabled))
+         (shall-enable (and (not (flycheck-disabled-checker-p checker))
+                            (or (memq checker flycheck-enabled-checkers)
+                                (null enabled)
+                                (funcall enabled)))))
+    (if shall-enable
+        (cl-pushnew checker flycheck-enabled-checkers)
+      (cl-pushnew checker flycheck-disabled-checkers))
+    shall-enable))
+
+(defun flycheck-may-use-checker (checker)
+  "Whether a generic CHECKER may be used.
+
+Return non-nil if CHECKER may be used for the current buffer, and
+nil otherwise."
+  (let ((predicate (flycheck-checker-get checker 'predicate)))
+    (and (flycheck-valid-checker-p checker)
+         (flycheck-checker-supports-major-mode-p checker)
+         (flycheck-may-enable-checker checker)
+         (or (null predicate) (funcall predicate)))))
+
+(defun flycheck-may-use-next-checker (next-checker)
+  "Determine whether NEXT-CHECKER may be used."
+  (when (symbolp next-checker)
+    (push t next-checker))
+  (let ((level (car next-checker))
+        (next-checker (cdr next-checker)))
+    (and (or (eq level t)
+             (flycheck-has-max-current-errors-p level))
+         (flycheck-registered-checker-p next-checker)
+         (flycheck-may-use-checker next-checker))))
+
+
+;;; Help for generic syntax checkers
+(define-button-type 'help-flycheck-checker-def
+  :supertype 'help-xref
+  'help-function #'flycheck-goto-checker-definition
+  'help-echo "mouse-2, RET: find Flycheck checker definition")
+
+(defconst flycheck-find-checker-regexp
+  (rx line-start (zero-or-more (syntax whitespace))
+      "(" symbol-start "flycheck-define-checker" symbol-end
+      (eval (list 'regexp find-function-space-re))
+      symbol-start
+      "%s"
+      symbol-end
+      (or (syntax whitespace) line-end))
+  "Regular expression to find a checker definition.")
+
+(add-to-list 'find-function-regexp-alist
+             '(flycheck-checker . flycheck-find-checker-regexp))
+
+(defun flycheck-goto-checker-definition (checker file)
+  "Go to to the definition of CHECKER in FILE."
+  (let ((location (find-function-search-for-symbol
+                   checker 'flycheck-checker file)))
+    (pop-to-buffer (car location))
+    (if (cdr location)
+        (goto-char (cdr location))
+      (message "Unable to find checker location in file"))))
+
+(defun flycheck-checker-at-point ()
+  "Return the Flycheck checker found at or before point.
+
+Return nil if there is no checker."
+  (let ((symbol (variable-at-point 'any-symbol)))
+    (when (flycheck-valid-checker-p symbol)
+      symbol)))
+
+(defun flycheck-describe-checker (checker)
+  "Display the documentation of CHECKER.
+
+CHECKER is a checker symbol.
+
+Pop up a help buffer with the documentation of CHECKER."
+  (interactive
+   (let* ((enable-recursive-minibuffers t)
+          (default (or (flycheck-checker-at-point)
+                       (ignore-errors (flycheck-get-checker-for-buffer))))
+          (prompt (if default
+                      (format "Describe syntax checker (default %s): " default)
+                    "Describe syntax checker: ")))
+     (list (read-flycheck-checker prompt default))))
+  (unless (flycheck-valid-checker-p checker)
+    (user-error "You didn't specify a Flycheck syntax checker"))
+  (help-setup-xref (list #'flycheck-describe-checker checker)
+                   (called-interactively-p 'interactive))
+  (save-excursion
+    (with-help-window (help-buffer)
+      (let ((filename (flycheck-checker-get checker 'file))
+            (modes (flycheck-checker-get checker 'modes))
+            (predicate (flycheck-checker-get checker 'predicate))
+            (print-doc (flycheck-checker-get checker 'print-doc))
+            (next-checkers (flycheck-checker-get checker 'next-checkers)))
+        (princ (format "%s is a Flycheck syntax checker" checker))
+        (when filename
+          (princ (format " in `%s'" (file-name-nondirectory filename)))
+          (with-current-buffer standard-output
+            (save-excursion
+              (re-search-backward "`\\([^`']+\\)'" nil t)
+              (help-xref-button 1 'help-flycheck-checker-def
+                                checker filename))))
+        (princ ".\n\n")
+
+        (let ((modes-start (with-current-buffer standard-output (point-max))))
+          ;; Track the start of the modes documentation, to properly re-fill
+          ;; it later
+          (princ "  This syntax checker checks syntax in the major mode(s) ")
+          (princ (string-join
+                  (seq-map (apply-partially #'format "`%s'") modes)
+                  ", "))
+          (when predicate
+            (princ ", and uses a custom predicate"))
+          (princ ".")
+          (when next-checkers
+            (princ "  It runs the following checkers afterwards:"))
+          (with-current-buffer standard-output
+            (save-excursion
+              (fill-region-as-paragraph modes-start (point-max))))
+          (princ "\n")
+
+          ;; Print the list of next checkers
+          (when next-checkers
+            (princ "\n")
+            (let ((beg-checker-list (with-current-buffer standard-output
+                                      (point))))
+              (dolist (next-checker next-checkers)
+                (if (symbolp next-checker)
+                    (princ (format "     * `%s'\n" next-checker))
+                  (princ (format "     * `%s' (maximum level `%s')\n"
+                                 (cdr next-checker) (car next-checker)))))
+              ;;
+              (with-current-buffer standard-output
+                (save-excursion
+                  (while (re-search-backward "`\\([^`']+\\)'"
+                                             beg-checker-list t)
+                    (when (flycheck-valid-checker-p
+                           (intern-soft (match-string 1)))
+                      (help-xref-button 1 'help-flycheck-checker-def checker
+                                        filename))))))))
+        ;; Call the custom print-doc function of the checker, if present
+        (when print-doc
+          (funcall print-doc checker))
+        ;; Ultimately, print the docstring
+        (princ "\nDocumentation:\n")
+        (princ (flycheck-checker-get checker 'documentation))))))
+
+
+;;; Syntax checker verification
+(cl-defstruct (flycheck-verification-result
+               (:constructor flycheck-verification-result-new))
+  "Structure for storing a single verification result.
+
+Slots:
+
+`label'
+     A label for this result, as string
+
+`message'
+     A message for this result, as string
+
+`face'
+     The face to use for the `message'.
+
+     You can either use a face symbol, or a list of face symbols."
+  label message face)
+
+(defun flycheck-verify-generic-checker (checker)
+  "Verify a generic CHECKER in the current buffer.
+
+Return a list of `flycheck-verification-result' objects."
+  (let (results
+        (predicate (flycheck-checker-get checker 'predicate))
+        (enabled (flycheck-checker-get checker 'enabled))
+        (verify (flycheck-checker-get checker 'verify)))
+    (when enabled
+      (let ((result (funcall enabled)))
+        (push (flycheck-verification-result-new
+               :label "may enable"
+               :message (if result "yes" "Automatically disabled!")
+               :face (if result 'success '(bold warning)))
+              results)))
+    (when predicate
+      (let ((result (funcall predicate)))
+        (push (flycheck-verification-result-new
+               :label "predicate"
+               :message (prin1-to-string (not (null result)))
+               :face (if result 'success '(bold warning)))
+              results)))
+    (append (nreverse results)
+            (and verify (funcall verify checker)))))
+
+(define-button-type 'help-flycheck-checker-doc
+  :supertype 'help-xref
+  'help-function #'flycheck-describe-checker
+  'help-echo "mouse-2, RET: describe Flycheck checker")
+
+(defun flycheck--verify-princ-checker (checker buffer &optional with-mm)
+  "Print verification result of CHECKER for BUFFER.
+
+When WITH-MM is given and non-nil, also include the major mode
+into the verification results."
+  (princ "  ")
+  (insert-button (symbol-name checker)
+                 'type 'help-flycheck-checker-doc
+                 'help-args (list checker))
+  (when (with-current-buffer buffer (flycheck-disabled-checker-p checker))
+    (insert (propertize " (disabled)" 'face '(bold error))))
+  (princ "\n")
+  (let ((results (with-current-buffer buffer
+                   (flycheck-verify-generic-checker checker))))
+    (when with-mm
+      (with-current-buffer buffer
+        (let ((message-and-face
+               (if (flycheck-checker-supports-major-mode-p checker)
+                   (cons (format "`%s' supported" major-mode) 'success)
+                 (cons (format "`%s' not supported" major-mode) 'error))))
+          (push (flycheck-verification-result-new
+                 :label "major mode"
+                 :message (car message-and-face)
+                 :face (cdr message-and-face))
+                results))))
+    (let* ((label-length
+            (seq-max (mapcar
+                      (lambda (res)
+                        (length (flycheck-verification-result-label res)))
+                      results)))
+           (message-column (+ 8 label-length)))
+      (dolist (result results)
+        (princ "    - ")
+        (princ (flycheck-verification-result-label result))
+        (princ ": ")
+        (princ (make-string (- message-column (current-column)) ?\ ))
+        (let ((message (flycheck-verification-result-message result))
+              (face (flycheck-verification-result-face result)))
+          (insert (propertize message 'face face)))
+        (princ "\n"))))
+  (princ "\n"))
+
+(defun flycheck--verify-print-header (desc buffer)
+  "Print a title with DESC for BUFFER in the current buffer.
+
+DESC is an arbitrary string containing a description, and BUFFER
+is the buffer being verified.  The name and the major mode mode
+of BUFFER are printed.
+
+DESC and information about BUFFER are printed in the current
+buffer."
+  (princ desc)
+  (insert (propertize (buffer-name buffer) 'face 'bold))
+  (princ " in ")
+  (let ((mode (buffer-local-value 'major-mode buffer)))
+    (insert-button (symbol-name mode)
+                   'type 'help-function
+                   'help-args (list mode)))
+  (princ ":\n\n"))
+
+(defun flycheck--verify-print-footer (buffer)
+  "Print a footer for BUFFER in the current buffer.
+
+BUFFER is the buffer being verified."
+  (princ "Flycheck Mode is ")
+  (let ((enabled (buffer-local-value 'flycheck-mode buffer)))
+    (insert (propertize (if enabled "enabled" "disabled")
+                        'face (if enabled 'success '(warning bold)))))
+  (princ
+   (with-current-buffer buffer
+     ;; Use key binding state in the verified buffer to print the help.
+     (substitute-command-keys
+      ".  Use \\[universal-argument] \\[flycheck-disable-checker] \
+to enable disabled checkers.")))
+  (save-excursion
+    (let ((end (point)))
+      (backward-paragraph)
+      (fill-region-as-paragraph (point) end)))
+
+  (princ "\n\n--------------------\n\n")
+  (princ (format "Flycheck version: %s\n" (flycheck-version)))
+  (princ (format "Emacs version:    %s\n" emacs-version))
+  (princ (format "System:           %s\n" system-configuration))
+  (princ (format "Window system:    %S\n" window-system)))
+
+(defun flycheck-verify-checker (checker)
+  "Check whether a CHECKER can be used in this buffer.
+
+Show a buffer listing possible problems that prevent CHECKER from
+being used for the current buffer.
+
+Note: Do not use this function to check whether a syntax checker
+is applicable from Emacs Lisp code.  Use
+`flycheck-may-use-checker' instead."
+  (interactive (list (read-flycheck-checker "Checker to verify: ")))
+  (unless (flycheck-valid-checker-p checker)
+    (user-error "%s is not a syntax checker" checker))
+
+  ;; Save the buffer to make sure that all predicates are good
+  (when (and (buffer-file-name) (buffer-modified-p))
+    (save-buffer))
+
+  (let ((buffer (current-buffer)))
+    (with-help-window (get-buffer-create " *Flycheck checker*")
+      (with-current-buffer standard-output
+        (flycheck--verify-print-header "Syntax checker in buffer " buffer)
+        (flycheck--verify-princ-checker checker buffer 'with-mm)
+        (if (with-current-buffer buffer (flycheck-may-use-checker checker))
+            (insert (propertize
+                     "Flycheck can use this syntax checker for this buffer.\n"
+                     'face 'success))
+          (insert (propertize
+                   "Flycheck cannot use this syntax checker for this buffer.\n"
+                   'face 'error)))
+        (insert "\n")
+        (flycheck--verify-print-footer buffer)))))
+
+(defun flycheck-verify-setup ()
+  "Check whether Flycheck can be used in this buffer.
+
+Display a new buffer listing all syntax checkers that could be
+applicable in the current buffer.  For each syntax checkers,
+possible problems are shown."
+  (interactive)
+  (when (and (buffer-file-name) (buffer-modified-p))
+    ;; Save the buffer
+    (save-buffer))
+
+  (let ((buffer (current-buffer))
+        ;; Get all checkers that support the current major mode
+        (checkers (seq-filter #'flycheck-checker-supports-major-mode-p
+                              flycheck-checkers))
+        (help-buffer (get-buffer-create " *Flycheck checkers*")))
+
+    ;; Now print all applicable checkers
+    (with-help-window help-buffer
+      (with-current-buffer standard-output
+        (flycheck--verify-print-header "Syntax checkers for buffer " buffer)
+        (unless checkers
+          (insert (propertize
+                   "There are no syntax checkers for this buffer!\n\n"
+                   'face '(bold error))))
+        (dolist (checker checkers)
+          (flycheck--verify-princ-checker checker buffer))
+
+        (-when-let (selected-checker
+                    (buffer-local-value 'flycheck-checker buffer))
+          (insert
+           (propertize
+            "The following checker is explicitly selected for this buffer:\n\n"
+            'face 'bold))
+          (flycheck--verify-princ-checker selected-checker buffer 'with-mm))
+
+        (let ((unregistered-checkers
+               (seq-difference (flycheck-defined-checkers) flycheck-checkers)))
+          (when unregistered-checkers
+            (insert (propertize
+                     "\nThe following syntax checkers are not registered:\n\n"
+                     'face '(bold warning)))
+            (dolist (checker unregistered-checkers)
+              (princ "  - ")
+              (princ checker)
+              (princ "\n"))
+            (princ
+             "\nTry adding these syntax checkers to `flycheck-checkers'.\n")))
+
+        (flycheck--verify-print-footer buffer)))
+
+    (with-current-buffer help-buffer
+      (setq-local revert-buffer-function
+                  (lambda (_ignore-auto _noconfirm)
+                    (with-current-buffer buffer (flycheck-verify-setup)))))))
+
+
+;;; Predicates for generic syntax checkers
+(defun flycheck-buffer-saved-p (&optional buffer)
+  "Determine whether BUFFER is saved to a file.
+
+BUFFER is the buffer to check.  If omitted or nil, use the
+current buffer as BUFFER.
+
+Return non-nil if the BUFFER is backed by a file, and not
+modified, or nil otherwise."
+  (let ((file-name (buffer-file-name buffer)))
+    (and file-name (file-exists-p file-name) (not (buffer-modified-p buffer)))))
+
+
+;;; Extending generic checkers
+(defun flycheck-add-next-checker (checker next &optional append)
+  "After CHECKER add a NEXT checker.
+
+CHECKER is a syntax checker symbol, to which to add NEXT checker.
+
+NEXT is a cons cell `(LEVEL . NEXT-CHECKER)'.  NEXT-CHECKER is a
+symbol denoting the syntax checker to run after CHECKER.  LEVEL
+is an error level.  NEXT-CHECKER will only be used if there is no
+current error whose level is more severe than LEVEL.  LEVEL may
+also be t, in which case NEXT-CHECKER is used regardless of the
+current errors.
+
+NEXT can also be a syntax checker symbol only, which is
+equivalent to `(t . NEXT)'.
+
+NEXT-CHECKER is prepended before other next checkers, unless
+APPEND is non-nil."
+  (unless (flycheck-valid-checker-p checker)
+    (error "%s is not a valid syntax checker" checker))
+  (flycheck-validate-next-checker next 'strict)
+  (if append
+      (setf (flycheck-checker-get checker 'next-checkers)
+            (append (flycheck-checker-get checker 'next-checkers) (list next)))
+    (push next (flycheck-checker-get checker 'next-checkers))))
+
+(defun flycheck-add-mode (checker mode)
+  "To CHECKER add a new major MODE.
+
+CHECKER and MODE are symbols denoting a syntax checker and a
+major mode respectively.
+
+Add MODE to the `:modes' property of CHECKER, so that CHECKER
+will be used in buffers with MODE."
+  (unless (flycheck-valid-checker-p checker)
+    (error "%s is not a valid syntax checker" checker))
+  (unless (symbolp mode)
+    (error "%s is not a symbol" mode))
+  (push mode (flycheck-checker-get checker 'modes)))
+
+
+;;; Generic syntax checks
+(cl-defstruct (flycheck-syntax-check
+               (:constructor flycheck-syntax-check-new))
+  "Structure for storing syntax check state.
+
+Slots:
+
+`buffer'
+     The buffer being checked.
+
+`checker'
+     The syntax checker being used.
+
+`context'
+     The context object.
+
+`working-directory'
+     Working directory for the syntax checker. Serve as a value for
+     `default-directory' for a checker."
+  buffer checker context working-directory)
+
+(defun flycheck-syntax-check-start (syntax-check callback)
+  "Start a SYNTAX-CHECK with CALLBACK."
+  (let ((checker (flycheck-syntax-check-checker syntax-check))
+        (default-directory
+          (flycheck-syntax-check-working-directory syntax-check)))
+    (setf (flycheck-syntax-check-context syntax-check)
+          (funcall (flycheck-checker-get checker 'start) checker callback))))
+
+(defun flycheck-syntax-check-interrupt (syntax-check)
+  "Interrupt a SYNTAX-CHECK."
+  (let* ((checker (flycheck-syntax-check-checker syntax-check))
+         (interrupt-fn (flycheck-checker-get checker 'interrupt))
+         (context (flycheck-syntax-check-context syntax-check)))
+    (when interrupt-fn
+      (funcall interrupt-fn checker context))))
+
+
+;;; Syntax checking mode
+
+(defvar flycheck-mode-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map flycheck-keymap-prefix flycheck-command-map)
+    ;; We place the menu under a custom menu key.  Since this menu key is not
+    ;; present in the menu of the global map, no top-level menu entry is added
+    ;; to the global menu bar.  However, it still appears on the mode line
+    ;; lighter.
+    (define-key map [menu-bar flycheck] flycheck-mode-menu-map)
+    map)
+  "Keymap of command `flycheck-mode'.")
+
+(defvar-local flycheck-old-next-error-function nil
+  "Remember the old `next-error-function'.")
+
+(defconst flycheck-hooks-alist
+  '(
+    ;; Handle events that may start automatic syntax checks
+    (after-save-hook        . flycheck-handle-save)
+    (after-change-functions . flycheck-handle-change)
+    ;; Handle events that may triggered pending deferred checks
+    (window-configuration-change-hook . flycheck-perform-deferred-syntax-check)
+    (post-command-hook                . flycheck-perform-deferred-syntax-check)
+    ;; Teardown Flycheck whenever the buffer state is about to get lost, to
+    ;; clean up temporary files and directories.
+    (kill-buffer-hook       . flycheck-teardown)
+    (change-major-mode-hook . flycheck-teardown)
+    (before-revert-hook     . flycheck-teardown)
+    ;; Update the error list if necessary
+    (post-command-hook . flycheck-error-list-update-source)
+    (post-command-hook . flycheck-error-list-highlight-errors)
+    ;; Display errors.  Show errors at point after commands (like movements) and
+    ;; when Emacs gets focus.  Cancel the display timer when Emacs looses focus
+    ;; (as there's no need to display errors if the user can't see them), and
+    ;; hide the error buffer (for large error messages) if necessary.  Note that
+    ;; the focus hooks only work on Emacs 24.4 and upwards, but since undefined
+    ;; hooks are perfectly ok we don't need a version guard here.  They'll just
+    ;; not work silently.
+    (post-command-hook . flycheck-display-error-at-point-soon)
+    (focus-in-hook     . flycheck-display-error-at-point-soon)
+    (focus-out-hook    . flycheck-cancel-error-display-error-at-point-timer)
+    (post-command-hook . flycheck-hide-error-buffer)
+    ;; Immediately show error popups when navigating to an error
+    (next-error-hook . flycheck-display-error-at-point))
+  "Hooks which Flycheck needs to hook in.
+
+The `car' of each pair is a hook variable, the `cdr' a function
+to be added or removed from the hook variable if Flycheck mode is
+enabled and disabled respectively.")
+
+;;;###autoload
+(define-minor-mode flycheck-mode
+  "Minor mode for on-the-fly syntax checking.
+
+When called interactively, toggle `flycheck-mode'.  With prefix
+ARG, enable `flycheck-mode' if ARG is positive, otherwise disable
+it.
+
+When called from Lisp, enable `flycheck-mode' if ARG is omitted,
+nil or positive.  If ARG is `toggle', toggle `flycheck-mode'.
+Otherwise behave as if called interactively.
+
+In `flycheck-mode' the buffer is automatically syntax-checked
+using the first suitable syntax checker from `flycheck-checkers'.
+Use `flycheck-select-checker' to select a checker for the current
+buffer manually.
+
+\\{flycheck-mode-map}"
+  :init-value nil
+  :keymap flycheck-mode-map
+  :lighter flycheck-mode-line
+  :after-hook (flycheck-buffer-automatically 'mode-enabled 'force-deferred)
+  (cond
+   (flycheck-mode
+    (flycheck-clear)
+
+    (pcase-dolist (`(,hook . ,fn) flycheck-hooks-alist)
+      (add-hook hook fn nil 'local))
+
+    (setq flycheck-old-next-error-function
+          (if flycheck-standard-error-navigation
+              next-error-function
+            :unset))
+    (when flycheck-standard-error-navigation
+      (setq next-error-function #'flycheck-next-error-function)))
+   (t
+    (unless (eq flycheck-old-next-error-function :unset)
+      (setq next-error-function flycheck-old-next-error-function))
+
+    (pcase-dolist (`(,hook . ,fn) flycheck-hooks-alist)
+      (remove-hook hook fn 'local))
+
+    (flycheck-teardown))))
+
+
+;;; Syntax checker selection for the current buffer
+(defun flycheck-get-checker-for-buffer ()
+  "Find the checker for the current buffer.
+
+Use the selected checker for the current buffer, if any,
+otherwise search for the best checker from `flycheck-checkers'.
+
+Return checker if there is a checker for the current buffer, or
+nil otherwise."
+  (if flycheck-checker
+      (when (flycheck-may-use-checker flycheck-checker)
+        flycheck-checker)
+    (seq-find #'flycheck-may-use-checker flycheck-checkers)))
+
+(defun flycheck-get-next-checker-for-buffer (checker)
+  "Get the checker to run after CHECKER for the current buffer."
+  (let ((next (seq-find #'flycheck-may-use-next-checker
+                        (flycheck-checker-get checker 'next-checkers))))
+    (when next
+      (if (symbolp next) next (cdr next)))))
+
+(defun flycheck-select-checker (checker)
+  "Select CHECKER for the current buffer.
+
+CHECKER is a syntax checker symbol (see `flycheck-checkers') or
+nil.  In the former case, use CHECKER for the current buffer,
+otherwise deselect the current syntax checker (if any) and use
+automatic checker selection via `flycheck-checkers'.
+
+If called interactively prompt for CHECKER.  With prefix arg
+deselect the current syntax checker and enable automatic
+selection again.
+
+Set `flycheck-checker' to CHECKER and automatically start a new
+syntax check if the syntax checker changed.
+
+CHECKER will be used, even if it is not contained in
+`flycheck-checkers', or if it is disabled via
+`flycheck-disabled-checkers'."
+  (interactive
+   (if current-prefix-arg
+       (list nil)
+     (list (read-flycheck-checker "Select checker: "
+                                  (flycheck-get-checker-for-buffer)))))
+  (when (not (eq checker flycheck-checker))
+    (unless (or (not checker) (flycheck-may-use-checker checker))
+      (flycheck-verify-checker checker)
+      (user-error "Can't use syntax checker %S in this buffer" checker))
+    (setq flycheck-checker checker)
+    (when flycheck-mode
+      (flycheck-buffer))))
+
+(defun flycheck-disable-checker (checker &optional enable)
+  "Interactively disable CHECKER for the current buffer.
+
+Interactively, prompt for a syntax checker to disable, and add
+the syntax checker to the buffer-local value of
+`flycheck-disabled-checkers'.
+
+With non-nil ENABLE or with prefix arg, prompt for a disabled
+syntax checker and re-enable it by removing it from the
+buffer-local value of `flycheck-disabled-checkers'."
+  (declare
+   (interactive-only "Directly set `flycheck-disabled-checkers' instead"))
+  (interactive
+   (let* ((enable current-prefix-arg)
+          (candidates (if enable flycheck-disabled-checkers flycheck-checkers))
+          (prompt (if enable "Enable syntax checker: "
+                    "Disable syntax checker: ")))
+     (when (and enable (not candidates))
+       (user-error "No syntax checkers disabled in this buffer"))
+     (list (read-flycheck-checker prompt nil nil candidates) enable)))
+  (unless checker
+    (user-error "No syntax checker given"))
+  (if enable
+      ;; We must use `remq' instead of `delq', because we must _not_ modify the
+      ;; list.  Otherwise we could potentially modify the global default value,
+      ;; in case the list is the global default.
+      (when (memq checker flycheck-disabled-checkers)
+        (setq flycheck-disabled-checkers
+              (remq checker flycheck-disabled-checkers))
+        (flycheck-buffer))
+    (unless (memq checker flycheck-disabled-checkers)
+      (push checker flycheck-disabled-checkers)
+      (flycheck-buffer))))
+
+
+;;; Syntax checks for the current buffer
+(defvar-local flycheck-current-syntax-check nil
+  "The current syntax check in the this buffer.")
+(put 'flycheck-current-syntax-check 'permanent-local t)
+
+(defun flycheck-start-current-syntax-check (checker)
+  "Start a syntax check in the current buffer with CHECKER.
+
+Set `flycheck-current-syntax-check' accordingly."
+  ;; Allocate the current syntax check *before* starting it.  This allows for
+  ;; synchronous checks, which call the status callback immediately in their
+  ;; start function.
+  (let* ((check
+          (flycheck-syntax-check-new
+           :buffer (current-buffer)
+           :checker checker
+           :context nil
+           :working-directory (flycheck-compute-working-directory checker)))
+         (callback (flycheck-buffer-status-callback check)))
+    (setq flycheck-current-syntax-check check)
+    (flycheck-report-status 'running)
+    (flycheck-syntax-check-start check callback)))
+
+(defun flycheck-running-p ()
+  "Determine whether a syntax check is running in the current buffer."
+  (not (null flycheck-current-syntax-check)))
+
+(defun flycheck-stop ()
+  "Stop any ongoing syntax check in the current buffer."
+  (when (flycheck-running-p)
+    (flycheck-syntax-check-interrupt flycheck-current-syntax-check)
+    ;; Remove the current syntax check, to reset Flycheck into a non-running
+    ;; state, and to make `flycheck-report-buffer-checker-status' ignore any
+    ;; status reports from the current syntax check.
+    (setq flycheck-current-syntax-check nil)
+    (flycheck-report-status 'interrupted)))
+
+(defun flycheck-buffer-status-callback (syntax-check)
+  "Create a status callback for SYNTAX-CHECK in the current buffer."
+  (lambda (&rest args)
+    (apply #'flycheck-report-buffer-checker-status
+           syntax-check args)))
+
+(defun flycheck-buffer ()
+  "Start checking syntax in the current buffer.
+
+Get a syntax checker for the current buffer with
+`flycheck-get-checker-for-buffer', and start it."
+  (interactive)
+  (flycheck-clean-deferred-check)
+  (if flycheck-mode
+      (unless (flycheck-running-p)
+        ;; Clear error list and mark all overlays for deletion.  We do not
+        ;; delete all overlays immediately to avoid excessive re-displays and
+        ;; flickering, if the same errors gets highlighted again after the check
+        ;; completed.
+        (run-hooks 'flycheck-before-syntax-check-hook)
+        (flycheck-clear-errors)
+        (flycheck-mark-all-overlays-for-deletion)
+        (condition-case err
+            (let* ((checker (flycheck-get-checker-for-buffer)))
+              (if checker
+                  (flycheck-start-current-syntax-check checker)
+                (flycheck-clear)
+                (flycheck-report-status 'no-checker)))
+          (error
+           (flycheck-report-failed-syntax-check)
+           (signal (car err) (cdr err)))))
+    (user-error "Flycheck mode disabled")))
+
+(defun flycheck-report-buffer-checker-status
+    (syntax-check status &optional data)
+  "In BUFFER, report a SYNTAX-CHECK STATUS with DATA.
+
+SYNTAX-CHECK is the `flycheck-syntax-check' which reported
+STATUS.  STATUS denotes the status of CHECKER, with an optional
+DATA.  STATUS may be one of the following symbols:
+
+`errored'
+     The syntax checker has errored.  DATA is an optional error
+     message.
+
+     This report finishes the current syntax check.
+
+`interrupted'
+     The syntax checker was interrupted.  DATA is ignored.
+
+     This report finishes the current syntax check.
+
+`finished'
+     The syntax checker has finished with a proper error report
+     for the current buffer.  DATA is the (potentially empty)
+     list of `flycheck-error' objects reported by the syntax
+     check.
+
+     This report finishes the current syntax check.
+
+`suspicious'
+     The syntax checker encountered a suspicious state, which the
+     user needs to be informed about.  DATA is an optional
+     message.
+
+A syntax checker _must_ report a status at least once with any
+symbol that finishes the current syntax checker.  Otherwise
+Flycheck gets stuck with the current syntax check.
+
+If CHECKER is not the currently used syntax checker in
+`flycheck-current-syntax-check', the status report is largely
+ignored.  Notably, any errors reported by the checker are
+discarded."
+  (let ((buffer (flycheck-syntax-check-buffer syntax-check)))
+    ;; Ignore the status report if the buffer is gone, or if this syntax check
+    ;; isn't the current one in buffer (which can happen if this is an old
+    ;; report of an interrupted syntax check, and a new syntax check was started
+    ;; since this check was interrupted)
+    (when (and (buffer-live-p buffer)
+               (eq syntax-check
+                   (buffer-local-value 'flycheck-current-syntax-check buffer)))
+      (with-current-buffer buffer
+        (let ((checker (flycheck-syntax-check-checker syntax-check)))
+          (pcase status
+            ((or `errored `interrupted)
+             (flycheck-report-failed-syntax-check status)
+             (when (eq status 'errored)
+               ;; In case of error, show the error message
+               (message "Error from syntax checker %s: %s"
+                        checker (or data "UNKNOWN!"))))
+            (`suspicious
+             (when flycheck-mode
+               (message "Suspicious state from syntax checker %s: %s"
+                        checker (or data "UNKNOWN!")))
+             (flycheck-report-status 'suspicious))
+            (`finished
+             (when flycheck-mode
+               ;; Only report errors from the checker if Flycheck Mode is
+               ;; still enabled.
+               (flycheck-finish-current-syntax-check
+                data
+                (flycheck-syntax-check-working-directory syntax-check))))
+            (_
+             (error "Unknown status %s from syntax checker %s"
+                    status checker))))))))
+
+(defun flycheck-finish-current-syntax-check (errors working-dir)
+  "Finish the current syntax-check in the current buffer with ERRORS.
+
+ERRORS is a list of `flycheck-error' objects reported by the
+current syntax check in `flycheck-current-syntax-check'.
+
+Report all ERRORS and potentially start any next syntax checkers.
+
+If the current syntax checker reported excessive errors, it is
+disabled via `flycheck-disable-excessive-checker' for subsequent
+syntax checks.
+
+Relative file names in ERRORS will be expanded relative to
+WORKING-DIR."
+  (let* ((syntax-check flycheck-current-syntax-check)
+         (checker (flycheck-syntax-check-checker syntax-check))
+         (errors (flycheck-relevant-errors
+                  (flycheck-fill-and-expand-error-file-names
+                   (flycheck-filter-errors
+                    (flycheck-assert-error-list-p errors) checker)
+                   working-dir))))
+    (unless (flycheck-disable-excessive-checker checker errors)
+      (flycheck-report-current-errors errors))
+    (let ((next-checker (flycheck-get-next-checker-for-buffer checker)))
+      (if next-checker
+          (flycheck-start-current-syntax-check next-checker)
+        (setq flycheck-current-syntax-check nil)
+        (flycheck-report-status 'finished)
+        ;; Delete overlays only after the very last checker has run, to avoid
+        ;; flickering on intermediate re-displays
+        (flycheck-delete-marked-overlays)
+        (flycheck-error-list-refresh)
+        (run-hooks 'flycheck-after-syntax-check-hook)
+        (when (eq (current-buffer) (window-buffer))
+          (flycheck-display-error-at-point))
+        ;; Immediately try to run any pending deferred syntax check, which
+        ;; were triggered by intermediate automatic check event, to make sure
+        ;; that we quickly refine outdated error information
+        (flycheck-perform-deferred-syntax-check)))))
+
+(defun flycheck-disable-excessive-checker (checker errors)
+  "Disable CHECKER if it reported excessive ERRORS.
+
+If ERRORS has more items than `flycheck-checker-error-threshold',
+add CHECKER to `flycheck-disabled-checkers', and show a warning.
+
+Return t when CHECKER was disabled, or nil otherwise."
+  (when (and flycheck-checker-error-threshold
+             (> (length errors) flycheck-checker-error-threshold))
+    ;; Disable CHECKER for this buffer (`flycheck-disabled-checkers' is a local
+    ;; variable).
+    (lwarn '(flycheck syntax-checker) :warning
+           "Syntax checker %s reported too many errors (%s) and is disabled."
+           checker (length errors))
+    (push checker flycheck-disabled-checkers)
+    t))
+
+(defun flycheck-clear (&optional shall-interrupt)
+  "Clear all errors in the current buffer.
+
+With prefix arg or SHALL-INTERRUPT non-nil, also interrupt the
+current syntax check."
+  (interactive "P")
+  (when shall-interrupt
+    (flycheck-stop))
+  (flycheck-delete-all-overlays)
+  (flycheck-clear-errors)
+  (flycheck-error-list-refresh)
+  (flycheck-hide-error-buffer))
+
+(defun flycheck-teardown ()
+  "Teardown Flycheck in the current buffer..
+
+Completely clear the whole Flycheck state.  Remove overlays, kill
+running checks, and empty all variables used by Flycheck."
+  (flycheck-safe-delete-temporaries)
+  (flycheck-stop)
+  (flycheck-clean-deferred-check)
+  (flycheck-clear)
+  (flycheck-cancel-error-display-error-at-point-timer))
+
+
+;;; Automatic syntax checking in a buffer
+(defun flycheck-may-check-automatically (&optional condition)
+  "Determine whether the buffer may be checked under CONDITION.
+
+Read-only buffers may never be checked automatically.
+
+If CONDITION is non-nil, determine whether syntax may checked
+automatically according to
+`flycheck-check-syntax-automatically'."
+  (and (not (or buffer-read-only (flycheck-ephemeral-buffer-p)))
+       (file-exists-p default-directory)
+       (or (not condition)
+           (memq condition flycheck-check-syntax-automatically))))
+
+(defun flycheck-buffer-automatically (&optional condition force-deferred)
+  "Automatically check syntax at CONDITION.
+
+Syntax is not checked if `flycheck-may-check-automatically'
+returns nil for CONDITION.
+
+The syntax check is deferred if FORCE-DEFERRED is non-nil, or if
+`flycheck-must-defer-check' returns t."
+  (when (and flycheck-mode (flycheck-may-check-automatically condition))
+    (if (or force-deferred (flycheck-must-defer-check))
+        (flycheck-buffer-deferred)
+      (with-demoted-errors "Error while checking syntax automatically: %S"
+        (flycheck-buffer)))))
+
+(defvar-local flycheck-idle-change-timer nil
+  "Timer to mark the idle time since the last change.")
+
+(defun flycheck-clear-idle-change-timer ()
+  "Clear the idle change timer."
+  (when flycheck-idle-change-timer
+    (cancel-timer flycheck-idle-change-timer)
+    (setq flycheck-idle-change-timer nil)))
+
+(defun flycheck-handle-change (beg end _len)
+  "Handle a buffer change between BEG and END.
+
+BEG and END mark the beginning and end of the change text.  _LEN
+is ignored.
+
+Start a syntax check if a new line has been inserted into the
+buffer."
+  ;; Save and restore the match data, as recommended in (elisp)Change Hooks
+  (save-match-data
+    (when flycheck-mode
+      ;; The buffer was changed, thus clear the idle timer
+      (flycheck-clear-idle-change-timer)
+      (if (string-match-p (rx "\n") (buffer-substring beg end))
+          (flycheck-buffer-automatically 'new-line 'force-deferred)
+        (setq flycheck-idle-change-timer
+              (run-at-time flycheck-idle-change-delay nil
+                           #'flycheck--handle-idle-change-in-buffer
+                           (current-buffer)))))))
+
+(defun flycheck--handle-idle-change-in-buffer (buffer)
+  "Handle an expired idle timer in BUFFER since the last change.
+This thin wrapper around `flycheck-handle-idle-change' is needed
+because some users override that function, as described in URL
+`https://github.com/flycheck/flycheck/pull/1305'."
+  (when (buffer-live-p buffer)
+    (with-current-buffer buffer
+      (flycheck-handle-idle-change))))
+
+(defun flycheck-handle-idle-change ()
+  "Handle an expired idle timer since the last change."
+  (flycheck-clear-idle-change-timer)
+  (flycheck-buffer-automatically 'idle-change))
+
+(defun flycheck-handle-save ()
+  "Handle a save of the buffer."
+  (flycheck-buffer-automatically 'save))
+
+
+;;; Deferred syntax checking
+(defvar-local flycheck-deferred-syntax-check nil
+  "If non-nil, a deferred syntax check is pending.")
+
+(defun flycheck-must-defer-check ()
+  "Determine whether the syntax check has to be deferred.
+
+A check has to be deferred if the buffer is not visible, or if the buffer is
+currently being reverted.
+
+Return t if the check is to be deferred, or nil otherwise."
+  (or (not (get-buffer-window))
+      ;; We defer the syntax check if Flycheck is already running, to
+      ;; immediately start a new syntax check after the current one finished,
+      ;; because the result of the current check will most likely be outdated by
+      ;; the time it is finished.
+      (flycheck-running-p)
+      ;; We must defer checks while a buffer is being reverted, to avoid race
+      ;; conditions while the buffer contents are being restored.
+      revert-buffer-in-progress-p))
+
+(defun flycheck-deferred-check-p ()
+  "Determine whether the current buffer has a deferred check.
+
+Return t if so, or nil otherwise."
+  flycheck-deferred-syntax-check)
+
+(defun flycheck-buffer-deferred ()
+  "Defer syntax check for the current buffer."
+  (setq flycheck-deferred-syntax-check t))
+
+(defun flycheck-clean-deferred-check ()
+  "Clean a deferred syntax checking state."
+  (setq flycheck-deferred-syntax-check nil))
+
+(defun flycheck-perform-deferred-syntax-check ()
+  "Perform the deferred syntax check."
+  (when (flycheck-deferred-check-p)
+    (flycheck-clean-deferred-check)
+    (flycheck-buffer-automatically)))
+
+
+;;; Syntax checking in all buffers
+(defun flycheck-may-enable-mode ()
+  "Determine whether Flycheck mode may be enabled.
+
+Flycheck mode is not enabled for
+
+- the minibuffer,
+- `fundamental-mode'
+- major modes whose `mode-class' property is `special',
+- ephemeral buffers (see `flycheck-ephemeral-buffer-p'),
+- encrypted buffers (see `flycheck-encrypted-buffer-p'),
+- remote files (see `file-remote-p'),
+- and major modes excluded by `flycheck-global-modes'.
+
+Return non-nil if Flycheck mode may be enabled, and nil
+otherwise."
+  (and (pcase flycheck-global-modes
+         ;; Whether `major-mode' is disallowed by `flycheck-global-modes'
+         (`t t)
+         (`(not . ,modes) (not (memq major-mode modes)))
+         (modes (memq major-mode modes)))
+       (not (or (minibufferp)
+                (eq major-mode 'fundamental-mode)
+                (eq (get major-mode 'mode-class) 'special)
+                (flycheck-ephemeral-buffer-p)
+                (flycheck-encrypted-buffer-p)
+                (and (buffer-file-name)
+                     (file-remote-p (buffer-file-name) 'method))))))
+
+(defun flycheck-mode-on-safe ()
+  "Enable command `flycheck-mode' if it is safe to do so.
+
+Command `flycheck-mode' is only enabled if
+`flycheck-may-enable-mode' returns a non-nil result."
+  (when (flycheck-may-enable-mode)
+    (flycheck-mode)))
+
+;;;###autoload
+(define-globalized-minor-mode global-flycheck-mode flycheck-mode
+  flycheck-mode-on-safe
+  :init-value nil
+  ;; Do not expose Global Flycheck Mode on customize interface, because the
+  ;; interaction between package.el and customize is currently broken.  See
+  ;; https://github.com/flycheck/flycheck/issues/595
+
+  ;; :require 'flycheck :group
+  ;; 'flycheck
+  )
+
+(defun flycheck-global-teardown ()
+  "Teardown Flycheck in all buffers.
+
+Completely clear the whole Flycheck state in all buffers, stop
+all running checks, remove all temporary files, and empty all
+variables of Flycheck."
+  (dolist (buffer (buffer-list))
+    (with-current-buffer buffer
+      (when flycheck-mode
+        (flycheck-teardown)))))
+
+;; Clean up the entire state of Flycheck when Emacs is killed, to get rid of any
+;; pending temporary files.
+(add-hook 'kill-emacs-hook #'flycheck-global-teardown)
+
+
+;;; Errors from syntax checks
+(cl-defstruct (flycheck-error
+               (:constructor flycheck-error-new)
+               (:constructor flycheck-error-new-at
+                             (line column
+                                   &optional level message
+                                   &key checker id group
+                                   (filename (buffer-file-name))
+                                   (buffer (current-buffer)))))
+  "Structure representing an error reported by a syntax checker.
+Slots:
+
+`buffer'
+     The buffer that the error was reported for, as buffer object.
+
+`checker'
+     The syntax checker which reported this error, as symbol.
+
+`filename'
+     The file name the error refers to, as string.
+
+`line'
+     The line number the error refers to, as number.
+
+`column' (optional)
+     The column number the error refers to, as number.
+
+     For compatibility with external tools and unlike Emacs
+     itself (e.g. in Compile Mode) Flycheck uses _1-based_
+     columns: The first character on a line is column 1.
+
+     Occasionally some tools try to proactively adapt to Emacs
+     and emit 0-based columns automatically.  In these cases, the
+     columns must be adjusted for Flycheck, see
+     `flycheck-increment-error-columns'.
+
+`message' (optional)
+     The error message as a string, if any.
+
+`level'
+     The error level, as either `info', `warning' or `error'.
+
+`id' (optional)
+     An ID identifying the kind of error.
+
+`group` (optional)
+     A symbol identifying the group the error belongs to.
+
+     Some tools will emit multiple errors that relate to the same
+     issue (e.g., lifetime errors in Rust).  All related errors
+     collected by a checker should have the same `group` value,
+     in order to be able to present them to the user.
+
+     See `flycheck-related-errors`."
+  buffer checker filename line column message level id group)
+
+(defmacro flycheck-error-with-buffer (err &rest forms)
+  "Switch to the buffer of ERR and evaluate FORMS.
+
+If the buffer of ERR is not live, FORMS are not evaluated."
+  (declare (indent 1) (debug t))
+  `(when (buffer-live-p (flycheck-error-buffer ,err))
+     (with-current-buffer (flycheck-error-buffer ,err)
+       ,@forms)))
+
+(defun flycheck-error-line-region (err)
+  "Get the line region of ERR.
+
+ERR is a Flycheck error whose region to get.
+
+Return a cons cell `(BEG . END)' where BEG is the first
+non-whitespace character on the line ERR refers to, and END the
+end of the line."
+  (flycheck-error-with-buffer err
+    (save-restriction
+      (save-excursion
+        (widen)
+        (goto-char (point-min))
+        (forward-line (- (flycheck-error-line err) 1))
+        ;; We are at the beginning of the line now, so move to the beginning of
+        ;; its indentation, similar to `back-to-indentation'
+        (let ((end (line-end-position)))
+          (skip-syntax-forward " " end)
+          (backward-prefix-chars)
+          ;; If the current line is empty, include the previous line break
+          ;; character(s) to have any region at all.  When called with 0,
+          ;; `line-end-position' gives us the end of the previous line
+          (cons (if (eolp) (line-end-position 0) (point)) end))))))
+
+(defun flycheck-error-column-region (err)
+  "Get the error column region of ERR.
+
+ERR is a Flycheck error whose region to get.
+
+Return a cons cell `(BEG . END)' where BEG is the character
+before the error column, and END the actual error column, or nil
+if ERR has no column."
+  (flycheck-error-with-buffer err
+    (save-restriction
+      (save-excursion
+        (-when-let (column (flycheck-error-column err))
+          (widen)
+          (goto-char (point-min))
+          (forward-line (- (flycheck-error-line err) 1))
+          (cond
+           ((eobp)                    ; Line beyond EOF
+            ;; If we are at the end of the file (i.e. the line was beyond the
+            ;; end of the file), use the very last column in the file.
+            (cons (- (point-max) 1) (point-max)))
+           ((eolp)                    ; Empty line
+            ;; If the target line is empty, there's no column to highlight on
+            ;; this line, so return the last column of the previous line.
+            (cons (line-end-position 0) (point)))
+           (t
+            ;; The end is either the column offset of the line, or the end of
+            ;; the line, if the column offset points beyond the end of the
+            ;; line.
+            (let ((end (min (+ (point) column)
+                            (+ (line-end-position) 1))))
+              (cons (- end 1) end)))))))))
+
+(defun flycheck-error-thing-region (thing err)
+  "Get the region of THING at the column of ERR.
+
+ERR is a Flycheck error whose region to get.  THING is a
+understood by `thing-at-point'.
+
+Return a cons cell `(BEG . END)' where BEG is the beginning of
+the THING at the error column, and END the end of the symbol.  If
+ERR has no error column, or if there is no THING at this column,
+return nil."
+  (-when-let (column (car (flycheck-error-column-region err)))
+    (flycheck-error-with-buffer err
+      (save-excursion
+        (save-restriction
+          (widen)
+          (goto-char column)
+          (bounds-of-thing-at-point thing))))))
+
+(defun flycheck-error-region-for-mode (err mode)
+  "Get the region of ERR for the highlighting MODE.
+
+ERR is a Flycheck error.  MODE may be one of the following symbols:
+
+`columns'
+     Get the column region of ERR, or the line region if ERR
+     has no column.
+
+`symbols'
+     Get the symbol region of ERR, or the result of `columns', if
+     there is no sexp at the error column.
+
+`sexps'
+     Get the sexp region of ERR, or the result of `columns', if
+     there is no sexp at the error column.
+
+`lines'
+     Return the line region.
+
+Otherwise signal an error."
+  ;; Ignoring fields speeds up calls to `line-end-position' in
+  ;; `flycheck-error-column-region' and `flycheck-error-line-region'.
+  (let ((inhibit-field-text-motion t))
+    (pcase mode
+      (`columns (or (flycheck-error-column-region err)
+                    (flycheck-error-line-region err)))
+      (`symbols (or (flycheck-error-thing-region 'symbol err)
+                    (flycheck-error-region-for-mode err 'columns)))
+      (`sexps (or (flycheck-error-thing-region 'sexp err)
+                  (flycheck-error-region-for-mode err 'columns)))
+      (`lines (flycheck-error-line-region err))
+      (_ (error "Invalid mode %S" mode)))))
+
+(defun flycheck-error-pos (err)
+  "Get the buffer position of ERR.
+
+ERR is a Flycheck error whose position to get.
+
+The error position is the error column, or the first
+non-whitespace character of the error line, if ERR has no error column."
+  (car (or (flycheck-error-column-region err)
+           (flycheck-error-line-region err))))
+
+(defun flycheck-error-format-message-and-id (err)
+  "Format the message and id of ERR as human-readable string."
+  (let ((id (flycheck-error-id err))
+        (filename (flycheck-error-filename err)))
+    (concat (when (and filename (not (equal filename (buffer-file-name))))
+              (format "In \"%s\":\n"
+                      (file-relative-name filename default-directory)))
+            (flycheck-error-message err)
+            (when id
+              (format " [%s]" id)))))
+
+(defun flycheck-error-format (err &optional with-file-name)
+  "Format ERR as human-readable string, optionally WITH-FILE-NAME.
+
+Return a string that represents the given ERR.  If WITH-FILE-NAME
+is given and non-nil, include the file-name as well, otherwise
+omit it."
+  (let* ((line (flycheck-error-line err))
+         (column (flycheck-error-column err))
+         (level (symbol-name (flycheck-error-level err)))
+         (checker (symbol-name (flycheck-error-checker err)))
+         (format `(,@(when with-file-name
+                       (list (flycheck-error-filename err) ":"))
+                   ,(number-to-string line) ":"
+                   ,@(when column (list (number-to-string column) ":"))
+                   ,level ": "
+                   ,(flycheck-error-format-message-and-id err)
+                   " (" ,checker ")")))
+    (apply #'concat format)))
+
+(defun flycheck-error-< (err1 err2)
+  "Determine whether ERR1 is less than ERR2 by location.
+
+Compare by line numbers and then by column numbers."
+  (let ((line1 (flycheck-error-line err1))
+        (line2 (flycheck-error-line err2)))
+    (if (= line1 line2)
+        (let ((col1 (flycheck-error-column err1))
+              (col2 (flycheck-error-column err2)))
+          (and col2
+               ;; Sort errors for the whole line first
+               (or (not col1) (< col1 col2))))
+      (< line1 line2))))
+
+(defun flycheck-error-level-< (err1 err2)
+  "Determine whether ERR1 is less than ERR2 by error level.
+
+Like `flycheck-error-<', but compares by error level severity
+first.  Levels of the same severity are compared by name."
+  (let* ((level1 (flycheck-error-level err1))
+         (level2 (flycheck-error-level err2))
+         (severity1 (flycheck-error-level-severity level1))
+         (severity2 (flycheck-error-level-severity level2)))
+    (cond
+     ((= severity1 severity2)
+      (if (string= level1 level2)
+          (flycheck-error-< err1 err2)
+        (string< level1 level2)))
+     (t (< severity1 severity2)))))
+
+(defun flycheck-assert-error-list-p (errors)
+  "Assert that all items in ERRORS are of `flycheck-error' type.
+
+Signal an error if any item in ERRORS is not a `flycheck-error'
+object, as by `flycheck-error-p'.  Otherwise return ERRORS
+again."
+  (unless (listp errors)
+    (signal 'wrong-type-argument (list 'listp errors)))
+  (dolist (err errors)
+    (unless (flycheck-error-p err)
+      (signal 'wrong-type-argument (list 'flycheck-error-p err))))
+  errors)
+
+
+;;; Errors in the current buffer
+(defvar-local flycheck-current-errors nil
+  "A list of all errors and warnings in the current buffer.")
+
+(defun flycheck-report-current-errors (errors)
+  "Report ERRORS in the current buffer.
+
+Add ERRORS to `flycheck-current-errors' and process each error
+with `flycheck-process-error-functions'."
+  (setq flycheck-current-errors (sort (append errors flycheck-current-errors)
+                                      #'flycheck-error-<))
+  (overlay-recenter (point-max))
+  (seq-do (lambda (err)
+            (run-hook-with-args-until-success 'flycheck-process-error-functions
+                                              err))
+          errors))
+
+(defun flycheck-clear-errors ()
+  "Remove all error information from the current buffer."
+  (setq flycheck-current-errors nil)
+  (flycheck-report-status 'not-checked))
+
+(defun flycheck-fill-and-expand-error-file-names (errors directory)
+  "Fill and expand file names in ERRORS relative to DIRECTORY.
+
+Expand all file names of ERRORS against DIRECTORY.  If the file
+name of an error is nil fill in the result of function
+`buffer-file-name' in the current buffer.
+
+Return ERRORS, modified in-place."
+  (seq-do (lambda (err)
+            (setf (flycheck-error-filename err)
+                  (-if-let (filename (flycheck-error-filename err))
+                      (expand-file-name filename directory)
+                    (buffer-file-name))))
+          errors)
+  errors)
+
+(defun flycheck-relevant-error-other-file-p (err)
+  "Determine whether ERR is a relevant error for another file."
+  (let ((file-name (flycheck-error-filename err)))
+    (and file-name
+         (or (null buffer-file-name)
+             (not (flycheck-same-files-p buffer-file-name file-name)))
+         (eq 'error (flycheck-error-level err)))))
+
+(defun flycheck-relevant-error-p (err)
+  "Determine whether ERR is relevant for the current buffer.
+
+Return t if ERR may be shown for the current buffer, or nil
+otherwise."
+  (flycheck-error-with-buffer err
+    (let ((file-name (flycheck-error-filename err))
+          (message (flycheck-error-message err)))
+      (and
+       (or
+        ;; Neither the error nor buffer have a file name
+        (and (not file-name) (not buffer-file-name))
+        ;; Both have files, and they match
+        (and buffer-file-name file-name
+             (flycheck-same-files-p file-name buffer-file-name))
+        ;; This is a significant error from another file
+        (flycheck-relevant-error-other-file-p err))
+       message
+       (not (string-empty-p message))
+       (flycheck-error-line err)))))
+
+(defun flycheck-relevant-errors (errors)
+  "Filter the relevant errors from ERRORS.
+
+Return a list of all errors that are relevant for their
+corresponding buffer."
+  (seq-filter #'flycheck-relevant-error-p errors))
+
+(defun flycheck-related-errors (err &optional error-set)
+  "Get all the errors that are in the same group as ERR.
+
+Return a list of all errors (from ERROR-SET) that have the same
+`flycheck-error-group' as ERR, including ERR itself.
+
+If ERROR-SET is nil, `flycheck-current-errors' is used instead."
+  (let ((group (flycheck-error-group err))
+        (checker (flycheck-error-checker err)))
+    (if group
+        (seq-filter (lambda (e)
+                      (and (eq (flycheck-error-checker e) checker)
+                           (eq (flycheck-error-group e) group)))
+                    (or error-set flycheck-current-errors))
+      (list err))))
+
+
+;;; Status reporting for the current buffer
+(defvar-local flycheck-last-status-change 'not-checked
+  "The last status change in the current buffer.")
+
+(defun flycheck-report-failed-syntax-check (&optional status)
+  "Report a failed Flycheck syntax check with STATUS.
+
+STATUS is a status symbol for `flycheck-report-status',
+defaulting to `errored'.
+
+Clear Flycheck state, run `flycheck-syntax-check-failed-hook' and
+report an error STATUS."
+  (flycheck-clear)
+  (setq flycheck-current-syntax-check nil)
+  (run-hooks 'flycheck-syntax-check-failed-hook)
+  (flycheck-report-status (or status 'errored)))
+
+(defun flycheck-report-status (status)
+  "Report Flycheck STATUS.
+
+STATUS is one of the following symbols:
+
+`not-checked'
+     The current buffer was not checked.
+
+`no-checker'
+     Automatic syntax checker selection did not find a suitable
+     syntax checker.
+
+`running'
+     A syntax check is now running in the current buffer.
+
+`errored'
+     The current syntax check has errored.
+
+`finished'
+     The current syntax check was finished normally.
+
+`interrupted'
+     The current syntax check was interrupted.
+
+`suspicious'
+     The last syntax check had a suspicious result.
+
+Set `flycheck-last-status-change' and call
+`flycheck-status-changed-functions' with STATUS.  Afterwards
+refresh the mode line."
+  (setq flycheck-last-status-change status)
+  (run-hook-with-args 'flycheck-status-changed-functions status)
+  (force-mode-line-update))
+
+(defun flycheck-mode-line-status-text (&optional status)
+  "Get a text describing STATUS for use in the mode line.
+
+STATUS defaults to `flycheck-last-status-change' if omitted or
+nil."
+  (let ((text (pcase (or status flycheck-last-status-change)
+                (`not-checked "")
+                (`no-checker "-")
+                (`running "*")
+                (`errored "!")
+                (`finished
+                 (let-alist (flycheck-count-errors flycheck-current-errors)
+                   (if (or .error .warning)
+                       (format ":%s/%s" (or .error 0) (or .warning 0))
+                     "")))
+                (`interrupted ".")
+                (`suspicious "?"))))
+    (concat " " flycheck-mode-line-prefix text)))
+
+
+;;; Error levels
+;;;###autoload
+(defun flycheck-define-error-level (level &rest properties)
+  "Define a new error LEVEL with PROPERTIES.
+
+The following PROPERTIES constitute an error level:
+
+`:severity SEVERITY'
+     A number denoting the severity of this level.  The higher
+     the number, the more severe is this level compared to other
+     levels.  Defaults to 0.
+
+     The severity is used by `flycheck-error-level-<' to
+     determine the ordering of errors according to their levels.
+
+`:compilation-level LEVEL'
+
+     A number indicating the broad class of messages that errors
+     at this level belong to: one of 0 (info), 1 (warning), or
+     2 or nil (error).  Defaults to nil.
+
+     This is used by `flycheck-checker-pattern-to-error-regexp'
+     to map error levels into `compilation-mode''s hierarchy and
+     to get proper highlighting of errors in `compilation-mode'.
+
+`:overlay-category CATEGORY'
+     A symbol denoting the overlay category to use for error
+     highlight overlays for this level.  See Info
+     node `(elisp)Overlay Properties' for more information about
+     overlay categories.
+
+     A category for an error level overlay should at least define
+     the `face' property, for error highlighting.  Another useful
+     property for error level categories is `priority', to
+     influence the stacking of multiple error level overlays.
+
+`:fringe-bitmap BITMAP'
+     A fringe bitmap symbol denoting the bitmap to use for fringe
+     indicators for this level.  See Info node `(elisp)Fringe
+     Bitmaps' for more information about fringe bitmaps,
+     including a list of built-in fringe bitmaps.
+
+`:fringe-face FACE'
+     A face symbol denoting the face to use for fringe indicators
+     for this level.
+
+`:error-list-face FACE'
+     A face symbol denoting the face to use for messages of this
+     level in the error list.  See `flycheck-list-errors'."
+  (declare (indent 1))
+  (setf (get level 'flycheck-error-level) t)
+  (setf (get level 'flycheck-error-severity)
+        (or (plist-get properties :severity) 0))
+  (setf (get level 'flycheck-compilation-level)
+        (plist-get properties :compilation-level))
+  (setf (get level 'flycheck-overlay-category)
+        (plist-get properties :overlay-category))
+  (setf (get level 'flycheck-fringe-bitmap-double-arrow)
+        (plist-get properties :fringe-bitmap))
+  (setf (get level 'flycheck-fringe-face)
+        (plist-get properties :fringe-face))
+  (setf (get level 'flycheck-error-list-face)
+        (plist-get properties :error-list-face)))
+
+(defun flycheck-error-level-p (level)
+  "Determine whether LEVEL is a Flycheck error level."
+  (get level 'flycheck-error-level))
+
+(defun flycheck-error-level-severity (level)
+  "Get the numeric severity of LEVEL."
+  (or (get level 'flycheck-error-severity) 0))
+
+(defun flycheck-error-level-compilation-level (level)
+  "Get the compilation level for LEVEL."
+  (get level 'flycheck-compilation-level))
+
+(defun flycheck-error-level-overlay-category (level)
+  "Get the overlay category for LEVEL."
+  (get level 'flycheck-overlay-category))
+
+(defun flycheck-error-level-fringe-bitmap (level)
+  "Get the fringe bitmap for LEVEL."
+  (get level 'flycheck-fringe-bitmap-double-arrow))
+
+(defun flycheck-error-level-fringe-face (level)
+  "Get the fringe face for LEVEL."
+  (get level 'flycheck-fringe-face))
+
+(defun flycheck-error-level-error-list-face (level)
+  "Get the error list face for LEVEL."
+  (get level 'flycheck-error-list-face))
+
+(defun flycheck-error-level-make-fringe-icon (level side)
+  "Create the fringe icon for LEVEL at SIDE.
+
+Return a propertized string that shows a fringe bitmap according
+to LEVEL and the given fringe SIDE.
+
+LEVEL is a Flycheck error level defined with
+`flycheck-define-error-level', and SIDE is either `left-fringe'
+or `right-fringe'.
+
+Return a propertized string representing the fringe icon,
+intended for use as `before-string' of an overlay to actually
+show the icon."
+  (unless (memq side '(left-fringe right-fringe))
+    (error "Invalid fringe side: %S" side))
+  (propertize "!" 'display
+              (list side
+                    (flycheck-error-level-fringe-bitmap level)
+                    (flycheck-error-level-fringe-face level))))
+
+
+;;; Built-in error levels
+(when (fboundp 'define-fringe-bitmap)
+  (define-fringe-bitmap 'flycheck-fringe-bitmap-double-arrow
+    (vector #b00000000
+            #b00000000
+            #b00000000
+            #b00000000
+            #b00000000
+            #b10011000
+            #b01101100
+            #b00110110
+            #b00011011
+            #b00110110
+            #b01101100
+            #b10011000
+            #b00000000
+            #b00000000
+            #b00000000
+            #b00000000
+            #b00000000)))
+
+(setf (get 'flycheck-error-overlay 'face) 'flycheck-error)
+(setf (get 'flycheck-error-overlay 'priority) 110)
+
+(flycheck-define-error-level 'error
+  :severity 100
+  :compilation-level 2
+  :overlay-category 'flycheck-error-overlay
+  :fringe-bitmap 'flycheck-fringe-bitmap-double-arrow
+  :fringe-face 'flycheck-fringe-error
+  :error-list-face 'flycheck-error-list-error)
+
+(setf (get 'flycheck-warning-overlay 'face) 'flycheck-warning)
+(setf (get 'flycheck-warning-overlay 'priority) 100)
+
+(flycheck-define-error-level 'warning
+  :severity 10
+  :compilation-level 1
+  :overlay-category 'flycheck-warning-overlay
+  :fringe-bitmap 'flycheck-fringe-bitmap-double-arrow
+  :fringe-face 'flycheck-fringe-warning
+  :error-list-face 'flycheck-error-list-warning)
+
+(setf (get 'flycheck-info-overlay 'face) 'flycheck-info)
+(setf (get 'flycheck-info-overlay 'priority) 90)
+
+(flycheck-define-error-level 'info
+  :severity -10
+  :compilation-level 0
+  :overlay-category 'flycheck-info-overlay
+  :fringe-bitmap 'flycheck-fringe-bitmap-double-arrow
+  :fringe-face 'flycheck-fringe-info
+  :error-list-face 'flycheck-error-list-info)
+
+
+;;; Error filtering
+(defun flycheck-filter-errors (errors checker)
+  "Filter ERRORS from CHECKER.
+
+Apply the error filter of CHECKER to ERRORs and return the
+result.  If CHECKER has no error filter, fall back to
+`flycheck-sanitize-errors'."
+  (let ((filter (or (flycheck-checker-get checker 'error-filter)
+                    #'flycheck-sanitize-errors)))
+    (funcall filter errors)))
+
+(defun flycheck-sanitize-errors (errors)
+  "Sanitize ERRORS.
+
+Sanitize ERRORS by trimming leading and trailing whitespace in
+all error messages, and by replacing 0 columns and empty error
+messages with nil.
+
+Returns sanitized ERRORS."
+  (dolist (err errors)
+    (flycheck-error-with-buffer err
+      (let ((message (flycheck-error-message err))
+            (column (flycheck-error-column err))
+            (id (flycheck-error-id err)))
+        (when message
+          (setq message (string-trim message))
+          (setf (flycheck-error-message err)
+                (if (string-empty-p message) nil message)))
+        (when (and id (string-empty-p id))
+          (setf (flycheck-error-id err) nil))
+        (when (eq column 0)
+          (setf (flycheck-error-column err) nil)))))
+  errors)
+
+(defun flycheck-remove-error-file-names (file-name errors)
+  "Remove matching FILE-NAME from ERRORS.
+
+Use as `:error-filter' for syntax checkers that output faulty
+filenames.  Flycheck will later fill in the buffer file name.
+
+Return ERRORS."
+  (seq-do (lambda (err)
+            (when (and (flycheck-error-filename err)
+                       (string= (flycheck-error-filename err) file-name))
+              (setf (flycheck-error-filename err) nil)))
+          errors)
+  errors)
+
+(defun flycheck-increment-error-columns (errors &optional offset)
+  "Increment all columns of ERRORS by OFFSET.
+
+Use this as `:error-filter' if a syntax checker outputs 0-based
+columns."
+  (seq-do (lambda (err)
+            (let ((column (flycheck-error-column err)))
+              (when column
+                (setf (flycheck-error-column err)
+                      (+ column (or offset 1))))))
+          errors)
+  errors)
+
+(defun flycheck-collapse-error-message-whitespace (errors)
+  "Collapse whitespace in all messages of ERRORS.
+
+Return ERRORS."
+  (dolist (err errors)
+    (-when-let (message (flycheck-error-message err))
+      (setf (flycheck-error-message err)
+            (replace-regexp-in-string (rx (one-or-more (any space "\n" "\r")))
+                                      " " message 'fixed-case 'literal))))
+  errors)
+
+(defun flycheck-dedent-error-messages (errors)
+  "Dedent all messages of ERRORS.
+
+For each error in ERRORS, determine the indentation offset from
+the leading whitespace of the first line, and dedent all further
+lines accordingly.
+
+Return ERRORS, with in-place modifications."
+  (dolist (err errors)
+    (-when-let (message (flycheck-error-message err))
+      (with-temp-buffer
+        (insert message)
+        ;; Determine the indentation offset
+        (goto-char (point-min))
+        (back-to-indentation)
+        (let* ((indent-offset (- (point) (point-min))))
+          ;; Now iterate over all lines and dedent each according to
+          ;; `indent-offset'
+          (while (not (eobp))
+            (back-to-indentation)
+            ;; If the current line starts with sufficient whitespace, delete the
+            ;; indendation offset.  Otherwise keep the line intact, as we might
+            ;; loose valuable information
+            (when (>= (- (point) (line-beginning-position)) indent-offset)
+              (delete-char (- indent-offset)))
+            (forward-line 1)))
+        (delete-trailing-whitespace (point-min) (point-max))
+        (setf (flycheck-error-message err)
+              (buffer-substring-no-properties (point-min) (point-max))))))
+  errors)
+
+(defun flycheck-fold-include-levels (errors sentinel-message)
+  "Fold levels of ERRORS from included files.
+
+ERRORS is a list of `flycheck-error' objects.  SENTINEL-MESSAGE
+is a regular expression matched against the error message to
+determine whether the errror denotes errors from an included
+file.  Alternatively, it is a function that is given an error and
+shall return non-nil, if the error denotes errors from an
+included file."
+  (unless (or (stringp sentinel-message) (functionp sentinel-message))
+    (error "Sentinel must be string or function: %S" sentinel-message))
+  (let ((sentinel (if (functionp sentinel-message)
+                      sentinel-message
+                    (lambda (err)
+                      (string-match-p sentinel-message
+                                      (flycheck-error-message err)))))
+        (remaining-errors errors))
+    (while remaining-errors
+      (let* ((current-error (pop remaining-errors)))
+        (when (funcall sentinel current-error)
+          ;; We found an error denoting errors in the included file:
+          ;; 1. process all subsequent errors until faulty include file is found
+          ;; 2. process again all subsequent errors until an error has the
+          ;;    current file name again
+          ;; 3. find the most severe error level
+          (let ((current-filename (flycheck-error-filename current-error))
+                (current-level nil)
+                (faulty-include-filename nil)
+                (filename nil)
+                (done (null remaining-errors)))
+
+            (while (not done)
+              (setq filename (flycheck-error-filename (car remaining-errors)))
+              (unless faulty-include-filename
+                (unless (string= filename current-filename)
+                  (setq faulty-include-filename filename)))
+
+              (let* ((error-in-include (pop remaining-errors))
+                     (in-include-level (flycheck-error-level error-in-include)))
+                (unless (funcall sentinel error-in-include)
+                  ;; Ignore nested "included file" errors, we are only
+                  ;; interested in real errors because these define our level
+                  (when (or (not current-level)
+                            (> (flycheck-error-level-severity in-include-level)
+                               (flycheck-error-level-severity current-level)))
+                    (setq current-level in-include-level))))
+
+              (setq done (or (null remaining-errors)
+                             (and faulty-include-filename
+                                  (string= filename current-filename)))))
+
+            (setf (flycheck-error-level current-error) current-level
+                  (flycheck-error-message current-error)
+                  (format "In include %s" faulty-include-filename))))))
+    errors))
+
+(defun flycheck-dequalify-error-ids (errors)
+  "De-qualify error ids in ERRORS.
+
+Remove all qualifications from error ids in ERRORS, by stripping
+all leading dotted components from error IDs.  For instance, if
+the error ID is com.foo.E100, replace it with E100.
+
+This error filter is mainly useful to simplify error IDs obtained
+from parsing Checkstyle XML, which frequently has very verbose
+IDs, that include the name of the tool."
+  (seq-do (lambda (err)
+            (let ((id (flycheck-error-id err)))
+              (when id
+                (setf (flycheck-error-id err)
+                      (replace-regexp-in-string
+                       (rx string-start
+                           (group
+                            (optional (zero-or-more not-newline) "."))
+                           (one-or-more (not (any ".")))
+                           string-end)
+                       "" id 'fixedcase 'literal 1)))))
+          errors)
+  errors)
+
+(defun flycheck-remove-error-ids (errors)
+  "Remove all error ids from ERRORS."
+  (seq-do (lambda (err) (setf (flycheck-error-id err) nil)) errors)
+  errors)
+
+(defun flycheck-fill-empty-line-numbers (errors)
+  "Set ERRORS without lines to line 0.
+
+Use as `:error-filter' for syntax checkers that output errors
+without line numbers.
+
+Return ERRORS."
+  (seq-do (lambda (err)
+            (unless (flycheck-error-line err)
+              (setf (flycheck-error-line err) 0)))
+          errors)
+  errors)
+
+
+;;; Error analysis
+(defun flycheck-count-errors (errors)
+  "Count the number of ERRORS, grouped by level..
+
+Return an alist, where each ITEM is a cons cell whose `car' is an
+error level, and whose `cdr' is the number of errors of that
+level."
+  (let (counts-by-level)
+    (dolist (err errors)
+      (let* ((level (flycheck-error-level err))
+             (item (assq level counts-by-level)))
+        (if item
+            (cl-incf (cdr item))
+          (push (cons level 1) counts-by-level))))
+    counts-by-level))
+
+(defun flycheck-has-max-errors-p (errors level)
+  "Check if there is no error in ERRORS more severe than LEVEL."
+  (let ((severity (flycheck-error-level-severity level)))
+    (seq-every-p (lambda (e) (<= (flycheck-error-level-severity
+                                  (flycheck-error-level e))
+                                 severity))
+                 errors)))
+
+(defun flycheck-has-max-current-errors-p (level)
+  "Check if there is no current error more severe than LEVEL."
+  (flycheck-has-max-errors-p flycheck-current-errors level))
+
+(defun flycheck-has-errors-p (errors level)
+  "Determine if there are any ERRORS with LEVEL."
+  (seq-some (lambda (e) (eq (flycheck-error-level e) level)) errors))
+
+(defun flycheck-has-current-errors-p (&optional level)
+  "Determine if the current buffer has errors with LEVEL.
+
+If LEVEL is omitted if the current buffer has any errors at all."
+  (if level
+      (flycheck-has-errors-p flycheck-current-errors level)
+    (and flycheck-current-errors t)))
+
+
+;;; Error overlays in the current buffer
+(defun flycheck-add-overlay (err)
+  "Add overlay for ERR.
+
+Return the created overlay."
+  ;; We must have a proper error region for the sake of fringe indication,
+  ;; error display and error navigation, even if the highlighting is disabled.
+  ;; We erase the highlighting later on in this case
+  (pcase-let* ((`(,beg . ,end)
+                (if (flycheck-relevant-error-other-file-p err)
+                    ;; Display overlays for other-file errors on the first line
+                    (cons (point-min)
+                          (save-excursion (goto-char (point-min))
+                                          (point-at-eol)))
+                  (flycheck-error-region-for-mode
+                   err (or flycheck-highlighting-mode 'lines))))
+               (overlay (make-overlay beg end))
+               (level (flycheck-error-level err))
+               (category (flycheck-error-level-overlay-category level)))
+    (unless (flycheck-error-level-p level)
+      (error "Undefined error level: %S" level))
+    (setf (overlay-get overlay 'flycheck-overlay) t)
+    (setf (overlay-get overlay 'flycheck-error) err)
+    (setf (overlay-get overlay 'category) category)
+    (unless flycheck-highlighting-mode
+      ;; Erase the highlighting from the overlay if requested by the user
+      (setf (overlay-get overlay 'face) nil))
+    (when flycheck-indication-mode
+      (setf (overlay-get overlay 'before-string)
+            (flycheck-error-level-make-fringe-icon
+             level flycheck-indication-mode)))
+    (setf (overlay-get overlay 'help-echo) #'flycheck-help-echo)
+    overlay))
+
+(defun flycheck-help-echo (_window object pos)
+  "Construct a tooltip message.
+
+Most of the actual work is done by calling
+`flycheck-help-echo-function' with the appropriate list of
+errors.  Arguments WINDOW, OBJECT and POS are as described in
+info node `(elisp)Special properties', as this function is
+intended to be used as the 'help-echo property of flycheck error
+overlays."
+  (-when-let (buf (cond ((bufferp object) object)
+                        ((overlayp object) (overlay-buffer object))))
+    (with-current-buffer buf
+      (-when-let* ((fn flycheck-help-echo-function)
+                   (errs (flycheck-overlay-errors-at pos)))
+        (funcall fn errs)))))
+
+(defun flycheck-help-echo-all-error-messages (errs)
+  "Concatenate error messages and ids from ERRS."
+  (mapconcat
+   (lambda (err)
+     (when err
+       (if (flycheck-error-message err)
+           (flycheck-error-format-message-and-id err)
+         (format "Unknown %s" (flycheck-error-level err)))))
+   (reverse errs) "\n\n"))
+
+(defun flycheck-filter-overlays (overlays)
+  "Get all Flycheck overlays from OVERLAYS."
+  (seq-filter (lambda (o) (overlay-get o 'flycheck-overlay)) overlays))
+
+(defun flycheck-overlays-at (pos)
+  "Get all Flycheck overlays at POS."
+  (flycheck-filter-overlays (overlays-at pos)))
+
+(defun flycheck-overlays-in (beg end)
+  "Get all Flycheck overlays between BEG and END."
+  (flycheck-filter-overlays (overlays-in beg end)))
+
+(defun flycheck-overlay-errors-at (pos)
+  "Return a list of all flycheck errors overlayed at POS."
+  (seq-map (lambda (o) (overlay-get o 'flycheck-error))
+           (flycheck-overlays-at pos)))
+
+(defun flycheck-overlay-errors-in (beg end)
+  "Return a list of all flycheck errors overlayed between BEG and END."
+  (seq-map (lambda (o) (overlay-get o 'flycheck-error))
+           (flycheck-overlays-in beg end)))
+
+(defvar-local flycheck-overlays-to-delete nil
+  "Overlays mark for deletion after all syntax checks completed.")
+(put 'flycheck-overlays-to-delete 'permanent-local t)
+
+(defun flycheck-delete-all-overlays ()
+  "Remove all flycheck overlays in the current buffer."
+  (overlay-recenter (point-max))
+  (flycheck-delete-marked-overlays)
+  (save-restriction
+    (widen)
+    (seq-do #'delete-overlay (flycheck-overlays-in (point-min) (point-max)))))
+
+(defun flycheck-mark-all-overlays-for-deletion ()
+  "Mark all current overlays for deletion."
+  (setq flycheck-overlays-to-delete
+        (append (flycheck-overlays-in (point-min) (point-max))
+                flycheck-overlays-to-delete)))
+
+(defun flycheck-delete-marked-overlays ()
+  "Delete all overlays marked for deletion."
+  (overlay-recenter (point-max))
+  (seq-do #'delete-overlay flycheck-overlays-to-delete)
+  (setq flycheck-overlays-to-delete nil))
+
+
+;;; Error navigation in the current buffer
+(defun flycheck-error-level-interesting-at-pos-p (pos)
+  "Check if error severity at POS passes `flycheck-error-level-interesting-p'."
+  (flycheck-error-level-interesting-p (get-char-property pos 'flycheck-error)))
+
+(defun flycheck-error-level-interesting-p (err)
+  "Check if ERR severity is >= `flycheck-navigation-minimum-level'."
+  (when (flycheck-error-p err)
+    (-if-let (min-level flycheck-navigation-minimum-level)
+        (<= (flycheck-error-level-severity min-level)
+            (flycheck-error-level-severity (flycheck-error-level err)))
+      t)))
+
+(defun flycheck-next-error-pos (n &optional reset)
+  "Get the position of the N-th next error.
+
+With negative N, get the position of the (-N)-th previous error
+instead.  With non-nil RESET, search from `point-min', otherwise
+search from the current point.
+
+Return the position of the next or previous error, or nil if
+there is none."
+  (let ((n (or n 1))
+        (pos (if reset (point-min) (point))))
+    (if (>= n 0)
+        ;; Search forwards
+        (while (and pos (> n 0))
+          (setq n (1- n))
+          (when (get-char-property pos 'flycheck-error)
+            ;; Move beyond from the current error if any
+            (setq pos (next-single-char-property-change pos 'flycheck-error)))
+          (while (not (or (= pos (point-max))
+                          (flycheck-error-level-interesting-at-pos-p pos)))
+            ;; Scan for the next error
+            (setq pos (next-single-char-property-change pos 'flycheck-error)))
+          (when (and (= pos (point-max))
+                     (not (flycheck-error-level-interesting-at-pos-p pos)))
+            ;; If we reached the end of the buffer, but no error, we didn't find
+            ;; any
+            (setq pos nil)))
+      ;; Search backwards
+      (while (and pos (< n 0))
+        (setq n (1+ n))
+        ;; Loop until we find an error.  We need to check the position *before*
+        ;; the current one, because `previous-single-char-property-change'
+        ;; always moves to the position *of* the change.
+        (while (not (or (= pos (point-min))
+                        (flycheck-error-level-interesting-at-pos-p (1- pos))))
+          (setq pos (previous-single-char-property-change pos 'flycheck-error)))
+        (when (and (= pos (point-min))
+                   (not (flycheck-error-level-interesting-at-pos-p pos)))
+          ;; We didn't find any error.
+          (setq pos nil))
+        (when pos
+          ;; We found an error, so move to its beginning
+          (setq pos (previous-single-char-property-change pos
+                                                          'flycheck-error)))))
+    pos))
+
+(defun flycheck-next-error-function (n reset)
+  "Visit the N-th error from the current point.
+
+N is the number of errors to advance by, where a negative N
+advances backwards.  With non-nil RESET, advance from the
+beginning of the buffer, otherwise advance from the current
+position.
+
+Intended for use with `next-error-function'."
+  (-if-let* ((pos (flycheck-next-error-pos n reset))
+             (err (get-char-property pos 'flycheck-error)))
+      (flycheck-jump-to-error err)
+    (user-error "No more Flycheck errors")))
+
+(defun flycheck-next-error (&optional n reset)
+  "Visit the N-th error from the current point.
+
+N is the number of errors to advance by, where a negative N
+advances backwards.  With non-nil RESET, advance from the
+beginning of the buffer, otherwise advance from the current
+position."
+  (interactive "P")
+  (when (consp n)
+    ;; Universal prefix argument means reset
+    (setq reset t n nil))
+  (flycheck-next-error-function n reset)
+  (flycheck-display-error-at-point))
+
+(defun flycheck-previous-error (&optional n)
+  "Visit the N-th previous error.
+
+If given, N specifies the number of errors to move backwards by.
+If N is negative, move forwards instead."
+  (interactive "P")
+  (flycheck-next-error (- (or n 1))))
+
+(defun flycheck-first-error (&optional n)
+  "Visit the N-th error from beginning of the buffer.
+
+If given, N specifies the number of errors to move forward from
+the beginning of the buffer."
+  (interactive "P")
+  (flycheck-next-error n 'reset))
+
+
+;;; Listing errors in buffers
+(defconst flycheck-error-list-buffer "*Flycheck errors*"
+  "The name of the buffer to show error lists.")
+
+(defvar flycheck-error-list-mode-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map (kbd "f") #'flycheck-error-list-set-filter)
+    (define-key map (kbd "F") #'flycheck-error-list-reset-filter)
+    (define-key map (kbd "n") #'flycheck-error-list-next-error)
+    (define-key map (kbd "p") #'flycheck-error-list-previous-error)
+    (define-key map (kbd "g") #'flycheck-error-list-check-source)
+    (define-key map (kbd "e") #'flycheck-error-list-explain-error)
+    (define-key map (kbd "RET") #'flycheck-error-list-goto-error)
+    map)
+  "The keymap of `flycheck-error-list-mode'.")
+
+(defun flycheck-error-list-make-last-column (message checker)
+  "Compute contents of the last error list cell.
+
+MESSAGE and CHECKER are displayed in a single column to allow the
+message to stretch arbitrarily far."
+  (let ((checker-name (propertize (symbol-name checker)
+                                  'face 'flycheck-error-list-checker-name)))
+    (format "%s (%s)" message checker-name)))
+
+(defconst flycheck-error-list-format
+  `[("File" 6)
+    ("Line" 5 flycheck-error-list-entry-< :right-align t)
+    ("Col" 3 nil :right-align t)
+    ("Level" 8 flycheck-error-list-entry-level-<)
+    ("ID" 6 t)
+    (,(flycheck-error-list-make-last-column "Message" 'Checker) 0 t)]
+  "Table format for the error list.")
+
+(defconst flycheck-error-list-padding 1
+  "Padding used in error list.")
+
+(defconst flycheck--error-list-msg-offset
+  (seq-reduce
+   (lambda (offset fmt)
+     (pcase-let* ((`(,_ ,width ,_ . ,props) fmt)
+                  (padding (or (plist-get props :pad-right) 1)))
+       (+ offset width padding)))
+   (seq-subseq flycheck-error-list-format 0 -1)
+   flycheck-error-list-padding)
+  "Amount of space to use in `flycheck-flush-multiline-message'.")
+
+(define-derived-mode flycheck-error-list-mode tabulated-list-mode
+  "Flycheck errors"
+  "Major mode for listing Flycheck errors.
+
+\\{flycheck-error-list-mode-map}"
+  (setq tabulated-list-format flycheck-error-list-format
+        ;; Sort by location initially
+        tabulated-list-sort-key (cons "Line" nil)
+        tabulated-list-padding flycheck-error-list-padding
+        tabulated-list-entries #'flycheck-error-list-entries
+        ;; `revert-buffer' updates the mode line for us, so all we need to do is
+        ;; set the corresponding mode line construct.
+        mode-line-buffer-identification flycheck-error-list-mode-line)
+  ;; Guard `truncate-string-ellipsis' for Emacs 24.
+  ;; TODO: Remove when dropping Emacs 24 compatibility
+  (when (boundp 'truncate-string-ellipsis)
+    ;; See https://github.com/flycheck/flycheck/issues/1101
+    (setq-local truncate-string-ellipsis "…"))
+  (tabulated-list-init-header))
+
+(defvar-local flycheck-error-list-source-buffer nil
+  "The current source buffer of the error list.")
+;; Needs to permanently local to preserve the source buffer across buffer
+;; reversions
+(put 'flycheck-error-list-source-buffer 'permanent-local t)
+
+(defun flycheck-error-list-set-source (buffer)
+  "Set BUFFER as the source buffer of the error list."
+  (when (get-buffer flycheck-error-list-buffer)
+    (with-current-buffer flycheck-error-list-buffer
+      ;; Only update the source when required
+      (unless (eq buffer flycheck-error-list-source-buffer)
+        (setq flycheck-error-list-source-buffer buffer)
+        (flycheck-error-list-refresh)))))
+
+(defun flycheck-error-list-update-source ()
+  "Update the source buffer of the error list."
+  (when (not (eq (current-buffer) (get-buffer flycheck-error-list-buffer)))
+    ;; We must not update the source buffer, if the current buffer is the error
+    ;; list itself.
+    (flycheck-error-list-set-source (current-buffer))))
+
+(defun flycheck-error-list-check-source ()
+  "Trigger a syntax check in the source buffer of the error list."
+  (interactive)
+  (let ((buffer (get-buffer flycheck-error-list-source-buffer)))
+    (when (buffer-live-p buffer)
+      (with-current-buffer buffer
+        (flycheck-buffer)))))
+
+(define-button-type 'flycheck-error-list
+  'action #'flycheck-error-list-button-goto-error
+  'help-echo "mouse-2, RET: goto error"
+  'face nil)
+
+(defun flycheck-error-list-button-goto-error (button)
+  "Go to the error at BUTTON."
+  (flycheck-error-list-goto-error (button-start button)))
+
+(define-button-type 'flycheck-error-list-explain-error
+  'action #'flycheck-error-list-button-explain-error
+  'help-echo "mouse-2, RET: explain error")
+
+(defun flycheck-error-list-button-explain-error (button)
+  "Explain the error at BUTTON."
+  (flycheck-error-list-explain-error (button-start button)))
+
+(defsubst flycheck-error-list-make-cell (text &optional face help-echo type)
+  "Make an error list cell with TEXT and FACE.
+
+If FACE is nil don't set a FACE on TEXT.  If TEXT already has
+face properties, do not specify a FACE.  Note though, that if
+TEXT gets truncated it will not inherit any previous face
+properties.  If you expect TEXT to be truncated in the error
+list, do specify a FACE explicitly!
+
+If HELP-ECHO is non-nil, set a help-echo property on TEXT, with
+value HELP-ECHO.  This is convenient if you expect TEXT to be
+truncated.
+
+The cell will have the type TYPE unless TYPE is nil, and the
+default type `flycheck-error-list' will be used instead."
+  (append (list text 'type (if type type
+                             'flycheck-error-list))
+          (and face (list 'face face))
+          (and help-echo (list 'help-echo help-echo))))
+
+(defsubst flycheck-error-list-make-number-cell (number face)
+  "Make a table cell for a NUMBER with FACE.
+
+Convert NUMBER to string, fontify it with FACE and return the
+string with attached text properties."
+  (flycheck-error-list-make-cell
+   (if (numberp number) (number-to-string number) "")
+   face))
+
+(defun flycheck-error-list-make-entry (error)
+  "Make a table cell for the given ERROR.
+
+Return a list with the contents of the table cell."
+  (let* ((level (flycheck-error-level error))
+         (level-face (flycheck-error-level-error-list-face level))
+         (filename (flycheck-error-filename error))
+         (line (flycheck-error-line error))
+         (column (flycheck-error-column error))
+         (message (or (flycheck-error-message error)
+                      (format "Unknown %s" (symbol-name level))))
+         (flushed-msg (flycheck-flush-multiline-message message))
+         (id (flycheck-error-id error))
+         (id-str (if id (format "%s" id) ""))
+         (checker (flycheck-error-checker error))
+         (msg-and-checker
+          (flycheck-error-list-make-last-column flushed-msg checker))
+         (explainer (flycheck-checker-get checker 'error-explainer)))
+    (list error
+          (vector (flycheck-error-list-make-cell
+                   (if filename
+                       (file-name-nondirectory filename)
+                     "")
+                   'flycheck-error-list-filename)
+                  (flycheck-error-list-make-number-cell
+                   line 'flycheck-error-list-line-number)
+                  (flycheck-error-list-make-number-cell
+                   column 'flycheck-error-list-column-number)
+                  (flycheck-error-list-make-cell
+                   (symbol-name (flycheck-error-level error)) level-face)
+                  ;; Error ID use a different face when an error-explainer is
+                  ;; present
+                  (flycheck-error-list-make-cell
+                   id-str (if explainer 'flycheck-error-list-id-with-explainer
+                            'flycheck-error-list-id)
+                   id-str 'flycheck-error-list-explain-error)
+                  (flycheck-error-list-make-cell
+                   msg-and-checker nil msg-and-checker)))))
+
+(defun flycheck-flush-multiline-message (msg)
+  "Prepare error message MSG for display in the error list.
+
+Prepend all lines of MSG except the first with enough space to
+ensure that they line up properly once the message is displayed."
+  (let* ((spc-spec `(space . (:width ,flycheck--error-list-msg-offset)))
+         (spc (propertize " " 'display spc-spec))
+         (rep (concat "\\1" spc "\\2")))
+    (replace-regexp-in-string "\\([\r\n]+\\)\\(.\\)" rep msg)))
+
+(defun flycheck-error-list-current-errors ()
+  "Read the list of errors in `flycheck-error-list-source-buffer'."
+  (when (buffer-live-p flycheck-error-list-source-buffer)
+    (buffer-local-value 'flycheck-current-errors
+                        flycheck-error-list-source-buffer)))
+
+(defun flycheck-error-list-entries ()
+  "Create the entries for the error list."
+  (-when-let* ((errors (flycheck-error-list-current-errors))
+               (filtered (flycheck-error-list-apply-filter errors)))
+    (seq-map #'flycheck-error-list-make-entry filtered)))
+
+(defun flycheck-error-list-entry-< (entry1 entry2)
+  "Determine whether ENTRY1 is before ENTRY2 by location.
+
+See `flycheck-error-<'."
+  (flycheck-error-< (car entry1) (car entry2)))
+
+(defun flycheck-error-list-entry-level-< (entry1 entry2)
+  "Determine whether ENTRY1 is before ENTRY2 by level.
+
+See `flycheck-error-level-<'."
+  (not (flycheck-error-level-< (car entry1) (car entry2))))
+
+(defvar flycheck-error-list-mode-line-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map [mode-line mouse-1]
+      #'flycheck-error-list-mouse-switch-to-source)
+    map)
+  "Keymap for error list mode line.")
+
+(defun flycheck-error-list-propertized-source-name ()
+  "Get the name of the current source buffer for the mode line.
+
+Propertize the name of the current source buffer for use in the
+mode line indication of `flycheck-error-list-mode'."
+  (let ((name (replace-regexp-in-string
+               (rx "%") "%%"
+               (buffer-name flycheck-error-list-source-buffer)
+               'fixed-case 'literal)))
+    (propertize name 'face 'mode-line-buffer-id
+                'mouse-face 'mode-line-highlight
+                'help-echo "mouse-1: switch to source"
+                'local-map flycheck-error-list-mode-line-map)))
+
+(defun flycheck-error-list-mouse-switch-to-source (event)
+  "Switch to the error list source buffer of the EVENT window."
+  (interactive "e")
+  (save-selected-window
+    (when (eventp event)
+      (select-window (posn-window (event-start event))))
+    (when (buffer-live-p flycheck-error-list-source-buffer)
+      (switch-to-buffer flycheck-error-list-source-buffer))))
+
+(defun flycheck-get-error-list-window-list (&optional all-frames)
+  "Get all windows displaying the error list.
+
+ALL-FRAMES specifies the frames to consider, as in
+`get-buffer-window-list'."
+  (-when-let (buf (get-buffer flycheck-error-list-buffer))
+    (get-buffer-window-list buf nil all-frames)))
+
+(defun flycheck-get-error-list-window (&optional all-frames)
+  "Get a window displaying the error list, or nil if none.
+
+ALL-FRAMES specifies the frames to consider, as in
+`get-buffer-window'."
+  (-when-let (buf (get-buffer flycheck-error-list-buffer))
+    (get-buffer-window buf all-frames)))
+
+(defun flycheck-error-list-recenter-at (pos)
+  "Recenter the error list at POS."
+  (dolist (window (flycheck-get-error-list-window-list t))
+    (with-selected-window window
+      (goto-char pos)
+      (let ((recenter-redisplay nil))
+        (recenter)))))
+
+(defun flycheck-error-list-refresh ()
+  "Refresh the current error list.
+
+Add all errors currently reported for the current
+`flycheck-error-list-source-buffer', and recenter the error
+list."
+  ;; We only refresh the error list, when it is visible in a window, and we
+  ;; select this window while reverting, because Tabulated List mode attempts to
+  ;; recenter the error at the old location, so it must have the proper window
+  ;; selected.
+  (-when-let (window (flycheck-get-error-list-window t))
+    (with-selected-window window
+      (revert-buffer))
+    (run-hooks 'flycheck-error-list-after-refresh-hook)
+    (let ((preserve-pos (eq (current-buffer)
+                            (get-buffer flycheck-error-list-buffer))))
+      ;; If the error list is the current buffer, don't recenter when
+      ;; highlighting
+      (flycheck-error-list-highlight-errors preserve-pos))))
+
+(defun flycheck-error-list-mode-line-filter-indicator ()
+  "Create a string representing the current error list filter."
+  (if flycheck-error-list-minimum-level
+      (format " [>= %s]" flycheck-error-list-minimum-level)
+    ""))
+
+(defun flycheck-error-list-set-filter (level)
+  "Restrict the error list to errors at level LEVEL or higher.
+
+LEVEL is either an error level symbol, or nil, to remove the filter."
+  (interactive
+   (list (read-flycheck-error-level
+          "Minimum error level (errors at lower levels will be hidden): ")))
+  (when (and level (not (flycheck-error-level-p level)))
+    (user-error "Invalid level: %s" level))
+  (-when-let (buf (get-buffer flycheck-error-list-buffer))
+    (with-current-buffer buf
+      (setq-local flycheck-error-list-minimum-level level))
+    (flycheck-error-list-refresh)
+    (flycheck-error-list-recenter-at (point-min))))
+
+(defun flycheck-error-list-reset-filter ()
+  "Remove filters and show all errors in the error list."
+  (interactive)
+  (kill-local-variable 'flycheck-error-list-minimum-level))
+
+(defun flycheck-error-list-apply-filter (errors)
+  "Filter ERRORS according to `flycheck-error-list-minimum-level'."
+  (-if-let* ((min-level flycheck-error-list-minimum-level)
+             (min-severity (flycheck-error-level-severity min-level)))
+      (seq-filter (lambda (err) (>= (flycheck-error-level-severity
+                                     (flycheck-error-level err))
+                                    min-severity))
+                  errors)
+    errors))
+
+(defun flycheck-error-list-goto-error (&optional pos)
+  "Go to the location of the error at POS in the error list.
+
+POS defaults to `point'."
+  (interactive)
+  (-when-let* ((error (tabulated-list-get-id pos)))
+    (flycheck-jump-to-error error)))
+
+(defun flycheck-jump-to-error (error)
+  "Go to the location of ERROR."
+  (let* ((error-copy (copy-flycheck-error error))
+         (filename (flycheck-error-filename error))
+         (other-file-error (flycheck-relevant-error-other-file-p error))
+         (buffer (if filename
+                     (find-file-noselect filename)
+                   (flycheck-error-buffer error))))
+    (when (buffer-live-p buffer)
+      (setf (flycheck-error-buffer error-copy) buffer)
+      (flycheck-jump-in-buffer buffer error-copy)
+      ;; When jumping to an error in another file, it may not have
+      ;; this error available for highlighting yet, so we trigger a check
+      ;; if necessary.
+      (when other-file-error
+        (with-current-buffer buffer
+          (unless (seq-contains flycheck-current-errors error-copy 'equal)
+            (when flycheck-mode
+              (flycheck-buffer))))))))
+
+(defun flycheck-jump-in-buffer (buffer error)
+  "In BUFFER, jump to ERROR."
+  ;; FIXME: we assume BUFFER and the buffer of ERROR are the same.  We don't
+  ;; need the first argument then.
+  (if (eq (window-buffer) (get-buffer flycheck-error-list-buffer))
+      ;; When called from within the error list, keep the error list,
+      ;; otherwise replace the current buffer.
+      (pop-to-buffer buffer 'other-window)
+    (switch-to-buffer buffer))
+  (let ((pos (flycheck-error-pos error)))
+    (unless (eq (goto-char pos) (point))
+      ;; If widening gets in the way of moving to the right place, remove it
+      ;; and try again
+      (widen)
+      (goto-char pos)))
+  ;; Re-highlight the errors
+  (flycheck-error-list-highlight-errors 'preserve-pos))
+
+(defun flycheck-error-list-explain-error (&optional pos)
+  "Explain the error at POS in the error list.
+
+POS defaults to `point'."
+  (interactive)
+  (-when-let* ((error (tabulated-list-get-id pos))
+               (explainer (flycheck-checker-get (flycheck-error-checker error)
+                                                'error-explainer))
+               (explanation (funcall explainer error)))
+    (flycheck-display-error-explanation explanation)))
+
+(defun flycheck-error-list-next-error-pos (pos &optional n)
+  "Starting from POS get the N'th next error in the error list.
+
+N defaults to 1.  If N is negative, search for the previous error
+instead.
+
+Get the beginning position of the N'th next error from POS, or
+nil, if there is no next error."
+  (let ((n (or n 1)))
+    (if (>= n 0)
+        ;; Search forward
+        (while (and pos (/= n 0))
+          (setq n (1- n))
+          (setq pos (next-single-property-change pos 'tabulated-list-id)))
+      ;; Search backwards
+      (while (/= n 0)
+        (setq n (1+ n))
+        ;; We explicitly give the limit here to explicitly have the minimum
+        ;; point returned, to be able to move to the first error (which starts
+        ;; at `point-min')
+        (setq pos (previous-single-property-change pos 'tabulated-list-id
+                                                   nil (point-min)))))
+    pos))
+
+(defun flycheck-error-list-previous-error (n)
+  "Go to the N'th previous error in the error list."
+  (interactive "P")
+  (flycheck-error-list-next-error (- (or n 1))))
+
+(defun flycheck-error-list-next-error (n)
+  "Go to the N'th next error in the error list."
+  (interactive "P")
+  (let ((pos (flycheck-error-list-next-error-pos (point) n)))
+    (when (and pos (/= pos (point)))
+      (goto-char pos)
+      (save-selected-window
+        ;; Keep the error list selected, so that the user can navigate errors by
+        ;; repeatedly pressing n/p, without having to re-select the error list
+        ;; window.
+        (flycheck-error-list-goto-error)))))
+
+(defvar-local flycheck-error-list-highlight-overlays nil
+  "Error highlight overlays in the error list buffer.")
+(put 'flycheck-error-list-highlight-overlays 'permanent-local t)
+
+(defun flycheck-error-list-highlight-errors (&optional preserve-pos)
+  "Highlight errors in the error list.
+
+Highlight all errors in the error lists that are at point in the
+source buffer, and on the same line as point.  Then recenter the
+error list to the highlighted error, unless PRESERVE-POS is
+non-nil."
+  (when (get-buffer flycheck-error-list-buffer)
+    (let ((current-errors (flycheck-overlay-errors-in (line-beginning-position)
+                                                      (line-end-position))))
+      (with-current-buffer flycheck-error-list-buffer
+        (let ((old-overlays flycheck-error-list-highlight-overlays)
+              (min-point (point-max))
+              (max-point (point-min)))
+          ;; Display the new overlays first, to avoid re-display flickering
+          (setq flycheck-error-list-highlight-overlays nil)
+          (when current-errors
+            (let ((next-error-pos (point-min)))
+              (while next-error-pos
+                (let* ((beg next-error-pos)
+                       (end (flycheck-error-list-next-error-pos beg))
+                       (err (tabulated-list-get-id beg)))
+                  (when (member err current-errors)
+                    (setq min-point (min min-point beg)
+                          max-point (max max-point beg))
+                    (let ((ov (make-overlay beg
+                                            ;; Extend overlay to the beginning
+                                            ;; of the next line, to highlight
+                                            ;; the whole line
+                                            (or end (point-max)))))
+                      (push ov flycheck-error-list-highlight-overlays)
+                      (setf (overlay-get ov 'flycheck-error-highlight-overlay)
+                            t)
+                      (setf (overlay-get ov 'face)
+                            'flycheck-error-list-highlight)))
+                  (setq next-error-pos end)))))
+          ;; Delete the old overlays
+          (seq-do #'delete-overlay old-overlays)
+          (when (and (not preserve-pos) current-errors)
+            ;; Move point to the middle error
+            (goto-char (+ min-point (/ (- max-point min-point) 2)))
+            (beginning-of-line)
+            ;; And recenter the error list at this position
+            (flycheck-error-list-recenter-at (point))))))))
+
+(defun flycheck-list-errors ()
+  "Show the error list for the current buffer."
+  (interactive)
+  (unless flycheck-mode
+    (user-error "Flycheck mode not enabled"))
+  ;; Create and initialize the error list
+  (unless (get-buffer flycheck-error-list-buffer)
+    (with-current-buffer (get-buffer-create flycheck-error-list-buffer)
+      (flycheck-error-list-mode)))
+  (flycheck-error-list-set-source (current-buffer))
+  ;; Reset the error filter
+  (flycheck-error-list-reset-filter)
+  ;; Show the error list in a window, and re-select the old window
+  (display-buffer flycheck-error-list-buffer)
+  ;; Finally, refresh the error list to show the most recent errors
+  (flycheck-error-list-refresh))
+
+(defalias 'list-flycheck-errors 'flycheck-list-errors)
+
+
+;;; Displaying errors in the current buffer
+(defun flycheck-display-errors (errors)
+  "Display ERRORS using `flycheck-display-errors-function'."
+  (when flycheck-display-errors-function
+    (funcall flycheck-display-errors-function errors)))
+
+(defvar-local flycheck-display-error-at-point-timer nil
+  "Timer to automatically show the error at point in minibuffer.")
+
+(defun flycheck-cancel-error-display-error-at-point-timer ()
+  "Cancel the error display timer for the current buffer."
+  (when flycheck-display-error-at-point-timer
+    (cancel-timer flycheck-display-error-at-point-timer)
+    (setq flycheck-display-error-at-point-timer nil)))
+
+(defun flycheck-display-error-at-point ()
+  "Display the all error messages at point in minibuffer."
+  (interactive)
+  ;; This function runs from a timer, so we must take care to not ignore any
+  ;; errors
+  (with-demoted-errors "Flycheck error display error: %s"
+    (flycheck-cancel-error-display-error-at-point-timer)
+    (when flycheck-mode
+      (-when-let (errors (flycheck-overlay-errors-at (point)))
+        (flycheck-display-errors errors)))))
+
+(defun flycheck-display-error-at-point-soon ()
+  "Display the first error message at point in minibuffer delayed."
+  (flycheck-cancel-error-display-error-at-point-timer)
+  (when (flycheck-overlays-at (point))
+    (setq flycheck-display-error-at-point-timer
+          (run-at-time flycheck-display-errors-delay nil
+                       'flycheck-display-error-at-point))))
+
+
+;;; Functions to display errors
+(defconst flycheck-error-message-buffer "*Flycheck error messages*"
+  "The name of the buffer to show long error messages in.")
+
+(defun flycheck-error-message-buffer ()
+  "Get the buffer object to show long error messages in.
+
+Get the buffer named by variable `flycheck-error-message-buffer',
+or nil if the buffer does not exist."
+  (get-buffer flycheck-error-message-buffer))
+
+(defun flycheck-may-use-echo-area-p ()
+  "Determine whether the echo area may be used.
+
+The echo area may be used if the cursor is not in the echo area,
+and if the echo area is not occupied by minibuffer input."
+  (not (or cursor-in-echo-area (active-minibuffer-window))))
+
+(defun flycheck-display-error-messages (errors)
+  "Display the messages of ERRORS.
+
+Concatenate all non-nil messages of ERRORS separated by empty
+lines, and display them with `display-message-or-buffer', which
+shows the messages either in the echo area or in a separate
+buffer, depending on the number of lines.  See Info
+node `(elisp)Displaying Messages' for more information.
+
+In the latter case, show messages in the buffer denoted by
+variable `flycheck-error-message-buffer'."
+  (when (and errors (flycheck-may-use-echo-area-p))
+    (let ((messages (seq-map #'flycheck-error-format-message-and-id errors)))
+      (display-message-or-buffer (string-join messages "\n\n")
+                                 flycheck-error-message-buffer
+                                 'not-this-window))))
+
+(defun flycheck-display-error-messages-unless-error-list (errors)
+  "Show messages of ERRORS unless the error list is visible.
+
+Like `flycheck-display-error-messages', but only if the error
+list (see `flycheck-list-errors') is not visible in any window in
+the current frame."
+  (unless (flycheck-get-error-list-window 'current-frame)
+    (flycheck-display-error-messages errors)))
+
+(defun flycheck-hide-error-buffer ()
+  "Hide the Flycheck error buffer if necessary.
+
+Hide the error buffer if there is no error under point."
+  (-when-let* ((buffer (flycheck-error-message-buffer))
+               (window (get-buffer-window buffer)))
+    (unless (flycheck-overlays-at (point))
+      ;; save-selected-window prevents `quit-window' from changing the current
+      ;; buffer (see https://github.com/flycheck/flycheck/issues/648).
+      (save-selected-window
+        (quit-window nil window)))))
+
+
+;;; Working with errors
+(defun flycheck-copy-errors-as-kill (pos &optional formatter)
+  "Copy each error at POS into kill ring, using FORMATTER.
+
+FORMATTER is a function to turn an error into a string,
+defaulting to `flycheck-error-message'.
+
+Interactively, use `flycheck-error-format-message-and-id' as
+FORMATTER with universal prefix arg, and `flycheck-error-id' with
+normal prefix arg, i.e. copy the message and the ID with
+universal prefix arg, and only the id with normal prefix arg."
+  (interactive (list (point)
+                     (pcase current-prefix-arg
+                       ((pred not) #'flycheck-error-message)
+                       ((pred consp) #'flycheck-error-format-message-and-id)
+                       (_ #'flycheck-error-id))))
+  (let ((messages (delq nil (seq-map (or formatter #'flycheck-error-message)
+                                     (flycheck-overlay-errors-at pos)))))
+    (when messages
+      (seq-do #'kill-new (reverse messages))
+      (message (string-join messages "\n")))))
+
+(defun flycheck-explain-error-at-point ()
+  "Display an explanation for the first explainable error at point.
+
+The first explainable error at point is the first error at point
+with a non-nil `:error-explainer' function defined in its
+checker.  The `:error-explainer' function is then called with
+this error to produce the explanation to display."
+  (interactive)
+  (-when-let* ((first-error
+                ;; Get the first error at point that has an `error-explainer'.
+                (seq-find (lambda (error)
+                            (flycheck-checker-get
+                             (flycheck-error-checker error) 'error-explainer))
+                          (flycheck-overlay-errors-at (point))))
+               (explainer
+                (flycheck-checker-get (flycheck-error-checker first-error)
+                                      'error-explainer))
+               (explanation (funcall explainer first-error)))
+    (flycheck-display-error-explanation explanation)))
+
+(defconst flycheck-explain-error-buffer "*Flycheck error explanation*"
+  "The name of the buffer to show error explanations.")
+
+(defun flycheck-display-error-explanation (explanation)
+  "Display the EXPLANATION string in a help buffer."
+  (with-help-window (get-buffer-create flycheck-explain-error-buffer)
+    (princ explanation)))
+
+
+;;; Syntax checkers using external commands
+(defun flycheck-command-argument-p (arg)
+  "Check whether ARG is a valid command argument."
+  (pcase arg
+    ((pred stringp) t)
+    ((or `source `source-inplace `source-original) t)
+    ((or `temporary-directory `temporary-file-name) t)
+    (`null-device t)
+    (`(config-file ,option-name ,config-file-var)
+     (and (stringp option-name)
+          (symbolp config-file-var)))
+    (`(config-file ,option-name ,config-file-var ,prepender)
+     (and (stringp option-name)
+          (symbolp config-file-var)
+          (symbolp prepender)))
+    (`(,(or `option `option-list) ,option-name ,option-var)
+     (and (stringp option-name)
+          (symbolp option-var)))
+    (`(,(or `option `option-list) ,option-name ,option-var ,prepender)
+     (and (stringp option-name)
+          (symbolp option-var)
+          (symbolp prepender)))
+    (`(,(or `option `option-list) ,option-name ,option-var ,prepender ,filter)
+     (and (stringp option-name)
+          (symbolp option-var)
+          (symbolp prepender)
+          (symbolp filter)))
+    (`(option-flag ,option-name ,option-var)
+     (and (stringp option-name)
+          (symbolp option-var)))
+    (`(eval ,_) t)
+    (_ nil)))
+
+(defun flycheck-compute-working-directory (checker)
+  "Get the default working directory for CHECKER.
+
+Compute the value of `default-directory' for the invocation of
+the syntax checker command, by calling the function in the
+`working-directory' property of CHECKER, with CHECKER as sole
+argument, and returning its value.  Signal an error if the
+function returns a non-existing working directory.
+
+If the property is undefined or if the function returns nil
+return the `default-directory' of the current buffer."
+  (let* ((def-directory-fn (flycheck-checker-get checker 'working-directory))
+         (directory (or (and def-directory-fn
+                             (funcall def-directory-fn checker))
+                        ;; Default to the `default-directory' of the current
+                        ;; buffer
+                        default-directory)))
+    (unless (file-exists-p directory)
+      (error ":working-directory %s of syntax checker %S does not exist"
+             directory checker))
+    directory))
+
+;;;###autoload
+(defun flycheck-define-command-checker (symbol docstring &rest properties)
+  "Define SYMBOL as syntax checker to run a command.
+
+Define SYMBOL as generic syntax checker via
+`flycheck-define-generic-checker', which uses an external command
+to check the buffer.  SYMBOL and DOCSTRING are the same as for
+`flycheck-define-generic-checker'.
+
+In addition to the properties understood by
+`flycheck-define-generic-checker', the following PROPERTIES
+constitute a command syntax checker.  Unless otherwise noted, all
+properties are mandatory.  Note that the default `:error-filter'
+of command checkers is `flycheck-sanitize-errors'.
+
+`:command COMMAND'
+     The command to run for syntax checking.
+
+     COMMAND is a list of the form `(EXECUTABLE [ARG ...])'.
+
+     EXECUTABLE is a string with the executable of this syntax
+     checker.  It can be overridden with the variable
+     `flycheck-SYMBOL-executable'.  Note that this variable is
+     NOT implicitly defined by this function.  Use
+     `flycheck-def-executable-var' to define this variable.
+
+     Each ARG is an argument to the executable, either as string,
+     or as special symbol or form for
+     `flycheck-substitute-argument', which see.
+
+`:error-patterns PATTERNS'
+     A list of patterns to parse the output of the `:command'.
+
+     Each ITEM in PATTERNS is a list `(LEVEL SEXP ...)', where
+     LEVEL is a Flycheck error level (see
+     `flycheck-define-error-level'), followed by one or more RX
+     `SEXP's which parse an error of that level and extract line,
+     column, file name and the message.
+
+     See `rx' for general information about RX, and
+     `flycheck-rx-to-string' for some special RX forms provided
+     by Flycheck.
+
+     All patterns are applied in the order of declaration to the
+     whole output of the syntax checker.  Output already matched
+     by a pattern will not be matched by subsequent patterns.  In
+     other words, the first pattern wins.
+
+     This property is optional.  If omitted, however, an
+     `:error-parser' is mandatory.
+
+`:error-parser FUNCTION'
+     A function to parse errors with.
+
+     The function shall accept three arguments OUTPUT CHECKER
+     BUFFER.  OUTPUT is the syntax checker output as string,
+     CHECKER the syntax checker that was used, and BUFFER a
+     buffer object representing the checked buffer.  The function
+     must return a list of `flycheck-error' objects parsed from
+     OUTPUT.
+
+     This property is optional.  If omitted, it defaults to
+     `flycheck-parse-with-patterns'.  In this case,
+     `:error-patterns' is mandatory.
+
+`:standard-input t'
+     Whether to send the buffer contents on standard input.
+
+     If this property is given and has a non-nil value, send the
+     contents of the buffer on standard input.
+
+     Defaults to nil.
+
+Note that you may not give `:start', `:interrupt', and
+`:print-doc' for a command checker.  You can give a custom
+`:verify' function, though, whose results will be appended to the
+default `:verify' function of command checkers."
+  (declare (indent 1)
+           (doc-string 2))
+  (dolist (prop '(:start :interrupt :print-doc))
+    (when (plist-get properties prop)
+      (error "%s not allowed in definition of command syntax checker %s"
+             prop symbol)))
+
+  (unless (plist-get properties :error-filter)
+    ;; Default to `flycheck-sanitize-errors' as error filter
+    (setq properties (plist-put properties :error-filter
+                                #'flycheck-sanitize-errors)))
+  (let ((verify-fn (plist-get properties :verify)))
+    (setq properties
+          (plist-put properties :verify
+                     (lambda (checker)
+                       (append (flycheck-verify-command-checker checker)
+                               (and verify-fn
+                                    (funcall verify-fn checker)))))))
+
+  (let ((command (plist-get properties :command))
+        (patterns (plist-get properties :error-patterns))
+        (parser (or (plist-get properties :error-parser)
+                    #'flycheck-parse-with-patterns))
+        (enabled (plist-get properties :enabled))
+        (standard-input (plist-get properties :standard-input)))
+    (unless command
+      (error "Missing :command in syntax checker %s" symbol))
+    (unless (stringp (car command))
+      (error "Command executable for syntax checker %s must be a string: %S"
+             symbol (car command)))
+    (dolist (arg (cdr command))
+      (unless (flycheck-command-argument-p arg)
+        (error "Invalid command argument %S in syntax checker %s" arg symbol)))
+    (when (and (eq parser 'flycheck-parse-with-patterns)
+               (not patterns))
+      (error "Missing :error-patterns in syntax checker %s" symbol))
+
+    (setq properties
+          ;; Automatically disable command checkers if the executable does not
+          ;; exist.
+          (plist-put properties :enabled
+                     (lambda ()
+                       (and (flycheck-find-checker-executable symbol)
+                            (flycheck-temp-files-writable-p symbol)
+                            (or (not enabled) (funcall enabled))))))
+
+    (apply #'flycheck-define-generic-checker symbol docstring
+           :start #'flycheck-start-command-checker
+           :interrupt #'flycheck-interrupt-command-checker
+           :print-doc #'flycheck-command-checker-print-doc
+           properties)
+
+    ;; Pre-compile all errors patterns into strings, so that we don't need to do
+    ;; that on each error parse
+    (let ((patterns (seq-map (lambda (p)
+                               (cons (flycheck-rx-to-string `(and ,@(cdr p))
+                                                            'no-group)
+                                     (car p)))
+                             patterns)))
+      (pcase-dolist (`(,prop . ,value)
+                     `((command        . ,command)
+                       (error-parser   . ,parser)
+                       (error-patterns . ,patterns)
+                       (standard-input . ,standard-input)))
+        (setf (flycheck-checker-get symbol prop) value)))))
+
+(eval-and-compile
+  ;; Make this function available during byte-compilation, since we need it
+  ;; at macro expansion of `flycheck-def-executable-var'.
+  (defun flycheck-checker-executable-variable (checker)
+    "Get the executable variable of CHECKER.
+
+The executable variable is named `flycheck-CHECKER-executable'."
+    (intern (format "flycheck-%s-executable" checker))))
+
+(defun flycheck-checker-default-executable (checker)
+  "Get the default executable of CHECKER."
+  (car (flycheck-checker-get checker 'command)))
+
+(defun flycheck-checker-executable (checker)
+  "Get the command executable of CHECKER.
+
+The executable is either the value of the variable
+`flycheck-CHECKER-executable', or the default executable given in
+the syntax checker definition, if the variable is nil."
+  (let ((var (flycheck-checker-executable-variable checker)))
+    (or (and (boundp var) (symbol-value var))
+        (flycheck-checker-default-executable checker))))
+
+(defun flycheck-find-checker-executable (checker)
+  "Get the full path of the executable of CHECKER.
+
+Return the full absolute path to the executable of CHECKER, or
+nil if the executable does not exist."
+  (funcall flycheck-executable-find (flycheck-checker-executable checker)))
+
+(defun flycheck-checker-arguments (checker)
+  "Get the command arguments of CHECKER."
+  (cdr (flycheck-checker-get checker 'command)))
+
+(defun flycheck-substitute-argument (arg checker)
+  "Substitute ARG for CHECKER.
+
+Return a list of real arguments for the executable of CHECKER,
+substituted for the symbolic argument ARG.  Single arguments,
+e.g. if ARG is a literal strings, are wrapped in a list.
+
+ARG may be one of the following forms:
+
+STRING
+     Return ARG unchanged.
+
+`source', `source-inplace'
+     Create a temporary file to check and return its path.  With
+     `source-inplace' create the temporary file in the same
+     directory as the original file.  The value of
+     `flycheck-temp-prefix' is used as prefix of the file name.
+
+     With `source', try to retain the non-directory component of
+     the buffer's file name in the temporary file.
+
+     `source' is the preferred way to pass the input file to a
+     syntax checker.  `source-inplace' should only be used if the
+     syntax checker needs other files from the source directory,
+     such as include files in C.
+
+`source-original'
+     Return the path of the actual file to check, or an empty
+     string if the buffer has no file name.
+
+     Note that the contents of the file may not be up to date
+     with the contents of the buffer to check.  Do not use this
+     as primary input to a checker, unless absolutely necessary.
+
+     When using this symbol as primary input to the syntax
+     checker, add `flycheck-buffer-saved-p' to the `:predicate'.
+
+`temporary-directory'
+     Create a unique temporary directory and return its path.
+
+`temporary-file-name'
+     Return a unique temporary filename.  The file is *not*
+     created.
+
+     To ignore the output of syntax checkers, try `null-device'
+     first.
+
+`null-device'
+     Return the value of `null-device', i.e the system null
+     device.
+
+     Use this option to ignore the output of a syntax checker.
+     If the syntax checker cannot handle the null device, or
+     won't write to an existing file, try `temporary-file-name'
+     instead.
+
+`(config-file OPTION VARIABLE [PREPEND-FN])'
+     Search the configuration file bound to VARIABLE with
+     `flycheck-locate-config-file' and return a list of arguments
+     that pass this configuration file to the syntax checker, or
+     nil if the configuration file was not found.
+
+     PREPEND-FN is called with the OPTION and the located
+     configuration file, and should return OPTION prepended
+     before the file, either a string or as list.  If omitted,
+     PREPEND-FN defaults to `list'.
+
+`(option OPTION VARIABLE [PREPEND-FN [FILTER]])'
+     Retrieve the value of VARIABLE and return a list of
+     arguments that pass this value as value for OPTION to the
+     syntax checker.
+
+     PREPEND-FN is called with the OPTION and the value of
+     VARIABLE, and should return OPTION prepended before the
+     file, either a string or as list.  If omitted, PREPEND-FN
+     defaults to `list'.
+
+     FILTER is an optional function to be applied to the value of
+     VARIABLE before prepending.  This function must return nil
+     or a string.  In the former case, return nil.  In the latter
+     case, return a list of arguments as described above.
+
+`(option-list OPTION VARIABLE [PREPEND-FN [FILTER]])'
+     Retrieve the value of VARIABLE, which must be a list,
+     and prepend OPTION before each item in this list, using
+     PREPEND-FN.
+
+     PREPEND-FN is called with the OPTION and each item of the
+     list as second argument, and should return OPTION prepended
+     before the item, either as string or as list.  If omitted,
+     PREPEND-FN defaults to `list'.
+
+     FILTER is an optional function to be applied to each item in
+     the list before prepending OPTION.  It shall return the
+     option value for each item as string, or nil, if the item is
+     to be ignored.
+
+`(option-flag OPTION VARIABLE)'
+     Retrieve the value of VARIABLE and return OPTION, if the
+     value is non-nil.  Otherwise return nil.
+
+`(eval FORM)'
+     Return the result of evaluating FORM in the buffer to be
+     checked.  FORM must either return a string or a list of
+     strings, or nil to indicate that nothing should be
+     substituted for CELL.  For all other return types, signal an
+     error
+
+     _No_ further substitutions are performed, neither in FORM
+     before it is evaluated, nor in the result of evaluating
+     FORM.
+
+In all other cases, signal an error.
+
+Note that substitution is *not* recursive.  No symbols or cells
+are substituted within the body of cells!"
+  (pcase arg
+    ((pred stringp) (list arg))
+    (`source
+     (list (flycheck-save-buffer-to-temp #'flycheck-temp-file-system)))
+    (`source-inplace
+     (list (flycheck-save-buffer-to-temp #'flycheck-temp-file-inplace)))
+    (`source-original (list (or (buffer-file-name) "")))
+    (`temporary-directory (list (flycheck-temp-dir-system)))
+    (`temporary-file-name
+     (let ((directory (flycheck-temp-dir-system)))
+       (list (make-temp-name (expand-file-name "flycheck" directory)))))
+    (`null-device (list null-device))
+    (`(config-file ,option-name ,file-name-var)
+     (-when-let* ((value (symbol-value file-name-var))
+                  (file-name (flycheck-locate-config-file value checker)))
+       (flycheck-prepend-with-option option-name (list file-name))))
+    (`(config-file ,option-name ,file-name-var ,prepend-fn)
+     (-when-let* ((value (symbol-value file-name-var))
+                  (file-name (flycheck-locate-config-file value checker)))
+       (flycheck-prepend-with-option option-name (list file-name) prepend-fn)))
+    (`(option ,option-name ,variable)
+     (-when-let (value (symbol-value variable))
+       (unless (stringp value)
+         (error "Value %S of %S for option %s is not a string"
+                value variable option-name))
+       (flycheck-prepend-with-option option-name (list value))))
+    (`(option ,option-name ,variable ,prepend-fn)
+     (-when-let (value (symbol-value variable))
+       (unless (stringp value)
+         (error "Value %S of %S for option %s is not a string"
+                value variable option-name))
+       (flycheck-prepend-with-option option-name (list value) prepend-fn)))
+    (`(option ,option-name ,variable ,prepend-fn ,filter)
+     (-when-let (value (funcall filter (symbol-value variable)))
+       (unless (stringp value)
+         (error "Value %S of %S (filter: %S) for option %s is not a string"
+                value variable filter option-name))
+       (flycheck-prepend-with-option option-name (list value) prepend-fn)))
+    (`(option-list ,option-name ,variable)
+     (let ((value (symbol-value variable)))
+       (unless (and (listp value) (seq-every-p #'stringp value))
+         (error "Value %S of %S for option %S is not a list of strings"
+                value variable option-name))
+       (flycheck-prepend-with-option option-name value)))
+    (`(option-list ,option-name ,variable ,prepend-fn)
+     (let ((value (symbol-value variable)))
+       (unless (and (listp value) (seq-every-p #'stringp value))
+         (error "Value %S of %S for option %S is not a list of strings"
+                value variable option-name))
+       (flycheck-prepend-with-option option-name value prepend-fn)))
+    (`(option-list ,option-name ,variable ,prepend-fn ,filter)
+     (let ((value (delq nil (seq-map filter (symbol-value variable)))))
+       (unless (and (listp value) (seq-every-p #'stringp value))
+         (error "Value %S of %S for option %S is not a list of strings"
+                value variable option-name))
+       (flycheck-prepend-with-option option-name value prepend-fn)))
+    (`(option-flag ,option-name ,variable)
+     (when (symbol-value variable)
+       (list option-name)))
+    (`(eval ,form)
+     (let ((result (eval form)))
+       (cond
+        ((and (listp result) (seq-every-p #'stringp result)) result)
+        ((stringp result) (list result))
+        (t (error "Invalid result from evaluation of %S: %S" form result)))))
+    (_ (error "Unsupported argument %S" arg))))
+
+(defun flycheck-checker-substituted-arguments (checker)
+  "Get the substituted arguments of a CHECKER.
+
+Substitute each argument of CHECKER using
+`flycheck-substitute-argument'.  This replaces any special
+symbols in the command."
+  (apply #'append
+         (seq-map (lambda (arg) (flycheck-substitute-argument arg checker))
+                  (flycheck-checker-arguments checker))))
+
+(defun flycheck--process-send-buffer-contents-chunked (process)
+  "Send contents of current buffer to PROCESS in small batches.
+
+Send the entire buffer to the standard input of PROCESS in chunks
+of 4096 characters.  Chunking is done in Emacs Lisp, hence this
+function is probably far less efficient than
+`send-process-region'.  Use only when required."
+  (let ((from (point-min)))
+    (while (< from (point-max))
+      (let ((to (min (+ from 4096) (point-max))))
+        (process-send-region process from to)
+        (setq from to)))))
+
+(defvar flycheck-chunked-process-input
+  ;; Chunk process output on Windows to work around
+  ;; https://github.com/flycheck/flycheck/issues/794 and
+  ;; https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22344.  The presence of
+  ;; `w32-pipe-buffer-size' denotes an Emacs version (> Emacs 25.1 )where pipe
+  ;; writes on Windows are fixed.
+  ;;
+  ;; TODO: Remove option and chunking when dropping Emacs 24 support, see
+  ;; https://github.com/flycheck/flycheck/issues/856
+  (and (eq system-type 'windows-nt) (not (boundp 'w32-pipe-buffer-size)))
+  "If non-nil send process input in small chunks.
+
+If this variable is non-nil `flycheck-process-send-buffer' sends
+buffer contents in small chunks.
+
+Defaults to nil, except on Windows to work around Emacs bug
+#22344.")
+
+(defun flycheck-process-send-buffer (process)
+  "Send all contents of current buffer to PROCESS.
+
+Sends all contents of the current buffer to the standard input of
+PROCESS, and terminates standard input with EOF.
+
+If `flycheck-chunked-process-input' is non-nil, send buffer
+contents in chunks via
+`flycheck--process-send-buffer-contents-chunked', which see.
+Otherwise use `process-send-region' to send all contents at once
+and rely on Emacs' own buffering and chunking."
+  (save-restriction
+    (widen)
+    (if flycheck-chunked-process-input
+        (flycheck--process-send-buffer-contents-chunked process)
+      (process-send-region process (point-min) (point-max))))
+  (process-send-eof process))
+
+(defun flycheck-start-command-checker (checker callback)
+  "Start a command CHECKER with CALLBACK."
+  (let (process)
+    (condition-case err
+        (let* ((program (flycheck-find-checker-executable checker))
+               (args (flycheck-checker-substituted-arguments checker))
+               (command (funcall flycheck-command-wrapper-function
+                                 (cons program args)))
+               ;; Use pipes to receive output from the syntax checker.  They are
+               ;; more efficient and more robust than PTYs, which Emacs uses by
+               ;; default, and since we don't need any job control features, we
+               ;; can easily use pipes.
+               (process-connection-type nil))
+          ;; We pass do not associate the process with any buffer, by
+          ;; passing nil for the BUFFER argument of `start-process'.
+          ;; Instead, we just remember the buffer being checked in a
+          ;; process property (see below).  This neatly avoids all
+          ;; side-effects implied by attached a process to a buffer, which
+          ;; may cause conflicts with other packages.
+          ;;
+          ;; See https://github.com/flycheck/flycheck/issues/298 for an
+          ;; example for such a conflict.
+          (setq process (apply 'start-process (format "flycheck-%s" checker)
+                               nil command))
+          (setf (process-sentinel process) #'flycheck-handle-signal)
+          (setf (process-filter process) #'flycheck-receive-checker-output)
+          (set-process-query-on-exit-flag process nil)
+          ;; Remember the syntax checker, the buffer and the callback
+          (process-put process 'flycheck-checker checker)
+          (process-put process 'flycheck-callback callback)
+          (process-put process 'flycheck-buffer (current-buffer))
+          ;; The default directory is bound in the `flycheck-syntax-check-start'
+          ;; function.
+          (process-put process 'flycheck-working-directory default-directory)
+          ;; Track the temporaries created by argument substitution in the
+          ;; process itself, to get rid of the global state ASAP.
+          (process-put process 'flycheck-temporaries flycheck-temporaries)
+          (setq flycheck-temporaries nil)
+          ;; Send the buffer to the process on standard input, if enabled.
+          (when (flycheck-checker-get checker 'standard-input)
+            (flycheck-process-send-buffer process))
+          ;; Return the process.
+          process)
+      (error
+       ;; In case of error, clean up our resources, and report the error back to
+       ;; Flycheck.
+       (flycheck-safe-delete-temporaries)
+       (when process
+         ;; No need to explicitly delete the temporary files of the process,
+         ;; because deleting runs the sentinel, which will delete them anyway.
+         (delete-process process))
+       (signal (car err) (cdr err))))))
+
+(defun flycheck-interrupt-command-checker (_checker process)
+  "Interrupt a PROCESS."
+  ;; Deleting the process always triggers the sentinel, which does the cleanup
+  (when process
+    (delete-process process)))
+
+(defun flycheck-command-checker-print-doc (checker)
+  "Print additional documentation for a command CHECKER."
+  (let ((executable (flycheck-checker-default-executable checker))
+        (config-file-var (flycheck-checker-get checker 'config-file-var))
+        (option-vars (seq-sort #'string<
+                               (flycheck-checker-get checker 'option-vars))))
+    (princ "\n")
+
+    (let ((doc-start (with-current-buffer standard-output (point-max))))
+      ;; Track the start of our documentation so that we can re-indent it
+      ;; properly
+      (princ "  This syntax checker executes \"")
+      (princ executable)
+      (princ "\"")
+      (when config-file-var
+        (princ ", using a configuration file from `")
+        (princ (symbol-name config-file-var))
+        (princ "'"))
+      (princ ". The executable can be overridden with `")
+      (princ (symbol-name (flycheck-checker-executable-variable checker)))
+      (princ "'.")
+
+      (with-current-buffer standard-output
+        (save-excursion
+          (fill-region-as-paragraph doc-start (point-max)))))
+    (princ "\n")
+    (when option-vars
+      (princ
+       "\n  This syntax checker can be configured with these options:\n\n")
+      (dolist (var option-vars)
+        (princ (format "     * `%s'\n" var))))))
+
+(defun flycheck-verify-command-checker (checker)
+  "Verify a command CHECKER in the current buffer.
+
+Return a list of `flycheck-verification-result' objects for
+CHECKER."
+  (let ((executable (flycheck-find-checker-executable checker))
+        (config-file-var (flycheck-checker-get checker 'config-file-var)))
+    `(
+      ,(flycheck-verification-result-new
+        :label "executable"
+        :message (if executable (format "Found at %s" executable) "Not found")
+        :face (if executable 'success '(bold error)))
+      ,@(when config-file-var
+          (let* ((value (symbol-value config-file-var))
+                 (path (and value (flycheck-locate-config-file value checker))))
+            (list (flycheck-verification-result-new
+                   :label "configuration file"
+                   :message (if path (format "Found at %S" path) "Not found")
+                   :face (if path 'success 'warning)))))
+      ,@(when (not (flycheck-temp-files-writable-p checker))
+          (list (flycheck-verification-result-new
+                 :label "temp directory"
+                 :message (format "%s is not writable"
+                                  (flycheck-temp-directory checker))
+                 :face 'error))))))
+
+
+;;; Process management for command syntax checkers
+(defun flycheck-receive-checker-output (process output)
+  "Receive a syntax checking PROCESS OUTPUT."
+  (push output (process-get process 'flycheck-pending-output)))
+
+(defun flycheck-get-output (process)
+  "Get the complete output of PROCESS."
+  (with-demoted-errors "Error while retrieving process output: %S"
+    (let ((pending-output (process-get process 'flycheck-pending-output)))
+      (apply #'concat (nreverse pending-output)))))
+
+(defun flycheck-handle-signal (process _event)
+  "Handle a signal from the syntax checking PROCESS.
+
+_EVENT is ignored."
+  (when (memq (process-status process) '(signal exit))
+    (let ((files (process-get process 'flycheck-temporaries))
+          (buffer (process-get process 'flycheck-buffer))
+          (callback (process-get process 'flycheck-callback))
+          (cwd (process-get process 'flycheck-working-directory)))
+      ;; Delete the temporary files
+      (seq-do #'flycheck-safe-delete files)
+      (when (buffer-live-p buffer)
+        (with-current-buffer buffer
+          (condition-case err
+              (pcase (process-status process)
+                (`signal
+                 (funcall callback 'interrupted))
+                (`exit
+                 (flycheck-finish-checker-process
+                  (process-get process 'flycheck-checker)
+                  (process-exit-status process)
+                  files
+                  (flycheck-get-output process) callback cwd)))
+            ((debug error)
+             (funcall callback 'errored (error-message-string err)))))))))
+
+(defun flycheck-finish-checker-process
+    (checker exit-status files output callback cwd)
+  "Finish a checker process from CHECKER with EXIT-STATUS.
+
+FILES is a list of files given as input to the checker.  OUTPUT
+is the output of the syntax checker.  CALLBACK is the status
+callback to use for reporting.
+
+Parse the OUTPUT and report an appropriate error status.
+
+Resolve all errors in OUTPUT using CWD as working directory."
+  (let ((errors (flycheck-parse-output output checker (current-buffer))))
+    (when (and (/= exit-status 0) (not errors))
+      ;; Warn about a suspicious result from the syntax checker.  We do right
+      ;; after parsing the errors, before filtering, because a syntax checker
+      ;; might report errors from other files (e.g. includes) even if there
+      ;; are no errors in the file being checked.
+      (funcall callback 'suspicious
+               (format "Flycheck checker %S returned non-zero \
+exit code %s, but its output contained no errors: %s\nTry \
+installing a more recent version of %S, and please open a bug \
+report if the issue persists in the latest release.  Thanks!"
+                       checker exit-status output checker)))
+    (funcall callback 'finished
+             ;; Fix error file names, by substituting them backwards from the
+             ;; temporaries.
+             (seq-map (lambda (e) (flycheck-fix-error-filename e files cwd))
+                      errors))))
+
+
+;;; Executables of command checkers.
+(defmacro flycheck-def-executable-var (checker default-executable)
+  "Define the executable variable for CHECKER.
+
+DEFAULT-EXECUTABLE is the default executable.  It is only used in
+the docstring of the variable.
+
+The variable is defined with `defcustom' in the
+`flycheck-executables' group.  It's also defined to be risky as
+file-local variable, to avoid arbitrary executables being used
+for syntax checking."
+  (let ((executable-var (flycheck-checker-executable-variable checker)))
+    `(progn
+       (defcustom ,executable-var nil
+         ,(format "The executable of the %s syntax checker.
+
+Either a string containing the name or the path of the
+executable, or nil to use the default executable from the syntax
+checker declaration.
+
+The default executable is %S." checker default-executable)
+         :type '(choice (const :tag "Default executable" nil)
+                        (string :tag "Name or path"))
+         :group 'flycheck-executables
+         :risky t))))
+
+(defun flycheck-set-checker-executable (checker &optional executable)
+  "Set the executable of CHECKER in the current buffer.
+
+CHECKER is a syntax checker symbol.  EXECUTABLE is a string with
+the name of an executable or the path to an executable file, which
+is to be used as executable for CHECKER.  If omitted or nil,
+reset the executable of CHECKER.
+
+Interactively, prompt for a syntax checker and an executable
+file, and set the executable of the selected syntax checker.
+With prefix arg, prompt for a syntax checker only, and reset the
+executable of the select checker to the default.
+
+Set the executable variable of CHECKER, that is,
+`flycheck-CHECKER-executable' to EXECUTABLE.  Signal
+`user-error', if EXECUTABLE does not denote a command or an
+executable file.
+
+This command is intended for interactive use only.  In Lisp, just
+`let'-bind the corresponding variable, or set it directly.  Use
+`flycheck-checker-executable-variable' to obtain the executable
+variable symbol for a syntax checker."
+  (declare (interactive-only "Set the executable variable directly instead"))
+  (interactive
+   (let* ((checker (read-flycheck-checker "Syntax checker: "))
+          (default-executable (flycheck-checker-default-executable checker))
+          (executable (if current-prefix-arg
+                          nil
+                        (read-file-name "Executable: " nil default-executable
+                                        nil nil flycheck-executable-find))))
+     (list checker executable)))
+  (when (and executable (not (funcall flycheck-executable-find executable)))
+    (user-error "%s is no executable" executable))
+  (let ((variable (flycheck-checker-executable-variable checker)))
+    (set (make-local-variable variable) executable)))
+
+
+;;; Configuration files and options for command checkers
+(defun flycheck-register-config-file-var (var checkers)
+  "Register VAR as config file var for CHECKERS.
+
+CHECKERS is a single syntax checker or a list thereof."
+  (when (symbolp checkers)
+    (setq checkers (list checkers)))
+  (dolist (checker checkers)
+    (setf (flycheck-checker-get checker 'config-file-var) var)))
+
+;;;###autoload
+(defmacro flycheck-def-config-file-var (symbol checker &optional file-name
+                                               &rest custom-args)
+  "Define SYMBOL as config file variable for CHECKER, with default FILE-NAME.
+
+SYMBOL is declared as customizable variable using `defcustom', to
+provide a configuration file for the given syntax CHECKER.
+CUSTOM-ARGS are forwarded to `defcustom'.
+
+FILE-NAME is the initial value of the new variable.  If omitted,
+the default value is nil.
+
+Use this together with the `config-file' form in the `:command'
+argument to `flycheck-define-checker'."
+  ;; FIXME: We should allow multiple config files per checker as well as
+  ;; multiple checkers per config file
+  (declare (indent 3))
+  `(progn
+     (defcustom ,symbol ,file-name
+       ,(format "Configuration file for `%s'.
+
+If set to a string, locate the configuration file using the
+functions from `flycheck-locate-config-file-functions'.  If the
+file is found pass it to the syntax checker as configuration
+file.
+
+If no configuration file is found, or if this variable is set to
+nil, invoke the syntax checker without a configuration file.
+
+Use this variable as file-local variable if you need a specific
+configuration file a buffer." checker)
+       :type '(choice (const :tag "No configuration file" nil)
+                      (string :tag "File name or path"))
+       :group 'flycheck-config-files
+       ,@custom-args)
+     (flycheck-register-config-file-var ',symbol ',checker)))
+
+(defun flycheck-locate-config-file (filename checker)
+  "Locate the configuration file FILENAME for CHECKER.
+
+Locate the configuration file using
+`flycheck-locate-config-file-functions'.
+
+Return the absolute path of the configuration file, or nil if no
+configuration file was found."
+  (-when-let (filepath (run-hook-with-args-until-success
+                        'flycheck-locate-config-file-functions
+                        filename checker))
+    (when (file-exists-p filepath)
+      filepath)))
+
+(defun flycheck-locate-config-file-by-path (filepath _checker)
+  "Locate a configuration file by a FILEPATH.
+
+If FILEPATH is a contains a path separator, expand it against the
+default directory and return it if it points to an existing file.
+Otherwise return nil.
+
+_CHECKER is ignored."
+  ;; If the path is just a plain file name, skip it.
+  (unless (string= (file-name-nondirectory filepath) filepath)
+    (let ((file-name (expand-file-name filepath)))
+      (and (file-exists-p file-name) file-name))))
+
+(defun flycheck-locate-config-file-ancestor-directories (filename _checker)
+  "Locate a configuration FILENAME in ancestor directories.
+
+If the current buffer has a file name, search FILENAME in the
+directory of the current buffer and all ancestors thereof (see
+`locate-dominating-file').  If the file is found, return its
+absolute path.  Otherwise return nil.
+
+_CHECKER is ignored."
+  (-when-let* ((basefile (buffer-file-name))
+               (directory (locate-dominating-file basefile filename)))
+    (expand-file-name filename directory)))
+
+(defun flycheck-locate-config-file-home (filename _checker)
+  "Locate a configuration FILENAME in the home directory.
+
+Return the absolute path, if FILENAME exists in the user's home
+directory, or nil otherwise."
+  (let ((path (expand-file-name filename "~")))
+    (when (file-exists-p path)
+      path)))
+
+(seq-do (apply-partially #'custom-add-frequent-value
+                         'flycheck-locate-config-file-functions)
+        '(flycheck-locate-config-file-by-path
+          flycheck-locate-config-file-ancestor-directories
+          flycheck-locate-config-file-home))
+
+(defun flycheck-register-option-var (var checkers)
+  "Register an option VAR with CHECKERS.
+
+VAR is an option symbol, and CHECKERS a syntax checker symbol or
+a list thereof.  Register VAR with all CHECKERS so that it
+appears in the help output."
+  (when (symbolp checkers)
+    (setq checkers (list checkers)))
+  (dolist (checker checkers)
+    (cl-pushnew var (flycheck-checker-get checker 'option-vars))))
+
+;;;###autoload
+(defmacro flycheck-def-option-var (symbol init-value checkers docstring
+                                          &rest custom-args)
+  "Define SYMBOL as option variable with INIT-VALUE for CHECKER.
+
+SYMBOL is declared as customizable variable using `defcustom', to
+provide an option for the given syntax CHECKERS (a checker or a
+list of checkers).  INIT-VALUE is the initial value of the
+variable, and DOCSTRING is its docstring.  CUSTOM-ARGS are
+forwarded to `defcustom'.
+
+Use this together with the `option', `option-list' and
+`option-flag' forms in the `:command' argument to
+`flycheck-define-checker'."
+  (declare (indent 3)
+           (doc-string 4))
+  `(progn
+     (defcustom ,symbol ,init-value
+       ,(concat docstring "
+
+This variable is an option for the following syntax checkers:
+
+"
+                (mapconcat (lambda (c) (format "  - `%s'" c))
+                           (if (symbolp checkers) (list checkers) checkers)
+                           "\n"))
+       :group 'flycheck-options
+       ,@custom-args)
+     (flycheck-register-option-var ',symbol ',checkers)))
+
+(defun flycheck-option-int (value)
+  "Convert an integral option VALUE to a string.
+
+If VALUE is nil, return nil.  Otherwise return VALUE converted to
+a string."
+  (and value (number-to-string value)))
+
+(defun flycheck-option-symbol (value)
+  "Convert a symbol option VALUE to string.
+
+If VALUE is nil return nil.  Otherwise return VALUE converted to
+a string."
+  (and value (symbol-name value)))
+
+(defun flycheck-option-comma-separated-list (value &optional separator filter)
+  "Convert VALUE into a list separated by SEPARATOR.
+
+SEPARATOR is a string to separate items in VALUE, defaulting to
+\",\".  FILTER is an optional function, which takes a single
+argument and returns either a string or nil.
+
+If VALUE is a list, apply FILTER to each item in VALUE, remove
+all nil items, and return a single string of all remaining items
+separated by SEPARATOR.
+
+Otherwise, apply FILTER to VALUE and return the result.
+SEPARATOR is ignored in this case."
+  (let ((filter (or filter #'identity))
+        (separator (or separator ",")))
+    (if (listp value)
+        (-when-let (value (delq nil (seq-map filter value)))
+          (string-join value separator))
+      (funcall filter value))))
+
+(defmacro flycheck-def-args-var (symbol checkers &rest custom-args)
+  "Define SYMBOL as argument variable for CHECKERS.
+
+SYMBOL is declared as customizable, risky and buffer-local
+variable using `defcustom' to provide an option for arbitrary
+arguments for the given syntax CHECKERS (either a single checker
+or a list of checkers).  CUSTOM-ARGS is forwarded to `defcustom'.
+
+Use the `eval' form to splice this variable into the
+`:command'."
+  (declare (indent 2))
+  `(flycheck-def-option-var ,symbol nil ,checkers
+     "A list of additional command line arguments.
+
+The value of this variable is a list of strings with additional
+command line arguments."
+     :risky t
+     :type '(repeat (string :tag "Argument"))
+     ,@custom-args))
+
+
+;;; Command syntax checkers as compile commands
+(defun flycheck-checker-pattern-to-error-regexp (pattern)
+  "Convert PATTERN into an error regexp for compile.el.
+
+Return a list representing PATTERN, suitable as element in
+`compilation-error-regexp-alist'."
+  (let* ((regexp (car pattern))
+         (level (cdr pattern))
+         (level-no (flycheck-error-level-compilation-level level)))
+    (list regexp 1 2 3 level-no)))
+
+(defun flycheck-checker-compilation-error-regexp-alist (checker)
+  "Convert error patterns of CHECKER for use with compile.el.
+
+Return an alist of all error patterns of CHECKER, suitable for
+use with `compilation-error-regexp-alist'."
+  (seq-map #'flycheck-checker-pattern-to-error-regexp
+           (flycheck-checker-get checker 'error-patterns)))
+
+(defun flycheck-checker-shell-command (checker)
+  "Get a shell command for CHECKER.
+
+Perform substitution in the arguments of CHECKER, but with
+`flycheck-substitute-shell-argument'.
+
+Return the command of CHECKER as single string, suitable for
+shell execution."
+  ;; Note: Do NOT use `combine-and-quote-strings' here.  Despite it's name it
+  ;; does not properly quote shell arguments, and actually breaks for special
+  ;; characters.  See https://github.com/flycheck/flycheck/pull/522
+  (let* ((args (apply #'append
+                      (seq-map
+                       (lambda (arg)
+                         (if (memq arg '(source source-inplace source-original))
+                             (list (buffer-file-name))
+                           (flycheck-substitute-argument arg checker)))
+                       (flycheck-checker-arguments checker))))
+         (command (mapconcat
+                   #'shell-quote-argument
+                   (funcall flycheck-command-wrapper-function
+                            (cons (flycheck-checker-executable checker) args))
+                   " ")))
+    (if (flycheck-checker-get checker 'standard-input)
+        ;; If the syntax checker expects the source from standard input add an
+        ;; appropriate shell redirection
+        (concat command " < " (shell-quote-argument (buffer-file-name)))
+      command)))
+
+(defun flycheck-compile-name (_name)
+  "Get a name for a Flycheck compilation buffer.
+
+_NAME is ignored."
+  (format "*Flycheck %s*" (buffer-file-name)))
+
+(defun flycheck-compile (checker)
+  "Run CHECKER via `compile'.
+
+CHECKER must be a valid syntax checker.  Interactively, prompt
+for a syntax checker to run.
+
+Instead of highlighting errors in the buffer, this command pops
+up a separate buffer with the entire output of the syntax checker
+tool, just like `compile' (\\[compile])."
+  (interactive
+   (let ((default (flycheck-get-checker-for-buffer)))
+     (list (read-flycheck-checker "Run syntax checker as compile command: "
+                                  (when (flycheck-checker-get default 'command)
+                                    default)
+                                  'command))))
+  (unless (flycheck-valid-checker-p checker)
+    (user-error "%S is not a valid syntax checker" checker))
+  (unless (buffer-file-name)
+    (user-error "Cannot compile buffers without backing file"))
+  (unless (flycheck-may-use-checker checker)
+    (user-error "Cannot use syntax checker %S in this buffer" checker))
+  (unless (flycheck-checker-executable checker)
+    (user-error "Cannot run checker %S as shell command" checker))
+  (let* ((default-directory (flycheck-compute-working-directory checker))
+         (command (flycheck-checker-shell-command checker))
+         (buffer (compilation-start command nil #'flycheck-compile-name)))
+    (with-current-buffer buffer
+      (setq-local compilation-error-regexp-alist
+                  (flycheck-checker-compilation-error-regexp-alist checker)))))
+
+
+;;; General error parsing for command checkers
+(defun flycheck-parse-output (output checker buffer)
+  "Parse OUTPUT from CHECKER in BUFFER.
+
+OUTPUT is a string with the output from the checker symbol
+CHECKER.  BUFFER is the buffer which was checked.
+
+Return the errors parsed with the error patterns of CHECKER."
+  (funcall (flycheck-checker-get checker 'error-parser) output checker buffer))
+
+(defun flycheck-fix-error-filename (err buffer-files cwd)
+  "Fix the file name of ERR from BUFFER-FILES.
+
+Resolves error file names relative to CWD directory.
+
+Make the file name of ERR absolute.  If the absolute file name of
+ERR is in BUFFER-FILES, replace it with the return value of the
+function `buffer-file-name'."
+  (flycheck-error-with-buffer err
+    (-when-let (filename (flycheck-error-filename err))
+      (when (seq-some (apply-partially #'flycheck-same-files-p
+                                       (expand-file-name filename cwd))
+                      buffer-files)
+        (setf (flycheck-error-filename err) buffer-file-name)
+        (when (and buffer-file-name (flycheck-error-message err))
+          (setf (flycheck-error-message err)
+                (replace-regexp-in-string
+                 (regexp-quote filename) buffer-file-name
+                 (flycheck-error-message err) 'fixed-case 'literal))))))
+  err)
+
+
+;;; Error parsers for command syntax checkers
+(defun flycheck-parse-xml-region (beg end)
+  "Parse the xml region between BEG and END.
+
+Wrapper around `xml-parse-region' which transforms the return
+value of this function into one compatible to
+`libxml-parse-xml-region' by simply returning the first element
+from the node list."
+  (ignore-errors (car (xml-parse-region beg end))))
+
+(defun flycheck-parse-xml-region-with-fallback (beg end)
+  "Parse the xml region between BEG and END.
+
+Try parsing with libxml first; if that fails, revert to
+`flycheck-parse-xml-region'.  Failures can be caused by incorrect
+XML (see URL `https://github.com/flycheck/flycheck/issues/1298'),
+or on Windows by a missing libxml DLL with a libxml-enabled Emacs
+\(see URL `https://github.com/flycheck/flycheck/issues/1330')."
+  ;; FIXME use `libxml-available-p' when it gets implemented.
+  (or (and (fboundp 'libxml-parse-xml-region)
+           (libxml-parse-xml-region beg end))
+      (flycheck-parse-xml-region beg end)))
+
+(defvar flycheck-xml-parser 'flycheck-parse-xml-region-with-fallback
+  "Function used to parse an xml string from a region.
+
+The default uses libxml if available, and falls back to
+`flycheck-parse-xml-region' otherwise.")
+
+(defun flycheck-parse-xml-string (xml)
+  "Parse an XML string.
+
+Return the document tree parsed from XML in the form `(ROOT ATTRS
+BODY...)'.  ROOT is a symbol identifying the name of the root
+element.  ATTRS is an alist of the attributes of the root node.
+BODY is zero or more body elements, either as strings (in case of
+text nodes) or as XML nodes, in the same for as the root node."
+  (with-temp-buffer
+    (insert xml)
+    (funcall flycheck-xml-parser (point-min) (point-max))))
+
+(defun flycheck-parse-checkstyle (output checker buffer)
+  "Parse Checkstyle errors from OUTPUT.
+
+Parse Checkstyle-like XML output.  Use this error parser for
+checkers that have an option to output errors in this format.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `http://checkstyle.sourceforge.net/' for information
+about Checkstyle."
+  (pcase (flycheck-parse-xml-string output)
+    (`(checkstyle ,_ . ,file-nodes)
+     (let (errors)
+       (dolist (node file-nodes)
+         (pcase node
+           (`(file ,file-attrs . ,error-nodes)
+            (dolist (node error-nodes)
+              (pcase node
+                (`(error ,error-attrs . ,_)
+                 (let-alist error-attrs
+                   (push (flycheck-error-new-at
+                          (flycheck-string-to-number-safe .line)
+                          (flycheck-string-to-number-safe .column)
+                          (pcase .severity
+                            (`"error"   'error)
+                            (`"warning" 'warning)
+                            (`"info"    'info)
+                            ;; Default to error for unknown .severity
+                            (_          'error))
+                          .message
+                          :checker checker :id .source
+                          :buffer buffer
+                          :filename (cdr (assq 'name file-attrs)))
+                         errors))))))))
+       (nreverse errors)))))
+
+(defun flycheck-parse-cppcheck (output checker buffer)
+  "Parse Cppcheck errors from OUTPUT.
+
+Parse Cppcheck XML v2 output.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `http://cppcheck.sourceforge.net/' for more information
+about Cppcheck."
+  (pcase (flycheck-parse-xml-string output)
+    (`(results ,_ . ,body)
+     (let (errors)
+       (dolist (node body)
+         (pcase node
+           (`(errors ,_ . ,error-nodes)
+            (dolist (node error-nodes)
+              (pcase node
+                (`(error ,error-attrs . ,loc-nodes)
+                 (let ((id (cdr (assq 'id error-attrs)))
+                       (message (cdr (assq 'verbose error-attrs)))
+                       (level (pcase (cdr (assq 'severity error-attrs))
+                                (`"error" 'error)
+                                (`"style" 'info)
+                                (`"information" 'info)
+                                (_ 'warning))))
+                   (dolist (node loc-nodes)
+                     (pcase node
+                       (`(location ,loc-attrs . ,_)
+                        (let-alist loc-attrs
+                          (push (flycheck-error-new-at
+                                 (flycheck-string-to-number-safe .line)
+                                 nil
+                                 level
+                                 ;; cppcheck return newline characters as "\012"
+                                 (replace-regexp-in-string "\\\\012" "\n"
+                                                           message)
+                                 :id id
+                                 :checker checker
+                                 :buffer buffer
+                                 :filename .file)
+                                errors))))))))))))
+       (nreverse errors)))))
+
+(defun flycheck-parse-phpmd (output checker buffer)
+  "Parse phpmd errors from OUTPUT.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `http://phpmd.org/' for more information about phpmd."
+  (pcase (flycheck-parse-xml-string output)
+    (`(pmd ,_ . ,body)
+     (let (errors)
+       (dolist (node body)
+         (pcase node
+           (`(file ,file-attrs . ,violation-nodes)
+            (let ((filename (cdr (assq 'name file-attrs))))
+              (dolist (node violation-nodes)
+                (pcase node
+                  (`(violation ,vio-attrs ,(and message (pred stringp)))
+                   (let-alist vio-attrs
+                     (push
+                      (flycheck-error-new-at
+                       (flycheck-string-to-number-safe .beginline)
+                       nil
+                       'warning (string-trim message)
+                       :id .rule
+                       :checker checker
+                       :buffer buffer
+                       :filename filename)
+                      errors)))))))))
+       (nreverse errors)))))
+
+(defun flycheck-parse-reek (output checker buffer)
+  "Parse Reek warnings from JSON OUTPUT.
+
+CHECKER and BUFFER denote the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `https://github.com/troessner/reek' for more information
+about Reek."
+  (let ((errors nil))
+    (dolist (message (car (flycheck-parse-json output)))
+      (let-alist message
+        (dolist (line (delete-dups .lines))
+          (push
+           (flycheck-error-new-at
+            line
+            nil
+            'warning (concat .context " " .message)
+            :id .smell_type
+            :checker checker
+            :buffer buffer
+            :filename .source)
+           errors))))
+    (nreverse errors)))
+
+(defun flycheck-parse-tslint (output checker buffer)
+  "Parse TSLint errors from JSON OUTPUT.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `https://palantir.github.io/tslint/' for more information
+about TSLint."
+  (let ((json-array-type 'list))
+    (seq-map (lambda (message)
+               (let-alist message
+                 (flycheck-error-new-at
+                  (+ 1 .startPosition.line)
+                  (+ 1 .startPosition.character)
+                  'warning .failure
+                  :id .ruleName
+                  :checker checker
+                  :buffer buffer
+                  :filename .name)))
+             ;; Don't try to parse empty output as JSON
+             (and (not (string-empty-p output))
+                  (car (flycheck-parse-json output))))))
+
+(defun flycheck-parse-rust-collect-spans (span)
+  "Return a list of spans contained in a SPAN object."
+  (let ((spans))
+    (let-alist span
+      ;; With macro expansion errors, some spans will point to phony file names
+      ;; to indicate an error inside the std rust lib.  We skip these spans as
+      ;; they won't appear in flycheck anyway.
+      (unless (string= .file_name "<std macros>")
+        (push span spans))
+
+      ;; Macro expansion errors will have a span in the 'expansion' field, so we
+      ;; recursively collect it.
+      (if .expansion.span
+          (append (flycheck-parse-rust-collect-spans .expansion.span)
+                  spans)
+        spans))))
+
+(defun flycheck-parse-rustc-diagnostic (diagnostic checker buffer)
+  "Turn a rustc DIAGNOSTIC into a `flycheck-error'.
+
+CHECKER and BUFFER denote the CHECKER that returned DIAGNOSTIC
+and the BUFFER that was checked respectively.
+
+DIAGNOSTIC should be a parsed JSON object describing a rustc
+diagnostic, following the format described there:
+
+https://github.com/rust-lang/rust/blob/master/src/libsyntax/json.rs#L67-L139"
+  (let ((error-message)
+        (error-level)
+        (error-code)
+        (primary-filename)
+        (primary-line)
+        (primary-column)
+        (group (make-symbol "group"))
+        (spans)
+        (children)
+        (errors))
+    ;; The diagnostic format is described in the link above.  The gist of it is
+    ;; that a diagnostic can have several causes in the source text; these
+    ;; causes are represented by spans.  The diagnostic has a message and a
+    ;; level (error, warning), while the spans have a filename, line, column,
+    ;; and an optional label.  The primary span points to the root cause of the
+    ;; error in the source text, while non-primary spans point to related
+    ;; causes.  Spans may have an 'expansion' field for macro expansion errors;
+    ;; these expansion fields will contain another span (and so on).  In
+    ;; addition, a diagnostic can also have children diagnostics that are used
+    ;; to provide additional information through their message field, but do not
+    ;; seem to contain any spans (yet).
+    ;;
+    ;; We first gather spans in order to turn every span into a flycheck error
+    ;; object, that we collect into the `errors' list.
+
+    ;; Nested `let-alist' cause compilation warnings, hence we `setq' all
+    ;; these values here first to avoid nesting.
+    (let-alist diagnostic
+      (setq error-message .message
+            error-level (pcase .level
+                          (`"error" 'error)
+                          (`"warning" 'warning)
+                          (`"note" 'info)
+                          (_ 'error))
+            ;; The 'code' field of the diagnostic contains the actual error
+            ;; code and an optional explanation that we ignore
+            error-code .code.code
+            ;; Collect all spans recursively
+            spans (seq-mapcat #'flycheck-parse-rust-collect-spans .spans)
+            children .children))
+
+    ;; Turn each span into a flycheck error
+    (dolist (span spans)
+      (let-alist span
+        ;; Children may not have filename/line/column information, so we use
+        ;; those from the primary span
+        (when .is_primary
+          (setq primary-filename .file_name
+                primary-line .line_start
+                primary-column .column_start))
+        (push
+         (flycheck-error-new-at
+          .line_start
+          .column_start
+          ;; Non-primary spans are used for notes
+          (if .is_primary error-level 'info)
+          (if .is_primary
+              ;; Primary spans may have labels with additional information
+              (concat error-message (when .label
+                                      (format " (%s)" .label)))
+            ;; If the label is empty, fallback on the error message,
+            ;; otherwise we won't be able to display anything
+            (or .label error-message))
+          :id error-code
+          :checker checker
+          :buffer buffer
+          :filename .file_name
+          :group group)
+         errors)))
+
+    ;; Then we turn children messages into flycheck errors pointing to the
+    ;; location of the primary span.
+    (dolist (child children)
+      (let-alist child
+        (push
+         (flycheck-error-new-at
+          ;; Use the line/column from the first span if there is one, or
+          ;; fallback to the line/column information from the primary span of
+          ;; the diagnostic.
+          (or (cdr (assq 'line_start (car .spans)))
+              primary-line)
+          (or (cdr (assq 'column_start (car .spans)))
+              primary-column)
+          'info
+          ;; Messages from `cargo clippy' may suggest replacement code.  In
+          ;; these cases, the `message' field itself is an unhelpful `try' or
+          ;; `change this to'.  We add the `suggested_replacement' field in
+          ;; these cases.
+          (-if-let (replacement
+                    (cdr (assq 'suggested_replacement (car .spans))))
+              (format "%s: `%s`" .message replacement)
+            .message)
+          :id error-code
+          :checker checker
+          :buffer buffer
+          :filename primary-filename
+          :group group)
+         errors)))
+
+    ;; If there are no spans, the error is not associated with a specific
+    ;; file but with the project as a whole.  We still need to report it to
+    ;; the user by emitting a corresponding flycheck-error object.
+    (unless spans
+      (push (flycheck-error-new-at
+             ;; We have no specific position to attach the error to, so
+             ;; let's use the top of the file.
+             1 1
+             error-level
+             error-message
+             :id error-code
+             :checker checker
+             :buffer buffer
+             :group group)
+            errors))
+    (nreverse errors)))
+
+(defun flycheck-parse-json (output)
+  "Return parsed JSON data from OUTPUT.
+
+OUTPUT is a string that contains JSON data.  Each line of OUTPUT
+may be either plain text, a JSON array (starting with `['), or a
+JSON object (starting with `{').
+
+This function ignores the plain text lines, parses the JSON
+lines, and returns the parsed JSON lines in a list."
+  (let ((objects nil)
+        (json-array-type 'list)
+        (json-false nil))
+    (with-temp-buffer
+      (insert output)
+      (goto-char (point-min))
+      (while (not (eobp))
+        (when (memq (char-after) '(?\{ ?\[))
+          (push (json-read) objects))
+        (forward-line)))
+    (nreverse objects)))
+
+(defun flycheck-parse-rustc (output checker buffer)
+  "Parse rustc errors from OUTPUT and return a list of `flycheck-error'.
+
+CHECKER and BUFFER denote the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+The expected format for OUTPUT is a mix of plain text lines and
+JSON lines.  This function ignores the plain text lines and
+parses only JSON lines.  Each JSON line is expected to be a JSON
+object that corresponds to a diagnostic from the compiler.  The
+expected diagnostic format is described there:
+
+https://github.com/rust-lang/rust/blob/master/src/libsyntax/json.rs#L67-L139"
+  (seq-mapcat (lambda (msg)
+                (flycheck-parse-rustc-diagnostic msg checker buffer))
+              (flycheck-parse-json output)))
+
+(defun flycheck-parse-cargo-rustc (output checker buffer)
+  "Parse Cargo errors from OUTPUT and return a list of `flycheck-error'.
+
+CHECKER and BUFFER denote the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+The expected format for OUTPUT is a mix of plain text lines and
+JSON lines.  This function ignores the plain text lines and
+parses only JSON lines.  Each JSON line is expected to be a JSON
+object that represents a message from Cargo.  The format of
+messages emitted by Cargo is described in cargo's
+machine_message.rs at URL `https://git.io/vh24R'."
+  (let ((errors))
+    (dolist (msg (flycheck-parse-json output))
+      (let-alist msg
+        ;; Errors and warnings from rustc are wrapped by cargo, so we filter and
+        ;; unwrap them, and delegate the actual construction of `flycheck-error'
+        ;; objects to `flycheck-parse-rustc-diagnostic'.
+        (when (string= .reason "compiler-message")
+          (push (flycheck-parse-rustc-diagnostic .message checker buffer)
+                errors))))
+    (apply #'nconc errors)))
+
+
+;;; Error parsing with regular expressions
+(defun flycheck-get-regexp (patterns)
+  "Create a single regular expression from PATTERNS."
+  (rx-to-string `(or ,@(seq-map (lambda (p) (list 'regexp (car p))) patterns))
+                'no-group))
+
+(defun flycheck-tokenize-output-with-patterns (output patterns)
+  "Tokenize OUTPUT with PATTERNS.
+
+Split the output into error tokens, using all regular expressions
+from the error PATTERNS.  An error token is simply a string
+containing a single error from OUTPUT.  Such a token can then be
+parsed into a structured error by applying the PATTERNS again,
+see `flycheck-parse-errors-with-patterns'.
+
+Return a list of error tokens."
+  (let ((regexp (flycheck-get-regexp patterns))
+        (last-match 0)
+        errors)
+    (while (string-match regexp output last-match)
+      (push (match-string 0 output) errors)
+      (setq last-match (match-end 0)))
+    (reverse errors)))
+
+(defun flycheck-try-parse-error-with-pattern (err pattern checker)
+  "Try to parse a single ERR with a PATTERN for CHECKER.
+
+Return the parsed error if PATTERN matched ERR, or nil
+otherwise."
+  (let ((regexp (car pattern))
+        (level (cdr pattern)))
+    (when (string-match regexp err)
+      (let ((filename (match-string 1 err))
+            (line (match-string 2 err))
+            (column (match-string 3 err))
+            (message (match-string 4 err))
+            (id (match-string 5 err)))
+        (flycheck-error-new-at
+         (flycheck-string-to-number-safe line)
+         (flycheck-string-to-number-safe column)
+         level
+         (unless (string-empty-p message) message)
+         :id (unless (string-empty-p id) id)
+         :checker checker
+         :filename (if (or (null filename) (string-empty-p filename))
+                       (buffer-file-name)
+                     filename))))))
+
+(defun flycheck-parse-error-with-patterns (err patterns checker)
+  "Parse a single ERR with error PATTERNS for CHECKER.
+
+Apply each pattern in PATTERNS to ERR, in the given order, and
+return the first parsed error."
+  ;; Try to parse patterns in the order of declaration to make sure that the
+  ;; first match wins.
+  (let (parsed-error)
+    (while (and patterns
+                (not (setq parsed-error
+                           (flycheck-try-parse-error-with-pattern
+                            err (car patterns) checker))))
+      (setq patterns (cdr patterns)))
+    parsed-error))
+
+(defun flycheck-parse-with-patterns (output checker buffer)
+  "Parse OUTPUT from CHECKER with error patterns.
+
+Uses the error patterns of CHECKER to tokenize the output and
+tries to parse each error token with all patterns, in the order
+of declaration.  Hence an error is never matched twice by two
+different patterns.  The pattern declared first always wins.
+
+_BUFFER is ignored.
+
+Return a list of parsed errors and warnings (as `flycheck-error'
+objects)."
+  (with-current-buffer buffer
+    (let ((patterns (flycheck-checker-get checker 'error-patterns)))
+      (seq-map (lambda (err)
+                 (flycheck-parse-error-with-patterns err patterns checker))
+               (flycheck-tokenize-output-with-patterns output patterns)))))
+
+
+;;; Convenience definition of command-syntax checkers
+(defmacro flycheck-define-checker (symbol docstring &rest properties)
+  "Define SYMBOL as command syntax checker with DOCSTRING and PROPERTIES.
+
+Like `flycheck-define-command-checker', but PROPERTIES must not
+be quoted.  Also, implicitly define the executable variable for
+SYMBOL with `flycheck-def-executable-var'."
+  (declare (indent 1)
+           (doc-string 2))
+  (let ((command (plist-get properties :command))
+        (parser (plist-get properties :error-parser))
+        (filter (plist-get properties :error-filter))
+        (explainer (plist-get properties :error-explainer))
+        (predicate (plist-get properties :predicate))
+        (enabled-fn (plist-get properties :enabled))
+        (verify-fn (plist-get properties :verify)))
+
+    `(progn
+       (flycheck-def-executable-var ,symbol ,(car command))
+
+       (flycheck-define-command-checker ',symbol
+         ,docstring
+         :command ',command
+         ,@(when parser
+             `(:error-parser #',parser))
+         :error-patterns ',(plist-get properties :error-patterns)
+         ,@(when filter
+             `(:error-filter #',filter))
+         ,@(when explainer
+             `(:error-explainer #',explainer))
+         :modes ',(plist-get properties :modes)
+         ,@(when predicate
+             `(:predicate #',predicate))
+         :next-checkers ',(plist-get properties :next-checkers)
+         ,@(when enabled-fn
+             `(:enabled #',enabled-fn))
+         ,@(when verify-fn
+             `(:verify #',verify-fn))
+         :standard-input ',(plist-get properties :standard-input)
+         :working-directory ',(plist-get properties :working-directory)))))
+
+
+;;; Built-in checkers
+(flycheck-def-args-var flycheck-gnat-args ada-gnat
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gnat-include-path nil ada-gnat
+  "A list of include directories for GNAT.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of gcc.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gnat-language-standard "2012" ada-gnat
+  "The language standard to use in GNAT.
+
+The value of this variable is either a string denoting a language
+standard, or nil, to use the default standard. When non-nil, pass
+the language standard via the `-std' option."
+  :type '(choice (const :tag "Default standard" nil)
+                 (string :tag "Language standard"))
+  :safe #'stringp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gnat-warnings
+    '("wa") ada-gnat
+  "A list of additional Ada warnings to enable in GNAT.
+
+The value of this variable is a list of strings, where each
+string is the name of a warning category to enable. By default,
+most optional warnings are recommended, as in `-gnata'.
+
+Refer to Info Node `(gnat_ugn_unw)Warning Message Control' for
+more information about GNAT warnings."
+  :type '(repeat :tag "Warnings" (string :tag "Warning name"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-define-checker ada-gnat
+  "An Ada syntax checker using GNAT.
+
+Uses the GNAT compiler from GCC.  See URL
+`https://www.adacore.com/community/'."
+  :command ("gnatmake"
+            "-c"                        ; Just compile, don't bind
+            "-f"                        ; Force re-compilation
+            "-u"                        ; Compile the main file only
+            "-gnatf"                    ; Full error information
+            "-gnatef"                   ; Full source file name
+            "-D" temporary-directory
+            (option-list "-gnat" flycheck-gnat-warnings concat)
+            (option-list "-I" flycheck-gnat-include-path concat)
+            (option "-gnat" flycheck-gnat-language-standard concat)
+            (eval flycheck-gnat-args)
+            source)
+  :error-patterns
+  ((error line-start
+          (message "In file included from") " " (file-name) ":" line ":"
+          column ":"
+          line-end)
+   (info line-start (file-name) ":" line ":" column
+         ": note: " (message) line-end)
+   (warning line-start (file-name) ":" line ":" column
+            ": warning: " (message) line-end)
+   ;; no specific error prefix in Ada
+   (error line-start (file-name) ":" line ":" column
+          ": " (message) line-end))
+  :modes ada-mode)
+
+(flycheck-define-checker asciidoc
+  "A AsciiDoc syntax checker using the AsciiDoc compiler.
+
+See URL `http://www.methods.co.nz/asciidoc'."
+  :command ("asciidoc" "-o" null-device "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          "asciidoc: ERROR: <stdin>: Line " line ": " (message)
+          line-end)
+   (warning line-start
+            "asciidoc: WARNING: <stdin>: Line " line ": " (message)
+            line-end)
+   (info line-start
+         "asciidoc: DEPRECATED: <stdin>: Line " line ": " (message)
+         line-end))
+  :modes adoc-mode)
+
+(flycheck-define-checker asciidoctor
+  "An AsciiDoc syntax checker using the Asciidoctor compiler.
+
+See URL `http://asciidoctor.org'."
+  :command ("asciidoctor" "-o" null-device "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          "asciidoctor: ERROR: <stdin>: Line " line ": " (message)
+          line-end)
+   (warning line-start
+            "asciidoctor: WARNING: <stdin>: Line " line ": " (message)
+            line-end))
+  :modes adoc-mode)
+
+(flycheck-def-args-var flycheck-clang-args c/c++-clang
+  :package-version '(flycheck . "0.22"))
+
+(flycheck-def-option-var flycheck-clang-blocks nil c/c++-clang
+  "Enable blocks in Clang.
+
+When non-nil, enable blocks in Clang with `-fblocks'.  See URL
+`http://clang.llvm.org/docs/BlockLanguageSpec.html' for more
+information about blocks."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-clang-definitions nil c/c++-clang
+  "Additional preprocessor definitions for Clang.
+
+The value of this variable is a list of strings, where each
+string is an additional definition to pass to Clang, via the `-D'
+option."
+  :type '(repeat (string :tag "Definition"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.15"))
+
+(flycheck-def-option-var flycheck-clang-include-path nil c/c++-clang
+  "A list of include directories for Clang.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of Clang.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.14"))
+
+(flycheck-def-option-var flycheck-clang-includes nil c/c++-clang
+  "A list of additional include files for Clang.
+
+The value of this variable is a list of strings, where each
+string is a file to include before syntax checking.  Relative
+paths are relative to the file being checked."
+  :type '(repeat (file :tag "Include file"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.15"))
+
+(flycheck-def-option-var flycheck-clang-language-standard nil c/c++-clang
+  "The language standard to use in Clang.
+
+The value of this variable is either a string denoting a language
+standard, or nil, to use the default standard.  When non-nil,
+pass the language standard via the `-std' option."
+  :type '(choice (const :tag "Default standard" nil)
+                 (string :tag "Language standard"))
+  :safe #'stringp
+  :package-version '(flycheck . "0.15"))
+(make-variable-buffer-local 'flycheck-clang-language-standard)
+
+(flycheck-def-option-var flycheck-clang-ms-extensions nil c/c++-clang
+  "Whether to enable Microsoft extensions to C/C++ in Clang.
+
+When non-nil, enable Microsoft extensions to C/C++ via
+`-fms-extensions'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-def-option-var flycheck-clang-no-exceptions nil c/c++-clang
+  "Whether to disable exceptions in Clang.
+
+When non-nil, disable exceptions for syntax checks, via
+`-fno-exceptions'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-clang-no-rtti nil c/c++-clang
+  "Whether to disable RTTI in Clang.
+
+When non-nil, disable RTTI for syntax checks, via `-fno-rtti'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.15"))
+
+(flycheck-def-option-var flycheck-clang-pedantic nil c/c++-clang
+  "Whether to warn about language extensions in Clang.
+
+For ISO C, follows the version specified by any -std option used.
+When non-nil, disable non-ISO extensions to C/C++ via
+`-pedantic'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-def-option-var flycheck-clang-pedantic-errors nil c/c++-clang
+  "Whether to error on language extensions in Clang.
+
+For ISO C, follows the version specified by any -std option used.
+When non-nil, disable non-ISO extensions to C/C++ via
+`-pedantic-errors'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-def-option-var flycheck-clang-standard-library nil c/c++-clang
+  "The standard library to use for Clang.
+
+The value of this variable is the name of a standard library as
+string, or nil to use the default standard library.
+
+Refer to the Clang manual at URL
+`http://clang.llvm.org/docs/UsersManual.html' for more
+information about the standard library."
+  :type '(choice (const "libc++")
+                 (const :tag "GNU libstdc++" "libstdc++")
+                 (string :tag "Library name"))
+  :safe #'stringp
+  :package-version '(flycheck . "0.15"))
+
+(flycheck-def-option-var flycheck-clang-warnings '("all" "extra") c/c++-clang
+  "A list of additional warnings to enable in Clang.
+
+The value of this variable is a list of strings, where each string
+is the name of a warning category to enable.  By default, all
+recommended warnings and some extra warnings are enabled (as by
+`-Wall' and `-Wextra' respectively).
+
+Refer to the Clang manual at URL
+`http://clang.llvm.org/docs/UsersManual.html' for more
+information about warnings."
+  :type '(choice (const :tag "No additional warnings" nil)
+                 (repeat :tag "Additional warnings"
+                         (string :tag "Warning name")))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.14"))
+
+(defun flycheck-c/c++-quoted-include-directory ()
+  "Get the directory for quoted includes.
+
+C/C++ compiles typicall look up includes with quotation marks in
+the directory of the file being compiled.  However, since
+Flycheck uses temporary copies for syntax checking, it needs to
+explicitly determine the directory for quoted includes.
+
+This function determines the directory by looking at function
+`buffer-file-name', or if that is nil, at `default-directory'."
+  (-if-let (fn (buffer-file-name))
+      (file-name-directory fn)
+    ;; If the buffer has no file name, fall back to its default directory
+    default-directory))
+
+(flycheck-define-checker c/c++-clang
+  "A C/C++ syntax checker using Clang.
+
+See URL `http://clang.llvm.org/'."
+  :command ("clang"
+            "-fsyntax-only"
+            "-fno-color-diagnostics"    ; Do not include color codes in output
+            "-fno-caret-diagnostics"    ; Do not visually indicate the source
+                                        ; location
+            "-fno-diagnostics-show-option" ; Do not show the corresponding
+                                        ; warning group
+            "-iquote" (eval (flycheck-c/c++-quoted-include-directory))
+            (option "-std=" flycheck-clang-language-standard concat)
+            (option-flag "-pedantic" flycheck-clang-pedantic)
+            (option-flag "-pedantic-errors" flycheck-clang-pedantic-errors)
+            (option "-stdlib=" flycheck-clang-standard-library concat)
+            (option-flag "-fms-extensions" flycheck-clang-ms-extensions)
+            (option-flag "-fno-exceptions" flycheck-clang-no-exceptions)
+            (option-flag "-fno-rtti" flycheck-clang-no-rtti)
+            (option-flag "-fblocks" flycheck-clang-blocks)
+            (option-list "-include" flycheck-clang-includes)
+            (option-list "-W" flycheck-clang-warnings concat)
+            (option-list "-D" flycheck-clang-definitions concat)
+            (option-list "-I" flycheck-clang-include-path)
+            (eval flycheck-clang-args)
+            "-x" (eval
+                  (pcase major-mode
+                    (`c++-mode "c++")
+                    (`c-mode "c")))
+            ;; Read from standard input
+            "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (message "In file included from") " " (or "<stdin>" (file-name))
+          ":" line ":" line-end)
+   (info line-start (or "<stdin>" (file-name)) ":" line ":" column
+         ": note: " (optional (message)) line-end)
+   (warning line-start (or "<stdin>" (file-name)) ":" line ":" column
+            ": warning: " (optional (message)) line-end)
+   (error line-start (or "<stdin>" (file-name)) ":" line ":" column
+          ": " (or "fatal error" "error") ": " (optional (message)) line-end))
+  :error-filter
+  (lambda (errors)
+    (let ((errors (flycheck-sanitize-errors errors)))
+      (dolist (err errors)
+        ;; Clang will output empty messages for #error/#warning pragmas without
+        ;; messages.  We fill these empty errors with a dummy message to get
+        ;; them past our error filtering
+        (setf (flycheck-error-message err)
+              (or (flycheck-error-message err) "no message")))
+      (flycheck-fold-include-levels errors "In file included from")))
+  :modes (c-mode c++-mode)
+  :next-checkers ((warning . c/c++-cppcheck)))
+
+(flycheck-def-args-var flycheck-gcc-args c/c++-gcc
+  :package-version '(flycheck . "0.22"))
+
+(flycheck-def-option-var flycheck-gcc-definitions nil c/c++-gcc
+  "Additional preprocessor definitions for GCC.
+
+The value of this variable is a list of strings, where each
+string is an additional definition to pass to GCC, via the `-D'
+option."
+  :type '(repeat (string :tag "Definition"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gcc-include-path nil c/c++-gcc
+  "A list of include directories for GCC.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of gcc.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gcc-includes nil c/c++-gcc
+  "A list of additional include files for GCC.
+
+The value of this variable is a list of strings, where each
+string is a file to include before syntax checking.  Relative
+paths are relative to the file being checked."
+  :type '(repeat (file :tag "Include file"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gcc-language-standard nil c/c++-gcc
+  "The language standard to use in GCC.
+
+The value of this variable is either a string denoting a language
+standard, or nil, to use the default standard.  When non-nil,
+pass the language standard via the `-std' option."
+  :type '(choice (const :tag "Default standard" nil)
+                 (string :tag "Language standard"))
+  :safe #'stringp
+  :package-version '(flycheck . "0.20"))
+(make-variable-buffer-local 'flycheck-gcc-language-standard)
+
+(flycheck-def-option-var flycheck-gcc-no-exceptions nil c/c++-gcc
+  "Whether to disable exceptions in GCC.
+
+When non-nil, disable exceptions for syntax checks, via
+`-fno-exceptions'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gcc-no-rtti nil c/c++-gcc
+  "Whether to disable RTTI in GCC.
+
+When non-nil, disable RTTI for syntax checks, via `-fno-rtti'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gcc-openmp nil c/c++-gcc
+  "Whether to enable OpenMP in GCC.
+
+When non-nil, enable OpenMP for syntax checkers, via
+`-fopenmp'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.21"))
+
+(flycheck-def-option-var flycheck-gcc-pedantic nil c/c++-gcc
+  "Whether to warn about language extensions in GCC.
+
+For ISO C, follows the version specified by any -std option used.
+When non-nil, disable non-ISO extensions to C/C++ via
+`-pedantic'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-def-option-var flycheck-gcc-pedantic-errors nil c/c++-gcc
+  "Whether to error on language extensions in GCC.
+
+For ISO C, follows the version specified by any -std option used.
+When non-nil, disable non-ISO extensions to C/C++ via
+`-pedantic-errors'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-def-option-var flycheck-gcc-warnings '("all" "extra") c/c++-gcc
+  "A list of additional warnings to enable in GCC.
+
+The value of this variable is a list of strings, where each string
+is the name of a warning category to enable.  By default, all
+recommended warnings and some extra warnings are enabled (as by
+`-Wall' and `-Wextra' respectively).
+
+Refer to the gcc manual at URL
+`https://gcc.gnu.org/onlinedocs/gcc/' for more information about
+warnings."
+  :type '(choice (const :tag "No additional warnings" nil)
+                 (repeat :tag "Additional warnings"
+                         (string :tag "Warning name")))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-define-checker c/c++-gcc
+  "A C/C++ syntax checker using GCC.
+
+Requires GCC 4.4 or newer.  See URL `https://gcc.gnu.org/'."
+  :command ("gcc"
+            "-fshow-column"
+            "-iquote" (eval (flycheck-c/c++-quoted-include-directory))
+            (option "-std=" flycheck-gcc-language-standard concat)
+            (option-flag "-pedantic" flycheck-gcc-pedantic)
+            (option-flag "-pedantic-errors" flycheck-gcc-pedantic-errors)
+            (option-flag "-fno-exceptions" flycheck-gcc-no-exceptions)
+            (option-flag "-fno-rtti" flycheck-gcc-no-rtti)
+            (option-flag "-fopenmp" flycheck-gcc-openmp)
+            (option-list "-include" flycheck-gcc-includes)
+            (option-list "-W" flycheck-gcc-warnings concat)
+            (option-list "-D" flycheck-gcc-definitions concat)
+            (option-list "-I" flycheck-gcc-include-path)
+            (eval flycheck-gcc-args)
+            "-x" (eval
+                  (pcase major-mode
+                    (`c++-mode "c++")
+                    (`c-mode "c")))
+            ;; GCC performs full checking only when actually compiling, so
+            ;; `-fsyntax-only' is not enough. Just let it generate assembly
+            ;; code.
+            "-S" "-o" null-device
+            ;; Read from standard input
+            "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (message "In file included from") " " (or "<stdin>" (file-name))
+          ":" line ":" column ":" line-end)
+   (info line-start (or "<stdin>" (file-name)) ":" line ":" column
+         ": note: " (message) line-end)
+   (warning line-start (or "<stdin>" (file-name)) ":" line ":" column
+            ": warning: " (message (one-or-more (not (any "\n["))))
+            (optional "[" (id (one-or-more not-newline)) "]") line-end)
+   (error line-start (or "<stdin>" (file-name)) ":" line ":" column
+          ": " (or "fatal error" "error") ": " (message) line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-fold-include-levels (flycheck-sanitize-errors errors)
+                                  "In file included from"))
+  :modes (c-mode c++-mode)
+  :next-checkers ((warning . c/c++-cppcheck)))
+
+(flycheck-def-option-var flycheck-cppcheck-checks '("style") c/c++-cppcheck
+  "Enabled checks for Cppcheck.
+
+The value of this variable is a list of strings, where each
+string is the name of an additional check to enable.  By default,
+all coding style checks are enabled.
+
+See section \"Enable message\" in the Cppcheck manual at URL
+`http://cppcheck.sourceforge.net/manual.pdf', and the
+documentation of the `--enable' option for more information,
+including a list of supported checks."
+  :type '(repeat :tag "Additional checks"
+                 (string :tag "Check name"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.14"))
+
+(flycheck-def-option-var flycheck-cppcheck-standards nil c/c++-cppcheck
+  "The standards to use in cppcheck.
+
+The value of this variable is either a list of strings denoting
+the standards to use, or nil to pass nothing to cppcheck.  When
+non-nil, pass the standards via one or more `--std=' options."
+  :type '(choice (const :tag "Default" nil)
+                 (repeat :tag "Custom standards"
+                         (string :tag "Standard name")))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "28"))
+(make-variable-buffer-local 'flycheck-cppcheck-standards)
+
+(flycheck-def-option-var flycheck-cppcheck-suppressions-file nil c/c++-cppcheck
+  "The suppressions file to use in cppcheck.
+
+The value of this variable is a file with the suppressions to
+use, or nil to pass nothing to cppcheck.  When non-nil, pass the
+suppressions file via the `--suppressions-list=' option."
+  :type '(choice (const :tag "Default" nil)
+                 (file :tag "Suppressions file"))
+  :safe #'stringp
+  :package-version '(flycheck . "32"))
+(make-variable-buffer-local 'flycheck-cppcheck-suppressions-file)
+
+(flycheck-def-option-var flycheck-cppcheck-suppressions nil c/c++-cppcheck
+  "The suppressions to use in cppcheck.
+
+The value of this variable is either a list of strings denoting
+the suppressions to use, or nil to pass nothing to cppcheck.
+When non-nil, pass the suppressions via one or more `--suppress='
+options."
+  :type '(choice (const :tag "Default" nil)
+                 (repeat :tag "Additional suppressions"
+                         (string :tag "Suppression")))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "28"))
+
+(flycheck-def-option-var flycheck-cppcheck-inconclusive nil c/c++-cppcheck
+  "Whether to enable Cppcheck inconclusive checks.
+
+When non-nil, enable Cppcheck inconclusive checks.  This allows Cppcheck to
+report warnings it's not certain of, but it may result in false positives.
+
+This will have no effect when using Cppcheck 1.53 and older."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.19"))
+
+(flycheck-def-option-var flycheck-cppcheck-include-path nil c/c++-cppcheck
+  "A list of include directories for cppcheck.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of cppcheck.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-define-checker c/c++-cppcheck
+  "A C/C++ checker using cppcheck.
+
+See URL `http://cppcheck.sourceforge.net/'."
+  :command ("cppcheck" "--quiet" "--xml-version=2" "--inline-suppr"
+            (option "--enable=" flycheck-cppcheck-checks concat
+                    flycheck-option-comma-separated-list)
+            (option-flag "--inconclusive" flycheck-cppcheck-inconclusive)
+            (option-list "-I" flycheck-cppcheck-include-path)
+            (option-list "--std=" flycheck-cppcheck-standards concat)
+            (option-list "--suppress=" flycheck-cppcheck-suppressions concat)
+            (option "--suppressions-list="
+                    flycheck-cppcheck-suppressions-file concat)
+            "-x" (eval
+                  (pcase major-mode
+                    (`c++-mode "c++")
+                    (`c-mode "c")))
+            source)
+  :error-parser flycheck-parse-cppcheck
+  :modes (c-mode c++-mode))
+
+(flycheck-define-checker cfengine
+  "A CFEngine syntax checker using cf-promises.
+
+See URL `https://cfengine.com/'."
+  :command ("cf-promises" "-Wall" "-f"
+            ;; We must stay in the same directory to resolve @include
+            source-inplace)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":" column
+            ": warning: " (message) line-end)
+   (error line-start (file-name) ":" line ":" column
+          ": error: " (message) line-end))
+  :modes (cfengine-mode cfengine3-mode))
+
+(flycheck-def-option-var flycheck-foodcritic-tags nil chef-foodcritic
+  "A list of tags to select for Foodcritic.
+
+The value of this variable is a list of strings where each string
+is a tag expression describing Foodcritic rules to enable or
+disable, via the `--tags' option.  To disable a tag, prefix it
+with `~'."
+  :type '(repeat :tag "Tags" (string :tag "Tag expression"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-define-checker chef-foodcritic
+  "A Chef cookbooks syntax checker using Foodcritic.
+
+See URL `http://www.foodcritic.io'."
+  ;; Use `source-inplace' to allow resource discovery with relative paths.
+  ;; foodcritic interprets these as relative to the source file, so we need to
+  ;; stay within the source tree.  See
+  ;; https://github.com/flycheck/flycheck/pull/556
+  :command ("foodcritic"
+            (option-list "--tags" flycheck-foodcritic-tags)
+            source-inplace)
+  :error-patterns
+  ((error line-start (id (one-or-more alnum)) ": "
+          (message) ": " (file-name) ":" line line-end))
+  :modes (enh-ruby-mode ruby-mode)
+  :predicate
+  (lambda ()
+    (let ((parent-dir (file-name-directory
+                       (directory-file-name
+                        (expand-file-name default-directory)))))
+      (or
+       ;; Chef CookBook
+       ;; http://docs.opscode.com/chef/knife.html#id38
+       (locate-dominating-file parent-dir "recipes")
+       ;; Knife Solo
+       ;; http://matschaffer.github.io/knife-solo/#label-Init+command
+       (locate-dominating-file parent-dir "cookbooks")))))
+
+(flycheck-define-checker coffee
+  "A CoffeeScript syntax checker using coffee.
+
+See URL `https://coffeescript.org/'."
+  ;; --print suppresses generation of compiled .js files
+  :command ("coffee" "--compile" "--print" "--stdio")
+  :standard-input t
+  :error-patterns
+  ((error line-start "[stdin]:" line ":" column
+          ": error: " (message) line-end))
+  :modes coffee-mode
+  :next-checkers ((warning . coffee-coffeelint)))
+
+(flycheck-def-config-file-var flycheck-coffeelintrc coffee-coffeelint
+                              ".coffeelint.json"
+  :safe #'stringp)
+
+(flycheck-define-checker coffee-coffeelint
+  "A CoffeeScript style checker using coffeelint.
+
+See URL `http://www.coffeelint.org/'."
+  :command
+  ("coffeelint"
+   (config-file "--file" flycheck-coffeelintrc)
+   "--stdin" "--reporter" "checkstyle")
+  :standard-input t
+  :error-parser flycheck-parse-checkstyle
+  :error-filter (lambda (errors)
+                  (flycheck-remove-error-file-names
+                   "stdin" (flycheck-remove-error-ids
+                            (flycheck-sanitize-errors errors))))
+  :modes coffee-mode)
+
+(flycheck-define-checker coq
+  "A Coq syntax checker using the Coq compiler.
+
+See URL `https://coq.inria.fr/'."
+  ;; We use coqtop in batch mode, because coqc is picky about file names.
+  :command ("coqtop" "-batch" "-load-vernac-source" source)
+  :error-patterns
+  ((error line-start "File \"" (file-name) "\", line " line
+          ;; TODO: Parse the end column, once Flycheck supports that
+          ", characters " column "-" (one-or-more digit) ":\n"
+          (or "Syntax error:" "Error:")
+          ;; Most Coq error messages span multiple lines, and end with a dot.
+          ;; There are simple one-line messages, too, though.
+          (message (or (and (one-or-more (or not-newline "\n")) ".")
+                       (one-or-more not-newline)))
+          line-end))
+  :error-filter
+  (lambda (errors)
+    (dolist (err (flycheck-sanitize-errors errors))
+      (setf (flycheck-error-message err)
+            (replace-regexp-in-string (rx (1+ (syntax whitespace)) line-end)
+                                      "" (flycheck-error-message err)
+                                      'fixedcase 'literal)))
+    (flycheck-increment-error-columns errors))
+  :modes coq-mode)
+
+(flycheck-define-checker css-csslint
+  "A CSS syntax and style checker using csslint.
+
+See URL `https://github.com/CSSLint/csslint'."
+  :command ("csslint" "--format=checkstyle-xml" source)
+  :error-parser flycheck-parse-checkstyle
+  :error-filter flycheck-dequalify-error-ids
+  :modes css-mode)
+
+(defconst flycheck-stylelint-args '("--formatter" "json")
+  "Common arguments to stylelint invocations.")
+
+(flycheck-def-config-file-var flycheck-stylelintrc
+    (css-stylelint scss-stylelint less-stylelint) nil
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-stylelint-quiet
+    nil (css-stylelint scss-stylelint less-stylelint)
+  "Whether to run stylelint in quiet mode.
+
+When non-nil, enable quiet mode, via `--quiet'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . 26))
+
+(defconst flycheck-stylelint-error-re
+  (flycheck-rx-to-string
+   '(: line-start (id (one-or-more word)) ": " (message) line-end)))
+
+(defun flycheck-parse-stylelint (output checker buffer)
+  "Parse stylelint errors from OUTPUT.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+The CHECKER usually returns the errors as JSON.
+
+If the CHECKER throws an Error it returns an Error message with a stacktrace."
+  (condition-case nil
+      (flycheck-parse-stylelint-json output checker buffer)
+
+    ;; The output could not be parsed as JSON
+    (json-error
+
+     ;; Extract a flycheck error from the output (with a regular expression)
+     ;; For match-string 4/5 see flycheck-rx-message/flycheck-rx-id
+     (when (string-match flycheck-stylelint-error-re output)
+       (list (flycheck-error-new-at
+              1 nil 'error
+              (match-string 4 output)
+              :id (match-string 5 output)
+              :checker checker
+              :buffer buffer
+              :filename (buffer-file-name buffer)))))))
+
+(defun flycheck-parse-stylelint-json (output checker buffer)
+  "Parse stylelint JSON errors from OUTPUT.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `http://stylelint.io/developer-guide/formatters/' for information
+about the JSON format of stylelint."
+  (let ((json-object-type 'plist))
+
+    ;; stylelint returns a vector of result objects
+    ;; Since we only passed one file, the first element is enough
+    (let* ((stylelint-output (elt (json-read-from-string output) 0))
+           (filename (buffer-file-name buffer))
+
+           ;; Turn all deprecations into warnings
+           (deprecations
+            (mapcar (lambda (d)
+                      (flycheck-error-new-at
+                       1 nil 'warning
+                       (plist-get d :text)
+                       :id "Deprecation Warning"
+                       :checker checker
+                       :buffer buffer
+                       :filename filename))
+                    (plist-get stylelint-output :deprecations)))
+
+           ;; Turn all invalid options into errors
+           (invalid-options
+            (mapcar (lambda (io)
+                      (flycheck-error-new-at
+                       1 nil 'error
+                       (plist-get io :text)
+                       :id "Invalid Option"
+                       :checker checker
+                       :buffer buffer
+                       :filename filename))
+                    (plist-get stylelint-output :invalidOptionWarnings)))
+
+           ;; Read all linting warnings
+           (warnings
+            (mapcar (lambda (w)
+                      (flycheck-error-new-at
+                       (plist-get w :line) (plist-get w :column)
+                       (pcase (plist-get w :severity)
+                         (`"error"   'error)
+                         (`"warning" 'warning)
+                         ;; Default to info for unknown .severity
+                         (_          'info))
+                       (plist-get w :text)
+                       :id (plist-get w :rule)
+                       :checker checker
+                       :buffer buffer
+                       :filename filename))
+                    (plist-get stylelint-output :warnings))))
+
+      ;; Return the combined errors (deprecations, invalid options, warnings)
+      (append deprecations invalid-options warnings))))
+
+(flycheck-define-checker css-stylelint
+  "A CSS syntax and style checker using stylelint.
+
+See URL `http://stylelint.io/'."
+  :command ("stylelint"
+            (eval flycheck-stylelint-args)
+            (option-flag "--quiet" flycheck-stylelint-quiet)
+            (config-file "--config" flycheck-stylelintrc))
+  :standard-input t
+  :error-parser flycheck-parse-stylelint
+  :modes (css-mode))
+
+(flycheck-def-option-var flycheck-cwl-schema-path nil cwl
+  "A path for the schema file for Common Workflow Language.
+
+The value of this variable is a string that denotes a path for
+the schema file of Common Workflow Language."
+  :type 'string
+  :safe #'stringp)
+
+(flycheck-define-checker cwl
+  "A CWL syntax checker using Schema Salad validator.
+
+Requires Schema Salad 2.6.20171101113912 or newer.
+See URL `https://www.commonwl.org/v1.0/SchemaSalad.html'."
+  :command ("schema-salad-tool"
+            "--quiet"
+            "--print-oneline"
+            (eval flycheck-cwl-schema-path)
+            source-inplace)
+  :error-patterns
+  ((error line-start
+          (file-name) ":" line ":" column ":" (zero-or-more blank)
+          (message (one-or-more not-newline))
+          line-end))
+  :modes cwl-mode)
+
+(defconst flycheck-d-module-re
+  (rx "module" (one-or-more (syntax whitespace))
+      (group (one-or-more (not (syntax whitespace))))
+      (zero-or-more (syntax whitespace))
+      ";")
+  "Regular expression to match a D module declaration.")
+
+(defun flycheck-d-base-directory ()
+  "Get the relative base directory path for this module."
+  (let* ((file-name (buffer-file-name))
+         (module-file (if (string= (file-name-nondirectory file-name)
+                                   "package.d")
+                          (directory-file-name (file-name-directory file-name))
+                        file-name)))
+    (flycheck-module-root-directory
+     (flycheck-find-in-buffer flycheck-d-module-re)
+     module-file)))
+
+(flycheck-def-option-var flycheck-dmd-include-path nil d-dmd
+  "A list of include directories for dmd.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of dmd.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.18"))
+
+(flycheck-def-args-var flycheck-dmd-args d-dmd
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-define-checker d-dmd
+  "A D syntax checker using the DMD compiler.
+
+Requires DMD 2.066 or newer.  See URL `https://dlang.org/'."
+  :command ("dmd"
+            "-debug"                    ; Compile in debug mode
+            "-o-"                       ; Don't generate an object file
+            "-vcolumns"                 ; Add columns in output
+            "-wi" ; Compilation will continue even if there are warnings
+            (eval (concat "-I" (flycheck-d-base-directory)))
+            (option-list "-I" flycheck-dmd-include-path concat)
+            (eval flycheck-dmd-args)
+            source)
+  :error-patterns
+  ((error line-start
+          (file-name) "(" line "," column "): Error: " (message)
+          line-end)
+   (warning line-start (file-name) "(" line "," column "): "
+            (or "Warning" "Deprecation") ": " (message) line-end)
+   (info line-start (file-name) "(" line "," column "): "
+         (one-or-more " ") (message) line-end))
+  :modes d-mode)
+
+(flycheck-define-checker dockerfile-hadolint
+  "A Dockerfile syntax checker using the hadolint.
+
+See URL `http://github.com/hadolint/hadolint/'."
+  :command ("hadolint" "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (file-name) ":" line ":" column " " (message)
+          line-end)
+   (warning line-start
+            (file-name) ":" line " " (id (one-or-more alnum)) " " (message)
+            line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors
+     (flycheck-remove-error-file-names "/dev/stdin" errors)))
+  :modes dockerfile-mode)
+
+(defconst flycheck-this-emacs-executable
+  (concat invocation-directory invocation-name)
+  "The path to the currently running Emacs executable.")
+
+(defconst flycheck-emacs-args '("-Q" "--batch")
+  "Common arguments to Emacs invocations.")
+
+(defmacro flycheck-prepare-emacs-lisp-form (&rest body)
+  "Prepare BODY for use as check form in a subprocess."
+  (declare (indent 0))
+  `(flycheck-sexp-to-string
+    '(progn
+       (defvar jka-compr-inhibit)
+       (unwind-protect
+           ;; Flycheck inhibits compression of temporary files, thus we
+           ;; must not attempt to decompress.
+           (let ((jka-compr-inhibit t))
+             ;; Strip option-argument separator from arguments, if present
+             (when (equal (car command-line-args-left) "--")
+               (setq command-line-args-left (cdr command-line-args-left)))
+             ,@body)
+         ;; Prevent Emacs from processing the arguments on its own, see
+         ;; https://github.com/flycheck/flycheck/issues/319
+         (setq command-line-args-left nil)))))
+
+(defconst flycheck-emacs-lisp-check-form
+  (flycheck-prepare-emacs-lisp-form
+    ;; Keep track of the generated bytecode files, to delete them after byte
+    ;; compilation.
+    (defvar flycheck-byte-compiled-files nil)
+    (let ((byte-compile-dest-file-function
+           (lambda (source)
+             (let ((temp-file (make-temp-file (file-name-nondirectory source))))
+               (push temp-file flycheck-byte-compiled-files)
+               temp-file))))
+      (unwind-protect
+          (byte-compile-file (car command-line-args-left))
+        (mapc (lambda (f) (ignore-errors (delete-file f)))
+              flycheck-byte-compiled-files))
+      (when (bound-and-true-p flycheck-emacs-lisp-check-declare)
+        (check-declare-file (car command-line-args-left))))))
+
+(flycheck-def-option-var flycheck-emacs-lisp-load-path nil emacs-lisp
+  "Load path to use in the Emacs Lisp syntax checker.
+
+When set to `inherit', use the `load-path' of the current Emacs
+session during syntax checking.
+
+When set to a list of strings, add each directory in this list to
+the `load-path' before invoking the byte compiler.  Relative
+paths in this list are expanded against the `default-directory'
+of the buffer to check.
+
+When nil, do not explicitly set the `load-path' during syntax
+checking.  The syntax check only uses the built-in `load-path' of
+Emacs in this case.
+
+Note that changing this variable can lead to wrong results of the
+syntax check, e.g. if an unexpected version of a required library
+is used."
+  :type '(choice (const :tag "Inherit current `load-path'" inherit)
+                 (repeat :tag "Load path" directory))
+  :risky t
+  :package-version '(flycheck . "0.14"))
+
+(flycheck-def-option-var flycheck-emacs-lisp-initialize-packages
+    'auto emacs-lisp
+  "Whether to initialize packages in the Emacs Lisp syntax checker.
+
+When nil, never initialize packages.  When `auto', initialize
+packages only when checking `user-init-file' or files from
+`user-emacs-directory'.  For any other non-nil value, always
+initialize packages.
+
+When initializing packages is enabled the `emacs-lisp' syntax
+checker calls `package-initialize' before byte-compiling the file
+to be checked.  It also sets `package-user-dir' according to
+`flycheck-emacs-lisp-package-user-dir'."
+  :type '(choice (const :tag "Do not initialize packages" nil)
+                 (const :tag "Initialize packages for configuration only" auto)
+                 (const :tag "Always initialize packages" t))
+  :risky t
+  :package-version '(flycheck . "0.14"))
+
+(defconst flycheck-emacs-lisp-package-initialize-form
+  (flycheck-sexp-to-string
+   '(with-demoted-errors "Error during package initialization: %S"
+      (package-initialize)))
+  "Form used to initialize packages.")
+
+(defun flycheck-option-emacs-lisp-package-initialize (value)
+  "Option VALUE filter for `flycheck-emacs-lisp-initialize-packages'."
+  (let ((shall-initialize
+         (if (eq value 'auto)
+             (or (flycheck-in-user-emacs-directory-p (buffer-file-name))
+                 ;; `user-init-file' is nil in non-interactive sessions.  Now,
+                 ;; no user would possibly use Flycheck in a non-interactive
+                 ;; session, but our unit tests run non-interactively, so we
+                 ;; have to handle this case anyway
+                 (and user-init-file
+                      (flycheck-same-files-p (buffer-file-name)
+                                             user-init-file)))
+           value)))
+    (when shall-initialize
+      ;; If packages shall be initialized, return the corresponding form,
+      ;; otherwise make Flycheck ignore the option by returning nil.
+      flycheck-emacs-lisp-package-initialize-form)))
+
+(flycheck-def-option-var flycheck-emacs-lisp-package-user-dir nil emacs-lisp
+  "Package directory for the Emacs Lisp syntax checker.
+
+If set to a string set `package-user-dir' to the value of this
+variable before initializing packages. If set to nil just inherit
+the value of `package-user-dir' from the running Emacs session.
+
+This variable has no effect, if
+`flycheck-emacs-lisp-initialize-packages' is nil."
+  :type '(choice (const :tag "Default package directory" nil)
+                 (directory :tag "Custom package directory"))
+  :risky t
+  :package-version '(flycheck . "0.14"))
+
+(defun flycheck-option-emacs-lisp-package-user-dir (value)
+  "Option VALUE filter for `flycheck-emacs-lisp-package-user-dir'."
+  ;; Inherit the package directory from our Emacs session
+  (let ((value (or value (bound-and-true-p package-user-dir))))
+    (when value
+      (flycheck-sexp-to-string `(setq package-user-dir ,value)))))
+
+(flycheck-def-option-var flycheck-emacs-lisp-check-declare nil emacs-lisp
+  "If non-nil, check ‘declare-function’ forms using ‘check-declare-file’."
+  :type '(choice (const :tag "Do not check declare forms" nil)
+                 (const :tag "Check declare forms" t))
+  :risky t
+  :package-version '(flycheck . "31"))
+
+(defun flycheck-option-emacs-lisp-check-declare (value)
+  "Option VALUE filter for `flycheck-emacs-lisp-check-declare'."
+  (when value
+    (flycheck-sexp-to-string
+     `(progn
+        (defvar flycheck-emacs-lisp-check-declare)
+        (setq flycheck-emacs-lisp-check-declare ,value)))))
+
+(flycheck-define-checker emacs-lisp
+  "An Emacs Lisp syntax checker using the Emacs Lisp Byte compiler.
+
+See Info Node `(elisp)Byte Compilation'."
+  :command ("emacs" (eval flycheck-emacs-args)
+            (eval
+             (let ((path (pcase flycheck-emacs-lisp-load-path
+                           (`inherit load-path)
+                           (p (seq-map #'expand-file-name p)))))
+               (flycheck-prepend-with-option "--directory" path)))
+            (option "--eval" flycheck-emacs-lisp-package-user-dir nil
+                    flycheck-option-emacs-lisp-package-user-dir)
+            (option "--eval" flycheck-emacs-lisp-initialize-packages nil
+                    flycheck-option-emacs-lisp-package-initialize)
+            (option "--eval" flycheck-emacs-lisp-check-declare nil
+                    flycheck-option-emacs-lisp-check-declare)
+            "--eval" (eval flycheck-emacs-lisp-check-form)
+            "--"
+            source-inplace)
+  :error-patterns
+  ((error line-start (file-name) ":" line ":" column ":Error:"
+          (message (zero-or-more not-newline)
+                   (zero-or-more "\n    " (zero-or-more not-newline)))
+          line-end)
+   (warning line-start (file-name) ":" line ":" column ":Warning:"
+            (message (zero-or-more not-newline)
+                     (zero-or-more "\n    " (zero-or-more not-newline)))
+            line-end)
+   (warning line-start (file-name) ":" line (optional ":" column)
+            ":Warning (check-declare): said\n"
+            (message (zero-or-more "    " (zero-or-more not-newline))
+                     (zero-or-more "\n    " (zero-or-more not-newline)))
+            line-end)
+   ;; The following is for Emacs 24 ‘check-declare-file’, which uses a
+   ;; less informative format.
+   (warning line-start "Warning (check-declare): " (file-name) " said "
+            (message (zero-or-more not-newline))
+            line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-fill-empty-line-numbers
+     (flycheck-collapse-error-message-whitespace
+      (flycheck-sanitize-errors errors))))
+  :modes (emacs-lisp-mode lisp-interaction-mode)
+  :predicate
+  (lambda ()
+    (and
+     ;; Ensure that we only check buffers with a backing file.  For buffers
+     ;; without a backing file we cannot guarantee that file names in error
+     ;; messages are properly resolved, because `byte-compile-file' emits file
+     ;; names *relative to the directory of the checked file* instead of the
+     ;; working directory.  Hence our backwards-substitution will fail, because
+     ;; the checker process has a different base directory to resolve relative
+     ;; file names than the Flycheck code working on the buffer to check.
+     (buffer-file-name)
+     ;; Do not check buffers which should not be byte-compiled.  The checker
+     ;; process will refuse to compile these, which would confuse Flycheck
+     (not (bound-and-true-p no-byte-compile))
+     ;; Do not check buffers used for autoloads generation during package
+     ;; installation.  These buffers are too short-lived for being checked, and
+     ;; doing so causes spurious errors.  See
+     ;; https://github.com/flycheck/flycheck/issues/45 and
+     ;; https://github.com/bbatsov/prelude/issues/248.  We must also not check
+     ;; compilation buffers, but as these are ephemeral, Flycheck won't check
+     ;; them anyway.
+     (not (flycheck-autoloads-file-p))))
+  :next-checkers (emacs-lisp-checkdoc))
+
+(defconst flycheck-emacs-lisp-checkdoc-form
+  (flycheck-prepare-emacs-lisp-form
+    (unless (require 'elisp-mode nil 'no-error)
+      ;; TODO: Fallback for Emacs 24, remove when dropping support for 24
+      (require 'lisp-mode))
+    (require 'checkdoc)
+
+    (let ((source (car command-line-args-left))
+          ;; Remember the default directory of the process
+          (process-default-directory default-directory))
+      ;; Note that we deliberately use our custom approach even despite of
+      ;; `checkdoc-file' which was added to Emacs 25.1.  While it's conceptually
+      ;; the better thing, its implementation has too many flaws to be of use
+      ;; for us.
+      (with-temp-buffer
+        (insert-file-contents source 'visit)
+        (setq buffer-file-name source)
+        ;; And change back to the process default directory to make file-name
+        ;; back-substutition work
+        (setq default-directory process-default-directory)
+        (with-demoted-errors "Error in checkdoc: %S"
+          ;; Checkdoc needs the Emacs Lisp syntax table and comment syntax to
+          ;; parse sexps and identify docstrings correctly; see
+          ;; https://github.com/flycheck/flycheck/issues/833
+          (delay-mode-hooks (emacs-lisp-mode))
+          (setq delayed-mode-hooks nil)
+          (checkdoc-current-buffer t)
+          (with-current-buffer checkdoc-diagnostic-buffer
+            (princ (buffer-substring-no-properties (point-min) (point-max)))
+            (kill-buffer)))))))
+
+(defconst flycheck-emacs-lisp-checkdoc-variables
+  '(checkdoc-symbol-words
+    checkdoc-arguments-in-order-flag
+    checkdoc-force-history-flag
+    checkdoc-permit-comma-termination-flag
+    checkdoc-force-docstrings-flag
+    checkdoc-package-keywords-flag
+    checkdoc-spellcheck-documentation-flag
+    checkdoc-verb-check-experimental-flag
+    checkdoc-max-keyref-before-warn
+    sentence-end-double-space)
+  "Variables inherited by the checkdoc subprocess.")
+
+(defun flycheck-emacs-lisp-checkdoc-variables-form ()
+  "Make a sexp to pass relevant variables to a checkdoc subprocess.
+
+Variables are taken from `flycheck-emacs-lisp-checkdoc-variables'."
+  `(progn
+     ,@(seq-map (lambda (opt) `(setq-default ,opt ',(symbol-value opt)))
+                (seq-filter #'boundp flycheck-emacs-lisp-checkdoc-variables))))
+
+(flycheck-define-checker emacs-lisp-checkdoc
+  "An Emacs Lisp style checker using CheckDoc.
+
+The checker runs `checkdoc-current-buffer'."
+  :command ("emacs" (eval flycheck-emacs-args)
+            "--eval" (eval (flycheck-sexp-to-string
+                            (flycheck-emacs-lisp-checkdoc-variables-form)))
+            "--eval" (eval flycheck-emacs-lisp-checkdoc-form)
+            "--" source)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ": " (message) line-end))
+  :modes (emacs-lisp-mode)
+  :predicate
+  (lambda ()
+    ;; Do not check Autoloads, Cask/Carton and dir-locals files.  These files
+    ;; really don't need to follow Checkdoc conventions.
+    (not (or (flycheck-autoloads-file-p)
+             (and (buffer-file-name)
+                  (member (file-name-nondirectory (buffer-file-name))
+                          '("Cask" "Carton" ".dir-locals.el")))))))
+
+(dolist (checker '(emacs-lisp emacs-lisp-checkdoc))
+  (setf (car (flycheck-checker-get checker 'command))
+        flycheck-this-emacs-executable))
+
+(flycheck-def-option-var flycheck-erlang-include-path nil erlang
+  "A list of include directories for Erlang.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of erlc.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-def-option-var flycheck-erlang-library-path nil erlang
+  "A list of library directories for Erlang.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the library path of erlc.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Library directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-define-checker erlang
+  "An Erlang syntax checker using the Erlang interpreter.
+
+See URL `http://www.erlang.org/'."
+  :command ("erlc"
+            "-o" temporary-directory
+            (option-list "-I" flycheck-erlang-include-path)
+            (option-list "-pa" flycheck-erlang-library-path)
+            "-Wall"
+            source)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ": Warning:" (message) line-end)
+   (error line-start (file-name) ":" line ": " (message) line-end))
+  :modes erlang-mode
+  :enabled (lambda () (string-suffix-p ".erl" (buffer-file-name))))
+
+(defun contains-rebar-config (dir-name)
+  "Return DIR-NAME if DIR-NAME/rebar.config exists, nil otherwise."
+  (when (file-exists-p (expand-file-name "rebar.config" dir-name))
+    dir-name))
+
+(defun locate-rebar3-project-root (file-name &optional prev-file-name acc)
+  "Find the top-most rebar project root for source FILE-NAME.
+
+A project root directory is any directory containing a
+rebar.config file.  Find the top-most directory to move out of any
+nested dependencies.
+
+FILE-NAME is a source file for which to find the project.
+
+PREV-FILE-NAME helps us prevent infinite looping
+
+ACC is an accumulator that keeps the list of results, the first
+non-nil of which will be our project root.
+
+Return the absolute path to the directory"
+  (if (string= file-name prev-file-name)
+      (car (remove nil acc))
+    (let ((current-dir (file-name-directory file-name)))
+      (locate-rebar3-project-root
+       (directory-file-name current-dir)
+       file-name
+       (cons (contains-rebar-config current-dir) acc)))))
+
+(defun flycheck-rebar3-project-root (&optional _checker)
+  "Return directory where rebar.config is located."
+  (locate-rebar3-project-root buffer-file-name))
+
+(flycheck-define-checker erlang-rebar3
+  "An Erlang syntax checker using the rebar3 build tool."
+  :command ("rebar3" "compile")
+  :error-parser
+  (lambda (output checker buffer)
+    ;; rebar3 outputs ANSI terminal colors, which don't match up with
+    ;; :error-patterns, so we strip those color codes from the output
+    ;; here before passing it along to the default behavior. The
+    ;; relevant discussion can be found at
+    ;; https://github.com/flycheck/flycheck/pull/1144
+    (require 'ansi-color)
+    (flycheck-parse-with-patterns
+     (and (fboundp 'ansi-color-filter-apply) (ansi-color-filter-apply output))
+     checker buffer))
+  :error-patterns
+  ((warning line-start
+            (file-name) ":" line ": Warning:" (message) line-end)
+   (error line-start
+          (file-name) ":" line ": " (message) line-end))
+  :modes erlang-mode
+  :enabled flycheck-rebar3-project-root
+  :predicate flycheck-buffer-saved-p
+  :working-directory flycheck-rebar3-project-root)
+
+(flycheck-define-checker eruby-erubis
+  "An eRuby syntax checker using the `erubis' command.
+
+See URL `http://www.kuwata-lab.com/erubis/'."
+  :command ("erubis" "-z" source)
+  :error-patterns
+  ((error line-start (file-name) ":" line ": " (message) line-end))
+  :modes (html-erb-mode rhtml-mode))
+
+(flycheck-def-args-var flycheck-gfortran-args fortran-gfortran
+  :package-version '(flycheck . "0.22"))
+
+(flycheck-def-option-var flycheck-gfortran-include-path nil fortran-gfortran
+  "A list of include directories for GCC Fortran.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of gcc.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gfortran-language-standard "f95"
+                         fortran-gfortran
+  "The language standard to use in GFortran.
+
+The value of this variable is either a string denoting a language
+standard, or nil, to use the default standard.  When non-nil,
+pass the language standard via the `-std' option."
+  :type '(choice (const :tag "Default standard" nil)
+                 (string :tag "Language standard"))
+  :safe #'stringp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-def-option-var flycheck-gfortran-layout nil fortran-gfortran
+  "The source code layout to use in GFortran.
+
+The value of this variable is one of the following symbols:
+
+nil
+     Let gfortran determine the layout from the extension
+
+`free'
+     Use free form layout
+
+
+`fixed'
+     Use fixed form layout
+
+In any other case, an error is signaled."
+  :type '(choice (const :tag "Guess layout from extension" nil)
+                 (const :tag "Free form layout" free)
+                 (const :tag "Fixed form layout" fixed))
+  :safe (lambda (value) (or (not value) (memq value '(free fixed))))
+  :package-version '(flycheck . "0.20"))
+
+(defun flycheck-option-gfortran-layout (value)
+  "Option VALUE filter for `flycheck-gfortran-layout'."
+  (pcase value
+    (`nil nil)
+    (`free "free-form")
+    (`fixed "fixed-form")
+    (_ (error "Invalid value for flycheck-gfortran-layout: %S" value))))
+
+(flycheck-def-option-var flycheck-gfortran-warnings '("all" "extra")
+                         fortran-gfortran
+  "A list of warnings for GCC Fortran.
+
+The value of this variable is a list of strings, where each string
+is the name of a warning category to enable.  By default, all
+recommended warnings and some extra warnings are enabled (as by
+`-Wall' and `-Wextra' respectively).
+
+Refer to the gfortran manual at URL
+`https://gcc.gnu.org/onlinedocs/gfortran/' for more information
+about warnings"
+  :type '(choice (const :tag "No additional warnings" nil)
+                 (repeat :tag "Additional warnings"
+                         (string :tag "Warning name")))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-define-checker fortran-gfortran
+  "An Fortran syntax checker using GCC.
+
+Uses GCC's Fortran compiler gfortran.  See URL
+`https://gcc.gnu.org/onlinedocs/gfortran/'."
+  :command ("gfortran"
+            "-fsyntax-only"
+            "-fshow-column"
+            ;; Do not visually indicate the source location
+            "-fno-diagnostics-show-caret"
+            ;; Do not show the corresponding warning group
+            "-fno-diagnostics-show-option"
+            ;; Fortran has similar include processing as C/C++
+            "-iquote" (eval (flycheck-c/c++-quoted-include-directory))
+            (option "-std=" flycheck-gfortran-language-standard concat)
+            (option "-f" flycheck-gfortran-layout concat
+                    flycheck-option-gfortran-layout)
+            (option-list "-W" flycheck-gfortran-warnings concat)
+            (option-list "-I" flycheck-gfortran-include-path concat)
+            (eval flycheck-gfortran-args)
+            source)
+  :error-patterns
+  ((error line-start (file-name) ":" line (or ":" ".") column (or ": " ":\n")
+          (or (= 3 (zero-or-more not-newline) "\n") "")
+          (or "Error" "Fatal Error") ": "
+          (message) line-end)
+   (warning line-start (file-name) ":" line (or ":" ".") column (or ": " ":\n")
+            (or (= 3 (zero-or-more not-newline) "\n") "")
+            "Warning: " (message) line-end))
+  :modes (fortran-mode f90-mode))
+
+(flycheck-define-checker go-gofmt
+  "A Go syntax and style checker using the gofmt utility.
+
+See URL `https://golang.org/cmd/gofmt/'."
+  :command ("gofmt")
+  :standard-input t
+  :error-patterns
+  ((error line-start "<standard input>:" line ":" column ": "
+          (message) line-end))
+  :modes go-mode
+  :next-checkers ((warning . go-golint)
+                  ;; Fall back, if go-golint doesn't exist
+                  (warning . go-vet)
+                  ;; Fall back, if go-vet doesn't exist
+                  (warning . go-build) (warning . go-test)
+                  (warning . go-errcheck)
+                  (warning . go-unconvert)
+                  (warning . go-megacheck)))
+
+(flycheck-define-checker go-golint
+  "A Go style checker using Golint.
+
+See URL `https://github.com/golang/lint'."
+  :command ("golint" source)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":" column ": " (message) line-end))
+  :modes go-mode
+  :next-checkers (go-vet
+                  ;; Fall back, if go-vet doesn't exist
+                  go-build go-test go-errcheck go-unconvert go-megacheck))
+
+(flycheck-def-option-var flycheck-go-vet-print-functions nil go-vet
+  "A list of print-like functions for `go tool vet'.
+
+Go vet will check these functions for format string problems and
+issues, such as a mismatch between the number of formats used,
+and the number of arguments given.
+
+Each entry is in the form Name:N where N is the zero-based
+argument position of the first argument involved in the print:
+either the format or the first print argument for non-formatted
+prints.  For example, if you have Warn and Warnf functions that
+take an io.Writer as their first argument, like Fprintf,
+-printfuncs=Warn:1,Warnf:1 "
+  :type '(repeat :tag "print-like functions"
+                 (string :tag "function"))
+  :safe #'flycheck-string-list-p)
+
+(flycheck-def-option-var flycheck-go-vet-shadow nil go-vet
+  "Whether to check for shadowed variables with `go tool vet'.
+
+When non-nil check for shadowed variables.  When `strict' check
+more strictly, which can very noisy.  When nil do not check for
+shadowed variables.
+
+This option requires Go 1.6 or newer."
+  :type '(choice (const :tag "Do not check for shadowed variables" nil)
+                 (const :tag "Check for shadowed variables" t)
+                 (const :tag "Strictly check for shadowed variables" strict)))
+
+(flycheck-def-option-var flycheck-go-megacheck-disabled-checkers nil
+                         go-megacheck
+  "A list of checkers to disable when running `megacheck'.
+
+The value of this variable is a list of strings, where each
+string is a checker to be disabled. Valid checkers are `simple',
+`staticcheck' and `unused'. When nil, all checkers will be
+enabled. "
+  :type '(set (const :tag "Disable simple" "simple")
+              (const :tag "Disable staticcheck" "staticcheck")
+              (const :tag "Disable unused" "unused"))
+  :safe #'flycheck-string-list-p)
+
+(flycheck-define-checker go-vet
+  "A Go syntax checker using the `go tool vet' command.
+
+See URL `https://golang.org/cmd/go/' and URL
+`https://golang.org/cmd/vet/'."
+  :command ("go" "tool" "vet" "-all"
+            (option "-printfuncs=" flycheck-go-vet-print-functions concat
+                    flycheck-option-comma-separated-list)
+            (option-flag "-shadow" flycheck-go-vet-shadow)
+            (option-list "-tags=" flycheck-go-build-tags concat)
+            (eval (when (eq flycheck-go-vet-shadow 'strict) "-shadowstrict"))
+            source)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ": " (message) line-end))
+  :modes go-mode
+  ;; We must explicitly check whether the "vet" tool is available
+  :predicate (lambda ()
+               (let ((go (flycheck-checker-executable 'go-vet)))
+                 (member "vet" (ignore-errors (process-lines go "tool")))))
+  :next-checkers (go-build
+                  go-test
+                  ;; Fall back if `go build' or `go test' can be used
+                  go-errcheck
+                  go-unconvert
+                  go-megacheck)
+  :verify (lambda (_)
+            (let* ((go (flycheck-checker-executable 'go-vet))
+                   (have-vet (member "vet" (ignore-errors
+                                             (process-lines go "tool")))))
+              (list
+               (flycheck-verification-result-new
+                :label "go tool vet"
+                :message (if have-vet "present" "missing")
+                :face (if have-vet 'success '(bold error)))))))
+
+(flycheck-def-option-var flycheck-go-build-install-deps nil (go-build go-test)
+  "Whether to install dependencies in `go build' and `go test'.
+
+If non-nil automatically install dependencies with `go build'
+while syntax checking."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.25"))
+
+(flycheck-def-option-var flycheck-go-build-tags nil go-build
+  "A list of tags for `go build'.
+
+Each item is a string with a tag to be given to `go build'."
+  :type '(repeat (string :tag "Tag"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.25"))
+
+(flycheck-define-checker go-build
+  "A Go syntax and type checker using the `go build' command.
+
+Requires Go 1.6 or newer.  See URL `https://golang.org/cmd/go'."
+  :command ("go" "build"
+            (option-flag "-i" flycheck-go-build-install-deps)
+            ;; multiple tags are listed as "dev debug ..."
+            (option-list "-tags=" flycheck-go-build-tags concat)
+            "-o" null-device)
+  :error-patterns
+  ((error line-start (file-name) ":" line ":"
+          (optional column ":") " "
+          (message (one-or-more not-newline)
+                   (zero-or-more "\n\t" (one-or-more not-newline)))
+          line-end)
+   ;; Catch error message about multiple packages in a directory, which doesn't
+   ;; follow the standard error message format.
+   (info line-start
+         (message "can't load package: package "
+                  (one-or-more (not (any ?: ?\n)))
+                  ": found packages "
+                  (one-or-more not-newline))
+         line-end))
+  :error-filter
+  (lambda (errors)
+    (dolist (error errors)
+      (unless (flycheck-error-line error)
+        ;; Flycheck ignores errors without line numbers, but the error
+        ;; message about multiple packages in a directory doesn't come with a
+        ;; line number, so inject a fake one.
+        (setf (flycheck-error-line error) 1)))
+    errors)
+  :modes go-mode
+  :predicate (lambda ()
+               (and (flycheck-buffer-saved-p)
+                    (not (string-suffix-p "_test.go" (buffer-file-name)))))
+  :next-checkers ((warning . go-errcheck)
+                  (warning . go-unconvert)
+                  (warning . go-megacheck)))
+
+(flycheck-define-checker go-test
+  "A Go syntax and type checker using the `go test' command.
+
+Requires Go 1.6 or newer.  See URL `https://golang.org/cmd/go'."
+  :command ("go" "test"
+            (option-flag "-i" flycheck-go-build-install-deps)
+            (option-list "-tags=" flycheck-go-build-tags concat)
+            "-c" "-o" null-device)
+  :error-patterns
+  ((error line-start (file-name) ":" line ":"
+          (optional column ":") " "
+          (message (one-or-more not-newline)
+                   (zero-or-more "\n\t" (one-or-more not-newline)))
+          line-end))
+  :modes go-mode
+  :predicate
+  (lambda () (and (flycheck-buffer-saved-p)
+                  (string-suffix-p "_test.go" (buffer-file-name))))
+  :next-checkers ((warning . go-errcheck)
+                  (warning . go-unconvert)
+                  (warning . go-megacheck)))
+
+(flycheck-define-checker go-errcheck
+  "A Go checker for unchecked errors.
+
+Requires errcheck newer than commit 8515d34 (Aug 28th, 2015).
+
+See URL `https://github.com/kisielk/errcheck'."
+  :command ("errcheck"
+            "-abspath"
+            (option-list "-tags=" flycheck-go-build-tags concat)
+            ".")
+  :error-patterns
+  ((warning line-start
+            (file-name) ":" line ":" column (or (one-or-more "\t") ": " ":\t")
+            (message)
+            line-end))
+  :error-filter
+  (lambda (errors)
+    (let ((errors (flycheck-sanitize-errors errors)))
+      (dolist (err errors)
+        (-when-let (message (flycheck-error-message err))
+          ;; Improve the messages reported by errcheck to make them more clear.
+          (setf (flycheck-error-message err)
+                (format "Ignored `error` returned from `%s`" message)))))
+    errors)
+  :modes go-mode
+  :predicate (lambda () (flycheck-buffer-saved-p))
+  :next-checkers ((warning . go-unconvert)
+                  (warning . go-megacheck)))
+
+(flycheck-define-checker go-unconvert
+  "A Go checker looking for unnecessary type conversions.
+
+See URL `https://github.com/mdempsky/unconvert'."
+  :command ("unconvert" ".")
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":" column ": " (message) line-end))
+  :modes go-mode
+  :predicate (lambda () (flycheck-buffer-saved-p))
+  :next-checkers ((warning . go-megacheck)))
+
+(flycheck-define-checker go-megacheck
+  "A Go checker that performs static analysis and linting using the `megacheck'
+command.
+
+Requires Go 1.6 or newer. See URL
+`https://github.com/dominikh/go-tools'."
+  :command ("megacheck"
+            (option-list "-tags=" flycheck-go-build-tags concat)
+            (eval (mapcar (lambda (checker) (concat "-" checker
+                                                    ".enabled=false"))
+                          flycheck-go-megacheck-disabled-checkers))
+            ;; Run in current directory to make megacheck aware of symbols
+            ;; declared in other files.
+            ".")
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":" column ": " (message) line-end))
+  :modes go-mode)
+
+(flycheck-define-checker groovy
+  "A groovy syntax checker using groovy compiler API.
+
+See URL `http://www.groovy-lang.org'."
+  :command ("groovy" "-e"
+            "import org.codehaus.groovy.control.*
+
+unit = new CompilationUnit()
+unit.addSource(\"input\", System.in)
+
+try {
+    unit.compile(Phases.CONVERSION)
+} catch (MultipleCompilationErrorsException e) {
+    e.errorCollector.write(new PrintWriter(System.out, true), null)
+}")
+  :standard-input t
+  :error-patterns
+  ((error line-start "input: " line ":" (message)
+          " @ line " line ", column " column "." line-end))
+  :modes groovy-mode)
+
+(flycheck-define-checker haml
+  "A Haml syntax checker using the Haml compiler.
+
+See URL `http://haml.info'."
+  :command ("haml" "-c" "--stdin")
+  :standard-input t
+  :error-patterns
+  ((error line-start "Syntax error on line " line ": " (message) line-end)
+   (error line-start ":" line ": syntax error, " (message) line-end))
+  :modes haml-mode)
+
+(flycheck-define-checker handlebars
+  "A Handlebars syntax checker using the Handlebars compiler.
+
+See URL `http://handlebarsjs.com/'."
+  :command ("handlebars" "-i-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          "Error: Parse error on line " line ":" (optional "\r") "\n"
+          (zero-or-more not-newline) "\n" (zero-or-more not-newline) "\n"
+          (message) line-end))
+  :modes (handlebars-mode handlebars-sgml-mode web-mode)
+  :predicate
+  (lambda ()
+    (if (eq major-mode 'web-mode)
+        ;; Check if this is a handlebars file since web-mode does not store the
+        ;; non-canonical engine name
+        (let* ((regexp-alist (bound-and-true-p web-mode-engine-file-regexps))
+               (pattern (cdr (assoc "handlebars" regexp-alist))))
+          (and pattern (buffer-file-name)
+               (string-match-p pattern (buffer-file-name))))
+      t)))
+
+(defconst flycheck-haskell-module-re
+  (rx line-start (zero-or-more (or "\n" (any space)))
+      "module" (one-or-more (or "\n" (any space)))
+      (group (one-or-more (not (any space "(" "\n")))))
+  "Regular expression for a Haskell module name.")
+
+(flycheck-def-args-var flycheck-ghc-args (haskell-stack-ghc haskell-ghc)
+  :package-version '(flycheck . "0.22"))
+
+(flycheck-def-option-var flycheck-ghc-stack-use-nix nil haskell-stack-ghc
+  "Whether to enable nix support in stack.
+
+When non-nil, stack will append '--nix' flag to any call."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "26"))
+
+(flycheck-def-option-var flycheck-ghc-stack-project-file nil haskell-stack-ghc
+  "Override project stack.yaml file.
+
+The value of this variable is a file path that refers to a yaml
+file for the current stack project. Relative file paths are
+resolved against the checker's working directory. When non-nil,
+stack will get overridden value via `--stack-yaml'."
+  :type 'string
+  :safe #'stringp
+  :package-version '(flycheck . "32"))
+
+(flycheck-def-option-var flycheck-ghc-no-user-package-database nil haskell-ghc
+  "Whether to disable the user package database in GHC.
+
+When non-nil, disable the user package database in GHC, via
+`-no-user-package-db'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-def-option-var flycheck-ghc-package-databases nil haskell-ghc
+  "Additional module databases for GHC.
+
+The value of this variable is a list of strings, where each
+string is a directory of a package database.  Each package
+database is given to GHC via `-package-db'."
+  :type '(repeat (directory :tag "Package database"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-def-option-var flycheck-ghc-search-path nil
+                         (haskell-stack-ghc haskell-ghc)
+  "Module search path for (Stack) GHC.
+
+The value of this variable is a list of strings, where each
+string is a directory containing Haskell modules.  Each directory
+is added to the GHC search path via `-i'."
+  :type '(repeat (directory :tag "Module directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-def-option-var flycheck-ghc-language-extensions nil
+                         (haskell-stack-ghc haskell-ghc)
+  "Language extensions for (Stack) GHC.
+
+The value of this variable is a list of strings, where each
+string is a Haskell language extension, as in the LANGUAGE
+pragma.  Each extension is enabled via `-X'."
+  :type '(repeat (string :tag "Language extension"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.19"))
+
+(defvar flycheck-haskell-ghc-cache-directory nil
+  "The cache directory for `ghc' output.")
+
+(defun flycheck-haskell-ghc-cache-directory ()
+  "Get the cache location for `ghc' output.
+
+If no cache directory exists yet, create one and return it.
+Otherwise return the previously used cache directory."
+  (setq flycheck-haskell-ghc-cache-directory
+        (or flycheck-haskell-ghc-cache-directory
+            (make-temp-file "flycheck-haskell-ghc-cache" 'directory))))
+
+(defun flycheck--locate-dominating-file-matching (directory regexp)
+  "Search for a file in directory hierarchy starting at DIRECTORY.
+
+Look up the directory hierarchy from DIRECTORY for a directory
+containing a file that matches REGEXP."
+  (locate-dominating-file
+   directory
+   (lambda (dir)
+     (directory-files dir nil regexp t))))
+
+(defun flycheck-haskell--find-default-directory (checker)
+  "Come up with a suitable default directory for Haskell to run CHECKER in.
+
+In case of `haskell-stack-ghc' checker it is directory with
+stack.yaml file.  If there's no stack.yaml file in any parent
+directory, it will be the directory that \"stack path --project-root\"
+command returns.
+
+For all other checkers, it is the closest parent directory that
+contains a cabal file."
+  (pcase checker
+    (`haskell-stack-ghc
+     (or
+      (when (buffer-file-name)
+        (flycheck--locate-dominating-file-matching
+         (file-name-directory (buffer-file-name))
+         "stack.*\\.yaml\\'"))
+      (-when-let* ((stack (funcall flycheck-executable-find "stack"))
+                   (output (ignore-errors
+                             (process-lines stack
+                                            "--no-install-ghc"
+                                            "path" "--project-root")))
+                   (stack-dir (car output)))
+        (and (file-directory-p stack-dir) stack-dir))))
+    (_
+     (when (buffer-file-name)
+       (flycheck--locate-dominating-file-matching
+        (file-name-directory (buffer-file-name))
+        "\\.cabal\\'\\|\\`package\\.yaml\\'")))))
+
+(flycheck-define-checker haskell-stack-ghc
+  "A Haskell syntax and type checker using `stack ghc'.
+
+See URL `https://github.com/commercialhaskell/stack'."
+  :command ("stack"
+            "--no-install-ghc"
+            (option "--stack-yaml" flycheck-ghc-stack-project-file)
+            (option-flag "--nix" flycheck-ghc-stack-use-nix)
+            "ghc" "--" "-Wall" "-no-link"
+            "-outputdir" (eval (flycheck-haskell-ghc-cache-directory))
+            (option-list "-X" flycheck-ghc-language-extensions concat)
+            (option-list "-i" flycheck-ghc-search-path concat)
+            (eval (concat
+                   "-i"
+                   (flycheck-module-root-directory
+                    (flycheck-find-in-buffer flycheck-haskell-module-re))))
+            (eval flycheck-ghc-args)
+            "-x" (eval
+                  (pcase major-mode
+                    (`haskell-mode "hs")
+                    (`literate-haskell-mode "lhs")))
+            source)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":" column ":"
+            (or " " "\n    ") (in "Ww") "arning:"
+            (optional " " "[" (id (one-or-more not-newline)) "]")
+            (optional "\n")
+            (message
+             (one-or-more " ") (one-or-more not-newline)
+             (zero-or-more "\n"
+                           (one-or-more " ")
+                           (one-or-more (not (any ?\n ?|)))))
+            line-end)
+   (error line-start (file-name) ":" line ":" column ":" (optional " error:")
+          (or (message (one-or-more not-newline))
+              (and "\n"
+                   (message
+                    (one-or-more " ") (one-or-more not-newline)
+                    (zero-or-more "\n"
+                                  (one-or-more " ")
+                                  (one-or-more (not (any ?\n ?|)))))))
+          line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors (flycheck-dedent-error-messages errors)))
+  :modes (haskell-mode literate-haskell-mode)
+  :next-checkers ((warning . haskell-hlint))
+  :working-directory flycheck-haskell--find-default-directory)
+
+(flycheck-define-checker haskell-ghc
+  "A Haskell syntax and type checker using ghc.
+
+See URL `https://www.haskell.org/ghc/'."
+  :command ("ghc" "-Wall" "-no-link"
+            "-outputdir" (eval (flycheck-haskell-ghc-cache-directory))
+            (option-flag "-no-user-package-db"
+                         flycheck-ghc-no-user-package-database)
+            (option-list "-package-db" flycheck-ghc-package-databases)
+            (option-list "-i" flycheck-ghc-search-path concat)
+            ;; Include the parent directory of the current module tree, to
+            ;; properly resolve local imports
+            (eval (concat
+                   "-i"
+                   (flycheck-module-root-directory
+                    (flycheck-find-in-buffer flycheck-haskell-module-re))))
+            (option-list "-X" flycheck-ghc-language-extensions concat)
+            (eval flycheck-ghc-args)
+            "-x" (eval
+                  (pcase major-mode
+                    (`haskell-mode "hs")
+                    (`literate-haskell-mode "lhs")))
+            source)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":" column ":"
+            (or " " "\n    ") (in "Ww") "arning:"
+            (optional " " "[" (id (one-or-more not-newline)) "]")
+            (optional "\n")
+            (message
+             (one-or-more " ") (one-or-more not-newline)
+             (zero-or-more "\n"
+                           (one-or-more " ")
+                           (one-or-more (not (any ?\n ?|)))))
+            line-end)
+   (error line-start (file-name) ":" line ":" column ":" (optional " error:")
+          (or (message (one-or-more not-newline))
+              (and "\n"
+                   (message
+                    (one-or-more " ") (one-or-more not-newline)
+                    (zero-or-more "\n"
+                                  (one-or-more " ")
+                                  (one-or-more (not (any ?\n ?|)))))))
+          line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors (flycheck-dedent-error-messages errors)))
+  :modes (haskell-mode literate-haskell-mode)
+  :next-checkers ((warning . haskell-hlint))
+  :working-directory flycheck-haskell--find-default-directory)
+
+(flycheck-def-config-file-var flycheck-hlintrc haskell-hlint "HLint.hs"
+  :safe #'stringp)
+
+(flycheck-def-args-var flycheck-hlint-args haskell-hlint
+  :package-version '(flycheck . "0.25"))
+
+(flycheck-def-option-var flycheck-hlint-language-extensions
+    nil haskell-hlint
+  "Extensions list to enable for hlint.
+
+The value of this variable is a list of strings, where each
+string is a name of extension to enable in
+hlint (e.g. \"QuasiQuotes\")."
+  :type '(repeat :tag "Extensions" (string :tag "Extension"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-def-option-var flycheck-hlint-ignore-rules
+    nil haskell-hlint
+  "Ignore rules list for hlint checks.
+
+The value of this variable is a list of strings, where each
+string is an ignore rule (e.g. \"Use fmap\")."
+  :type '(repeat :tag "Ignore rules" (string :tag "Ignore rule"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-def-option-var flycheck-hlint-hint-packages
+    nil haskell-hlint
+  "Hint packages to include for hlint checks.
+
+The value of this variable is a list of strings, where each
+string is a default hint package (e.g. (\"Generalise\"
+\"Default\" \"Dollar\"))."
+  :type '(repeat :tag "Hint packages" (string :tag "Hint package"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-define-checker haskell-hlint
+  "A Haskell style checker using hlint.
+
+See URL `https://github.com/ndmitchell/hlint'."
+  :command ("hlint"
+            (option-list "-X" flycheck-hlint-language-extensions concat)
+            (option-list "-i=" flycheck-hlint-ignore-rules concat)
+            (option-list "-h" flycheck-hlint-hint-packages concat)
+            (config-file "-h" flycheck-hlintrc)
+            (eval flycheck-hlint-args)
+            source-inplace)
+  :error-patterns
+  ((info line-start
+         (file-name) ":" line ":" column
+         ": Suggestion: "
+         (message (one-or-more (and (one-or-more (not (any ?\n))) ?\n)))
+         line-end)
+   (warning line-start
+            (file-name) ":" line ":" column
+            ": Warning: "
+            (message (one-or-more (and (one-or-more (not (any ?\n))) ?\n)))
+            line-end)
+   (error line-start
+          (file-name) ":" line ":" column
+          ": Error: "
+          (message (one-or-more (and (one-or-more (not (any ?\n))) ?\n)))
+          line-end))
+  :modes (haskell-mode literate-haskell-mode))
+
+(flycheck-def-config-file-var flycheck-tidyrc html-tidy ".tidyrc"
+  :safe #'stringp)
+
+(flycheck-define-checker html-tidy
+  "A HTML syntax and style checker using Tidy.
+
+See URL `https://github.com/htacg/tidy-html5'."
+  :command ("tidy" (config-file "-config" flycheck-tidyrc)
+            "-lang" "en"
+            "-e" "-q")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          "line " line
+          " column " column
+          " - Error: " (message) line-end)
+   (warning line-start
+            "line " line
+            " column " column
+            " - Warning: " (message) line-end))
+  :modes (html-mode mhtml-mode nxhtml-mode))
+
+(flycheck-def-config-file-var flycheck-jshintrc javascript-jshint ".jshintrc"
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-jshint-extract-javascript nil
+                         javascript-jshint
+  "Whether jshint should extract Javascript from HTML.
+
+If nil no extract rule is given to jshint.  If `auto' only
+extract Javascript if a HTML file is detected.  If `always' or
+`never' extract Javascript always or never respectively.
+
+Refer to the jshint manual at the URL
+`http://jshint.com/docs/cli/#flags' for more information."
+  :type
+  '(choice (const :tag "No extraction rule" nil)
+           (const :tag "Try to extract Javascript when detecting HTML files"
+                  auto)
+           (const :tag "Always try to extract Javascript" always)
+           (const :tag "Never try to extract Javascript" never))
+  :safe #'symbolp
+  :package-version '(flycheck . "26"))
+
+(flycheck-define-checker javascript-jshint
+  "A Javascript syntax and style checker using jshint.
+
+See URL `http://www.jshint.com'."
+  :command ("jshint" "--reporter=checkstyle"
+            "--filename" source-original
+            (config-file "--config" flycheck-jshintrc)
+            (option "--extract=" flycheck-jshint-extract-javascript
+                    concat flycheck-option-symbol)
+            "-")
+  :standard-input t
+  :error-parser flycheck-parse-checkstyle
+  :error-filter
+  (lambda (errors)
+    (flycheck-remove-error-file-names
+     "stdin" (flycheck-dequalify-error-ids errors)))
+  :modes (js-mode js2-mode js3-mode rjsx-mode))
+
+(flycheck-def-args-var flycheck-eslint-args javascript-eslint
+  :package-version '(flycheck . "32"))
+
+(flycheck-def-option-var flycheck-eslint-rules-directories nil javascript-eslint
+  "A list of directories with custom rules for ESLint.
+
+The value of this variable is a list of strings, where each
+string is a directory with custom rules for ESLint.
+
+Refer to the ESLint manual at URL
+`http://eslint.org/docs/user-guide/command-line-interface#--rulesdir'
+for more information about the custom directories."
+  :type '(repeat (directory :tag "Custom rules directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "29"))
+
+(defun flycheck-eslint-config-exists-p ()
+  "Whether there is a valid eslint config for the current buffer."
+  (let* ((executable (flycheck-find-checker-executable 'javascript-eslint))
+         (exitcode (and executable (call-process executable nil nil nil
+                                                 "--print-config" "."))))
+    (eq exitcode 0)))
+
+(defun flycheck-parse-eslint (output checker buffer)
+  "Parse ESLint errors/warnings from JSON OUTPUT.
+
+CHECKER and BUFFER denote the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `https://eslint.org' for more information about ESLint."
+  (mapcar (lambda (err)
+            (let-alist err
+              (flycheck-error-new-at
+               .line
+               .column
+               (pcase .severity
+                 (2 'error)
+                 (1 'warning)
+                 (_ 'warning))
+               .message
+               :id .ruleId
+               :checker checker
+               :buffer buffer
+               :filename (buffer-file-name buffer))))
+          (let-alist (caar (flycheck-parse-json output))
+            .messages)))
+
+(defun flycheck-eslint--find-working-directory (_checker)
+  "Look for a working directory to run ESLint CHECKER in.
+
+This will be the directory that contains the `node_modules'
+directory.  If no such directory is found in the directory
+hierarchy, it looks first for `.eslintignore' and then for
+`.eslintrc' files to detect the project root."
+  (let* ((regex-config (concat "\\`\\.eslintrc"
+                               "\\(\\.\\(js\\|ya?ml\\|json\\)\\)?\\'")))
+    (when buffer-file-name
+      (or (locate-dominating-file buffer-file-name "node_modules")
+          (locate-dominating-file buffer-file-name ".eslintignore")
+          (locate-dominating-file
+           (file-name-directory buffer-file-name)
+           (lambda (directory)
+             (> (length (directory-files directory nil regex-config t)) 0)))))))
+
+(flycheck-define-checker javascript-eslint
+  "A Javascript syntax and style checker using eslint.
+
+See URL `https://eslint.org/'."
+  :command ("eslint" "--format=json"
+            (option-list "--rulesdir" flycheck-eslint-rules-directories)
+            (eval flycheck-eslint-args)
+            "--stdin" "--stdin-filename" source-original)
+  :standard-input t
+  :error-parser flycheck-parse-eslint
+  :enabled (lambda () (flycheck-eslint-config-exists-p))
+  :modes (js-mode js-jsx-mode js2-mode js2-jsx-mode js3-mode rjsx-mode)
+  :working-directory flycheck-eslint--find-working-directory
+  :verify
+  (lambda (_)
+    (let* ((default-directory
+             (flycheck-compute-working-directory 'javascript-eslint))
+           (have-config (flycheck-eslint-config-exists-p)))
+      (list
+       (flycheck-verification-result-new
+        :label "config file"
+        :message (if have-config "found" "missing or incorrect")
+        :face (if have-config 'success '(bold error)))))))
+
+(flycheck-define-checker javascript-standard
+  "A Javascript code and style checker for the (Semi-)Standard Style.
+
+This checker works with `standard' and `semistandard', defaulting
+to the former.  To use it with the latter, set
+`flycheck-javascript-standard-executable' to `semistandard'.
+
+See URL `https://github.com/standard/standard' and URL
+`https://github.com/Flet/semistandard'."
+  :command ("standard" "--stdin")
+  :standard-input t
+  :error-patterns
+  ((error line-start "  <text>:" line ":" column ":" (message) line-end))
+  :modes (js-mode js-jsx-mode js2-mode js2-jsx-mode js3-mode rjsx-mode))
+
+(flycheck-define-checker json-jsonlint
+  "A JSON syntax and style checker using jsonlint.
+
+See URL `https://github.com/zaach/jsonlint'."
+  ;; We can't use standard input for jsonlint, because it doesn't output errors
+  ;; anymore when using -c -q with standard input :/
+  :command ("jsonlint" "-c" "-q" source)
+  :error-patterns
+  ((error line-start
+          (file-name)
+          ": line " line
+          ", col " column ", "
+          (message) line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors (flycheck-increment-error-columns errors)))
+  :modes json-mode)
+
+(flycheck-define-checker json-python-json
+  "A JSON syntax checker using Python json.tool module.
+
+See URL `https://docs.python.org/3.5/library/json.html#command-line-interface'."
+  :command ("python" "-m" "json.tool" source
+            ;; Send the pretty-printed output to the null device
+            null-device)
+  :error-patterns
+  ((error line-start
+          (message) ": line " line " column " column
+          ;; Ignore the rest of the line which shows the char position.
+          (one-or-more not-newline)
+          line-end))
+  :modes json-mode
+  ;; The JSON parser chokes if the buffer is empty and has no JSON inside
+  :predicate (lambda () (not (flycheck-buffer-empty-p))))
+
+(flycheck-define-checker jsonnet
+  "A Jsonnet syntax checker using the jsonnet binary.
+
+See URL `https://jsonnet.org'."
+  :command ("jsonnet" source-inplace)
+  :error-patterns
+  ((error line-start "STATIC ERROR: " (file-name) ":" line ":" column
+          (zero-or-one (group "-" (one-or-more digit))) ": "
+          (message) line-end)
+   (error line-start "RUNTIME ERROR: " (message) "\n"
+          (one-or-more space) (file-name) ":" (zero-or-one "(")
+          line ":" column (zero-or-more not-newline) line-end))
+  :modes jsonnet-mode)
+
+(flycheck-define-checker less
+  "A LESS syntax checker using lessc.
+
+Requires lessc 1.4 or newer.
+
+See URL `http://lesscss.org'."
+  :command ("lessc" "--lint" "--no-color"
+            "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start (one-or-more word) ":"
+          (message)
+          " in - on line " line
+          ", column " column ":"
+          line-end))
+  :modes less-css-mode)
+
+(flycheck-define-checker less-stylelint
+  "A LESS syntax and style checker using stylelint.
+
+See URL `http://stylelint.io/'."
+  :command ("stylelint"
+            (eval flycheck-stylelint-args)
+            "--syntax" "less"
+            (option-flag "--quiet" flycheck-stylelint-quiet)
+            (config-file "--config" flycheck-stylelintrc))
+  :standard-input t
+  :error-parser flycheck-parse-stylelint
+  :modes (less-css-mode))
+
+(flycheck-define-checker llvm-llc
+  "Flycheck LLVM IR checker using llc.
+
+See URL `http://llvm.org/docs/CommandGuide/llc.html'."
+  :command ("llc" "-o" null-device source)
+  :error-patterns
+  ((error line-start
+          ;; llc prints the executable path
+          (zero-or-one (minimal-match (one-or-more not-newline)) ": ")
+          (file-name) ":" line ":" column ": error: " (message)
+          line-end))
+  :error-filter
+  (lambda (errors)
+    ;; sanitize errors occurring in inline assembly
+    (flycheck-sanitize-errors
+     (flycheck-remove-error-file-names "<inline asm>" errors)))
+  :modes llvm-mode)
+
+(flycheck-def-config-file-var flycheck-luacheckrc lua-luacheck ".luacheckrc"
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-luacheck-standards nil lua-luacheck
+  "The standards to use in luacheck.
+
+The value of this variable is either a list of strings denoting
+the standards to use, or nil to pass nothing to luacheck.  When
+non-nil, pass the standards via one or more `--std' options."
+  :type '(choice (const :tag "Default" nil)
+                 (repeat :tag "Custom standards"
+                         (string :tag "Standard name")))
+  :safe #'flycheck-string-list-p)
+(make-variable-buffer-local 'flycheck-luacheck-standards)
+
+(flycheck-define-checker lua-luacheck
+  "A Lua syntax checker using luacheck.
+
+See URL `https://github.com/mpeterv/luacheck'."
+  :command ("luacheck"
+            "--formatter" "plain"
+            "--codes"                   ; Show warning codes
+            "--no-color"
+            (option-list "--std" flycheck-luacheck-standards)
+            (config-file "--config" flycheck-luacheckrc)
+            "--filename" source-original
+            ;; Read from standard input
+            "-")
+  :standard-input t
+  :error-patterns
+  ((warning line-start
+            (optional (file-name))
+            ":" line ":" column
+            ": (" (id "W" (one-or-more digit)) ") "
+            (message) line-end)
+   (error line-start
+          (optional (file-name))
+          ":" line ":" column ":"
+          ;; `luacheck' before 0.11.0 did not output codes for errors, hence
+          ;; the ID is optional here
+          (optional " (" (id "E" (one-or-more digit)) ") ")
+          (message) line-end))
+  :modes lua-mode)
+
+(flycheck-define-checker lua
+  "A Lua syntax checker using the Lua compiler.
+
+See URL `http://www.lua.org/'."
+  :command ("luac" "-p" "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          ;; Skip the name of the luac executable.
+          (minimal-match (zero-or-more not-newline))
+          ": stdin:" line ": " (message) line-end))
+  :modes lua-mode)
+
+(flycheck-def-option-var flycheck-perl-include-path nil perl
+  "A list of include directories for Perl.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of Perl.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-def-option-var flycheck-perl-module-list nil perl
+  "A list of modules to use for Perl.
+
+The value of this variable is a list of strings, where each
+string is a module to 'use' in Perl."
+  :type '(repeat :tag "Module")
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "32"))
+
+(flycheck-define-checker perl
+  "A Perl syntax checker using the Perl interpreter.
+
+See URL `https://www.perl.org'."
+  :command ("perl" "-w" "-c"
+            (option-list "-I" flycheck-perl-include-path)
+            (option-list "-M" flycheck-perl-module-list concat))
+  :standard-input t
+  :error-patterns
+  ((error line-start (minimal-match (message))
+          " at - line " line
+          (or "." (and ", " (zero-or-more not-newline))) line-end))
+  :modes (perl-mode cperl-mode)
+  :next-checkers (perl-perlcritic))
+
+(flycheck-def-option-var flycheck-perlcritic-severity nil perl-perlcritic
+  "The message severity for Perl Critic.
+
+The value of this variable is a severity level as integer, for
+the `--severity' option to Perl Critic."
+  :type '(integer :tag "Severity level")
+  :safe #'integerp
+  :package-version '(flycheck . "0.18"))
+
+(flycheck-def-config-file-var flycheck-perlcriticrc perl-perlcritic
+                              ".perlcriticrc"
+  :safe #'stringp
+  :package-version '(flycheck . "26"))
+
+(flycheck-define-checker perl-perlcritic
+  "A Perl syntax checker using Perl::Critic.
+
+See URL `https://metacpan.org/pod/Perl::Critic'."
+  :command ("perlcritic" "--no-color" "--verbose" "%f/%l/%c/%s/%p/%m (%e)\n"
+            (config-file "--profile" flycheck-perlcriticrc)
+            (option "--severity" flycheck-perlcritic-severity nil
+                    flycheck-option-int))
+  :standard-input t
+  :error-patterns
+  ((info line-start
+         "STDIN/" line "/" column "/" (any "1") "/"
+         (id (one-or-more (not (any "/")))) "/" (message)
+         line-end)
+   (warning line-start
+            "STDIN/" line "/" column "/" (any "234") "/"
+            (id (one-or-more (not (any "/")))) "/" (message)
+            line-end)
+   (error line-start
+          "STDIN/" line "/" column "/" (any "5") "/"
+          (id (one-or-more (not (any "/")))) "/" (message)
+          line-end))
+  :modes (cperl-mode perl-mode))
+
+(flycheck-define-checker php
+  "A PHP syntax checker using the PHP command line interpreter.
+
+See URL `http://php.net/manual/en/features.commandline.php'."
+  :command ("php" "-l" "-d" "error_reporting=E_ALL" "-d" "display_errors=1"
+            "-d" "log_errors=0" source)
+  :error-patterns
+  ((error line-start (or "Parse" "Fatal" "syntax") " error" (any ":" ",") " "
+          (message) " in " (file-name) " on line " line line-end))
+  :modes (php-mode php+-mode)
+  :next-checkers ((warning . php-phpmd)
+                  (warning . php-phpcs)))
+
+(flycheck-def-option-var flycheck-phpmd-rulesets
+    '("cleancode" "codesize" "controversial" "design" "naming" "unusedcode")
+    php-phpmd
+  "The rule sets for PHP Mess Detector.
+
+Set default rule sets and custom rule set files.
+
+See section \"Using multiple rule sets\" in the PHP Mess Detector
+manual at URL `https://phpmd.org/documentation/index.html'."
+  :type '(repeat :tag "rule sets"
+                 (string :tag "A filename or rule set"))
+  :safe #'flycheck-string-list-p)
+
+(flycheck-define-checker php-phpmd
+  "A PHP style checker using PHP Mess Detector.
+
+See URL `https://phpmd.org/'."
+  :command ("phpmd" source "xml"
+            (eval (flycheck-option-comma-separated-list
+                   flycheck-phpmd-rulesets)))
+  :error-parser flycheck-parse-phpmd
+  :modes (php-mode php+-mode)
+  :next-checkers (php-phpcs))
+
+(flycheck-def-option-var flycheck-phpcs-standard nil php-phpcs
+  "The coding standard for PHP CodeSniffer.
+
+When nil, use the default standard from the global PHP
+CodeSniffer configuration.  When set to a string, pass the string
+to PHP CodeSniffer which will interpret it as name as a standard,
+or as path to a standard specification."
+  :type '(choice (const :tag "Default standard" nil)
+                 (string :tag "Standard name or file"))
+  :safe #'stringp)
+
+(flycheck-define-checker php-phpcs
+  "A PHP style checker using PHP Code Sniffer.
+
+Needs PHP Code Sniffer 2.6 or newer.
+
+See URL `http://pear.php.net/package/PHP_CodeSniffer/'."
+  :command ("phpcs" "--report=checkstyle"
+            ;; Use -q flag to force quiet mode
+            ;; Quiet mode prevents errors from extra output when phpcs has
+            ;; been configured with show_progress enabled
+            "-q"
+            (option "--standard=" flycheck-phpcs-standard concat)
+            ;; Pass original file name to phpcs.  We need to concat explicitly
+            ;; here, because phpcs really insists to get option and argument as
+            ;; a single command line argument :|
+            (eval (when (buffer-file-name)
+                    (concat "--stdin-path=" (buffer-file-name))))
+            ;; Read from standard input
+            "-")
+  :standard-input t
+  :error-parser flycheck-parse-checkstyle
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors
+     (flycheck-remove-error-file-names "STDIN" errors)))
+  :modes (php-mode php+-mode)
+  ;; phpcs seems to choke on empty standard input, hence skip phpcs if the
+  ;; buffer is empty, see https://github.com/flycheck/flycheck/issues/907
+  :predicate (lambda () (not (flycheck-buffer-empty-p))))
+
+(flycheck-define-checker processing
+  "Processing command line tool.
+
+See https://github.com/processing/processing/wiki/Command-Line"
+  :command ("processing-java" "--force"
+            ;; Don't change the order of these arguments, processing is pretty
+            ;; picky
+            (eval (concat "--sketch=" (file-name-directory (buffer-file-name))))
+            (eval (concat "--output=" (flycheck-temp-dir-system)))
+            "--build")
+  :error-patterns
+  ((error line-start (file-name) ":" line ":" column
+          (zero-or-more (or digit ":")) (message) line-end))
+  :modes processing-mode
+  ;; This syntax checker needs a file name
+  :predicate (lambda () (buffer-file-name)))
+
+(defun flycheck-proselint-parse-errors (output checker buffer)
+  "Parse proselint json output errors from OUTPUT.
+
+CHECKER and BUFFER denoted the CHECKER that returned OUTPUT and
+the BUFFER that was checked respectively.
+
+See URL `http://proselint.com/' for more information about proselint."
+  (mapcar (lambda (err)
+            (let-alist err
+              (flycheck-error-new-at
+               .line
+               .column
+               (pcase .severity
+                 (`"suggestion" 'info)
+                 (`"warning"    'warning)
+                 (`"error"      'error)
+                 ;; Default to error
+                 (_             'error))
+               .message
+               :id .check
+               :buffer buffer
+               :checker checker)))
+          (let-alist (car (flycheck-parse-json output))
+            .data.errors)))
+
+(flycheck-define-checker proselint
+  "Flycheck checker using Proselint.
+
+See URL `http://proselint.com/'."
+  :command ("proselint" "--json" "-")
+  :standard-input t
+  :error-parser flycheck-proselint-parse-errors
+  :modes (text-mode markdown-mode gfm-mode message-mode))
+
+(flycheck-define-checker protobuf-protoc
+  "A protobuf syntax checker using the protoc compiler.
+
+See URL `https://developers.google.com/protocol-buffers/'."
+  :command ("protoc" "--error_format" "gcc"
+            (eval (concat "--java_out=" (flycheck-temp-dir-system)))
+            ;; Add the file directory of protobuf path to resolve import
+            ;; directives
+            (eval (concat "--proto_path="
+                          (file-name-directory (buffer-file-name))))
+            source-inplace)
+  :error-patterns
+  ((info line-start (file-name) ":" line ":" column
+         ": note: " (message) line-end)
+   (error line-start (file-name) ":" line ":" column
+          ": " (message) line-end)
+   (error line-start
+          (message "In file included from") " " (file-name) ":" line ":"
+          column ":" line-end))
+  :modes protobuf-mode
+  :predicate (lambda () (buffer-file-name)))
+
+(flycheck-define-checker pug
+  "A Pug syntax checker using the pug compiler.
+
+See URL `https://pugjs.org/'."
+  :command ("pug" "-p" (eval (expand-file-name (buffer-file-name))))
+  :standard-input t
+  :error-patterns
+  ;; errors with includes/extends (e.g. missing files)
+  ((error "Error: " (message) (zero-or-more not-newline) "\n"
+          (zero-or-more not-newline) "at "
+          (zero-or-more not-newline) " line " line)
+   ;; syntax/runtime errors (e.g. type errors, bad indentation, etc.)
+   (error line-start
+          (optional "Type") "Error: "  (file-name) ":"
+          line (optional ":" column)
+          (zero-or-more not-newline) "\n"
+          (one-or-more (or (zero-or-more not-newline) "|"
+                           (zero-or-more not-newline) "\n")
+                       (zero-or-more "-")  (zero-or-more not-newline) "|"
+                       (zero-or-more not-newline) "\n")
+          (zero-or-more not-newline) "\n"
+          (one-or-more
+           (zero-or-more not-newline) "|"
+           (zero-or-more not-newline) "\n")
+          (zero-or-more not-newline) "\n"
+          (message)
+          line-end))
+  :modes pug-mode)
+
+(flycheck-define-checker puppet-parser
+  "A Puppet DSL syntax checker using puppet's own parser.
+
+See URL `https://puppet.com/'."
+  :command ("puppet" "parser" "validate" "--color=false")
+  :standard-input t
+  :error-patterns
+  (
+   ;; Patterns for Puppet 4
+   (error line-start "Error: Could not parse for environment "
+          (one-or-more (in "a-z" "0-9" "_")) ":"
+          (message) "(line: " line ", column: " column ")" line-end)
+   ;; Errors from Puppet < 4
+   (error line-start "Error: Could not parse for environment "
+          (one-or-more (in "a-z" "0-9" "_")) ":"
+          (message (minimal-match (one-or-more anything)))
+          " at line " line line-end)
+   (error line-start
+          ;; Skip over the path of the Puppet executable
+          (minimal-match (zero-or-more not-newline))
+          ": Could not parse for environment " (one-or-more word)
+          ": " (message (minimal-match (zero-or-more anything)))
+          " at " (file-name "/" (zero-or-more not-newline)) ":" line line-end))
+  :modes puppet-mode
+  :next-checkers ((warning . puppet-lint)))
+
+(flycheck-def-config-file-var flycheck-puppet-lint-rc puppet-lint
+                              ".puppet-lint.rc"
+  :safe #'stringp
+  :package-version '(flycheck . "26"))
+
+(flycheck-def-option-var flycheck-puppet-lint-disabled-checks nil puppet-lint
+  "Disabled checkers for `puppet-lint'.
+
+The value of this variable is a list of strings, where each
+string is the name of a check to disable (e.g. \"80chars\" or
+\"double_quoted_strings\").
+
+See URL `http://puppet-lint.com/checks/' for a list of all checks
+and their names."
+  :type '(repeat (string :tag "Check Name"))
+  :package-version '(flycheck . "26"))
+
+(defun flycheck-puppet-lint-disabled-arg-name (check)
+  "Create an argument to disable a puppetlint CHECK."
+  (concat "--no-" check "-check"))
+
+(flycheck-define-checker puppet-lint
+  "A Puppet DSL style checker using puppet-lint.
+
+See URL `http://puppet-lint.com/'."
+  ;; We must check the original file, because Puppetlint is quite picky on the
+  ;; names of files and there place in the directory structure, to comply with
+  ;; Puppet's autoload directory layout.  For instance, a class foo::bar is
+  ;; required to be in a file foo/bar.pp.  Any other place, such as a Flycheck
+  ;; temporary file will cause an error.
+  :command ("puppet-lint"
+            (config-file "--config" flycheck-puppet-lint-rc)
+            "--log-format"
+            "%{path}:%{line}:%{kind}: %{message} (%{check})"
+            (option-list "" flycheck-puppet-lint-disabled-checks concat
+                         flycheck-puppet-lint-disabled-arg-name)
+            source-original)
+  :error-patterns
+  ((warning line-start (file-name) ":" line ":warning: " (message) line-end)
+   (error line-start (file-name) ":" line ":error: " (message) line-end))
+  :modes puppet-mode
+  ;; Since we check the original file, we can only use this syntax checker if
+  ;; the buffer is actually linked to a file, and if it is not modified.
+  :predicate flycheck-buffer-saved-p)
+
+(defun flycheck-python-find-module (checker module)
+  "Check if a Python MODULE is available.
+CHECKER's executable is assumed to be a Python REPL."
+  (-when-let* ((py (flycheck-find-checker-executable checker))
+               (script (concat "import sys; sys.path.pop(0);"
+                               (format "import %s; print(%s.__file__)"
+                                       module module))))
+    (with-temp-buffer
+      (and (eq (ignore-errors (call-process py nil t nil "-c" script)) 0)
+           (string-trim (buffer-string))))))
+
+(defun flycheck-python-needs-module-p (checker)
+  "Determines whether CHECKER needs to be invoked through Python.
+Previous versions of Flycheck called pylint and flake8 directly;
+this check ensures that we don't break existing code."
+  (not (string-match-p (rx (or "pylint" "flake8")
+                           (or "-script.pyw" ".exe" ".bat" "")
+                           eos)
+                       (flycheck-checker-executable checker))))
+
+(defun flycheck-python-verify-module (checker module)
+  "Verify that a Python MODULE is available.
+Return nil if CHECKER's executable is not a Python REPL.  This
+function's is suitable for a checker's :verify."
+  (when (flycheck-python-needs-module-p checker)
+    (let ((mod-path (flycheck-python-find-module checker module)))
+      (list (flycheck-verification-result-new
+             :label (format "`%s' module" module)
+             :message (if mod-path (format "Found at %S" mod-path) "Missing")
+             :face (if mod-path 'success '(bold error)))))))
+
+(defun flycheck-python-module-args (checker module-name)
+  "Compute arguments to pass to CHECKER's executable to run MODULE-NAME.
+Return nil if CHECKER's executable is not a Python REPL.
+Otherwise, return a list starting with -c (-m is not enough
+because it adds the current directory to Python's path)."
+  (when (flycheck-python-needs-module-p checker)
+    `("-c" ,(concat "import sys,runpy;sys.path.pop(0);"
+                    (format "runpy.run_module(%S)" module-name)))))
+
+(flycheck-def-config-file-var flycheck-flake8rc python-flake8 ".flake8rc"
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-flake8-error-level-alist
+    '(("^E9.*$"  . error)               ; Syntax errors from pep8
+      ("^F82.*$" . error)               ; undefined variables from pyflakes
+      ("^F83.*$" . error)               ; Duplicate arguments from flake8
+      ("^D.*$"   . info)                ; Docstring issues from flake8-pep257
+      ("^N.*$"   . info)                ; Naming issues from pep8-naming
+      )
+    python-flake8
+  "An alist mapping flake8 error IDs to Flycheck error levels.
+
+Each item in this list is a cons cell `(PATTERN . LEVEL)' where
+PATTERN is a regular expression matched against the error ID, and
+LEVEL is a Flycheck error level symbol.
+
+Each PATTERN is matched in the order of appearance in this list
+against the error ID.  If it matches the ID, the level of the
+corresponding error is set to LEVEL.  An error that is not
+matched by any PATTERN defaults to warning level.
+
+The default value of this option matches errors from flake8
+itself and from the following flake8 plugins:
+
+- pep8-naming
+- flake8-pep257
+
+You may add your own mappings to this option in order to support
+further flake8 plugins."
+  :type '(repeat (cons (regexp :tag "Error ID pattern")
+                       (symbol :tag "Error level")))
+  :package-version '(flycheck . "0.22"))
+
+(flycheck-def-option-var flycheck-flake8-maximum-complexity nil python-flake8
+  "The maximum McCabe complexity of methods.
+
+If nil, do not check the complexity of methods.  If set to an
+integer, report any complexity greater than the value of this
+variable as warning.
+
+If set to an integer, this variable overrules any similar setting
+in the configuration file denoted by `flycheck-flake8rc'."
+  :type '(choice (const :tag "Do not check McCabe complexity" nil)
+                 (integer :tag "Maximum complexity"))
+  :safe #'integerp)
+
+(flycheck-def-option-var flycheck-flake8-maximum-line-length nil python-flake8
+  "The maximum length of lines.
+
+If set to an integer, the value of this variable denotes the
+maximum length of lines, overruling any similar setting in the
+configuration file denoted by `flycheck-flake8rc'.  An error will
+be reported for any line longer than the value of this variable.
+
+If set to nil, use the maximum line length from the configuration
+file denoted by `flycheck-flake8rc', or the PEP 8 recommendation
+of 79 characters if there is no configuration with this setting."
+  :type '(choice (const :tag "Default value")
+                 (integer :tag "Maximum line length in characters"))
+  :safe #'integerp)
+
+(defun flycheck-flake8-fix-error-level (err)
+  "Fix the error level of ERR.
+
+Update the error level of ERR according to
+`flycheck-flake8-error-level-alist'."
+  (pcase-dolist (`(,pattern . ,level) flycheck-flake8-error-level-alist)
+    (when (string-match-p pattern (flycheck-error-id err))
+      (setf (flycheck-error-level err) level)))
+  err)
+
+(flycheck-define-checker python-flake8
+  "A Python syntax and style checker using Flake8.
+
+Requires Flake8 3.0 or newer. See URL
+`https://flake8.readthedocs.io/'."
+  ;; Not calling flake8 directly makes it easier to switch between different
+  ;; Python versions; see https://github.com/flycheck/flycheck/issues/1055.
+  :command ("python"
+            (eval (flycheck-python-module-args 'python-flake8 "flake8"))
+            "--format=default"
+            (config-file "--config" flycheck-flake8rc)
+            (option "--max-complexity" flycheck-flake8-maximum-complexity nil
+                    flycheck-option-int)
+            (option "--max-line-length" flycheck-flake8-maximum-line-length nil
+                    flycheck-option-int)
+            "-")
+  :standard-input t
+  :error-filter (lambda (errors)
+                  (let ((errors (flycheck-sanitize-errors errors)))
+                    (seq-map #'flycheck-flake8-fix-error-level errors)))
+  :error-patterns
+  ((warning line-start
+            "stdin:" line ":" (optional column ":") " "
+            (id (one-or-more (any alpha)) (one-or-more digit)) " "
+            (message (one-or-more not-newline))
+            line-end))
+  :enabled (lambda ()
+             (or (not (flycheck-python-needs-module-p 'python-flake8))
+                 (flycheck-python-find-module 'python-flake8 "flake8")))
+  :verify (lambda (_) (flycheck-python-verify-module 'python-flake8 "flake8"))
+  :modes python-mode)
+
+(flycheck-def-config-file-var flycheck-pylintrc python-pylint ".pylintrc"
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-pylint-use-symbolic-id t python-pylint
+  "Whether to use pylint message symbols or message codes.
+
+A pylint message has both an opaque identifying code (such as `F0401') and a
+more meaningful symbolic code (such as `import-error').  This option governs
+which should be used and reported to the user."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.25"))
+
+(flycheck-define-checker python-pylint
+  "A Python syntax and style checker using Pylint.
+
+This syntax checker requires Pylint 1.0 or newer.
+
+See URL `https://www.pylint.org/'."
+  ;; --reports=n disables the scoring report.
+  ;; Not calling pylint directly makes it easier to switch between different
+  ;; Python versions; see https://github.com/flycheck/flycheck/issues/1055.
+  :command ("python"
+            (eval (flycheck-python-module-args 'python-pylint "pylint"))
+            "--reports=n"
+            "--output-format=text"
+            (eval (if flycheck-pylint-use-symbolic-id
+                      "--msg-template={path}:{line}:{column}:{C}:{symbol}:{msg}"
+                    "--msg-template={path}:{line}:{column}:{C}:{msg_id}:{msg}"))
+            (config-file "--rcfile=" flycheck-pylintrc concat)
+            ;; Need `source-inplace' for relative imports (e.g. `from .foo
+            ;; import bar'), see https://github.com/flycheck/flycheck/issues/280
+            source-inplace)
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors (flycheck-increment-error-columns errors)))
+  :error-patterns
+  ((error line-start (file-name) ":" line ":" column ":"
+          (or "E" "F") ":"
+          (id (one-or-more (not (any ":")))) ":"
+          (message) line-end)
+   (warning line-start (file-name) ":" line ":" column ":"
+            (or "W" "R") ":"
+            (id (one-or-more (not (any ":")))) ":"
+            (message) line-end)
+   (info line-start (file-name) ":" line ":" column ":"
+         (or "C" "I") ":"
+         (id (one-or-more (not (any ":")))) ":"
+         (message) line-end))
+  :enabled (lambda ()
+             (or (not (flycheck-python-needs-module-p 'python-pylint))
+                 (flycheck-python-find-module 'python-pylint "pylint")))
+  :verify (lambda (_) (flycheck-python-verify-module 'python-pylint "pylint"))
+  :modes python-mode)
+
+(flycheck-define-checker python-pycompile
+  "A Python syntax checker using Python's builtin compiler.
+
+See URL `https://docs.python.org/3.4/library/py_compile.html'."
+  :command ("python" "-m" "py_compile" source)
+  :error-patterns
+  ;; Python 2.7
+  ((error line-start "  File \"" (file-name) "\", line " line "\n"
+          (>= 2 (zero-or-more not-newline) "\n")
+          "SyntaxError: " (message) line-end)
+   (error line-start "Sorry: IndentationError: "
+          (message) "(" (file-name) ", line " line ")"
+          line-end)
+   ;; 2.6
+   (error line-start "SyntaxError: ('" (message (one-or-more (not (any "'"))))
+          "', ('" (file-name (one-or-more (not (any "'")))) "', "
+          line ", " column ", " (one-or-more not-newline) line-end))
+  :modes python-mode)
+
+(flycheck-def-config-file-var flycheck-python-mypy-ini python-mypy
+                              "mypy.ini"
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-python-mypy-cache-dir nil python-mypy
+  "Directory used to write .mypy_cache directories."
+  :safe #'stringp
+  :type '(choice
+          (const :tag "Write to the working directory" nil)
+          (const :tag "Never write .mypy_cache directories" null-device)
+          (string :tag "Path"))
+  :package-version '(flycheck . "32"))
+
+(flycheck-define-checker python-mypy
+  "Mypy syntax and type checker.  Requires mypy>=0.580.
+
+See URL `http://mypy-lang.org/'."
+  :command ("mypy"
+            (config-file "--config-file" flycheck-python-mypy-ini)
+            (option "--cache-dir" flycheck-python-mypy-cache-dir)
+            source-original)
+  :error-patterns
+  ((error line-start (file-name) ":" line ": error:" (message) line-end)
+   (warning line-start (file-name) ":" line ": warning:" (message) line-end))
+  :modes python-mode
+  ;; Ensure the file is saved, to work around
+  ;; https://github.com/python/mypy/issues/4746.
+  :predicate flycheck-buffer-saved-p
+  :next-checkers '(t . python-flake8))
+
+(flycheck-def-option-var flycheck-lintr-caching t r-lintr
+  "Whether to enable caching in lintr.
+
+By default, lintr caches all expressions in a file and re-checks
+only those that have changed.  Setting this option to nil
+disables caching in case there are problems."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-def-option-var flycheck-lintr-linters "default_linters" r-lintr
+  "Linters to use with lintr.
+
+The value of this variable is a string containing an R
+expression, which selects linters for lintr."
+  :type 'string
+  :risky t
+  :package-version '(flycheck . "0.23"))
+
+(defun flycheck-r-has-lintr (R)
+  "Whether R has installed the `lintr' library."
+  (with-temp-buffer
+    (let ((process-environment (append '("LC_ALL=C") process-environment)))
+      (call-process R nil t nil
+                    "--slave" "--restore" "--no-save" "-e"
+                    "library('lintr')")
+      (goto-char (point-min))
+      (not (re-search-forward "there is no package called 'lintr'"
+                              nil 'no-error)))))
+
+(flycheck-define-checker r-lintr
+  "An R style and syntax checker using the lintr package.
+
+See URL `https://github.com/jimhester/lintr'."
+  :command ("R" "--slave" "--restore" "--no-save" "-e"
+            (eval (concat
+                   "library(lintr);"
+                   "try(lint(commandArgs(TRUE)"
+                   ", cache=" (if flycheck-lintr-caching "TRUE" "FALSE")
+                   ", " flycheck-lintr-linters
+                   "))"))
+            "--args" source)
+  :error-patterns
+  ((info line-start (file-name) ":" line ":" column ": style: " (message)
+         line-end)
+   (warning line-start (file-name) ":" line ":" column ": warning: " (message)
+            line-end)
+   (error line-start (file-name) ":" line ":" column ": error: " (message)
+          line-end))
+  :modes ess-mode
+  :predicate
+  ;; Don't check ESS files which do not contain R, and make sure that lintr is
+  ;; actually available
+  (lambda ()
+    (and (equal ess-language "S")
+         (flycheck-r-has-lintr (flycheck-checker-executable 'r-lintr))))
+  :verify (lambda (checker)
+            (let ((has-lintr (flycheck-r-has-lintr
+                              (flycheck-checker-executable checker))))
+              (list
+               (flycheck-verification-result-new
+                :label "lintr library"
+                :message (if has-lintr "present" "missing")
+                :face (if has-lintr 'success '(bold error)))))))
+
+(defun flycheck-racket-has-expand-p (checker)
+  "Whether the executable of CHECKER provides the `expand' command."
+  (let ((raco (flycheck-find-checker-executable checker)))
+    (when raco
+      (with-temp-buffer
+        (call-process raco nil t nil "expand")
+        (goto-char (point-min))
+        (not (looking-at-p (rx bol (1+ not-newline)
+                               "Unrecognized command: expand"
+                               eol)))))))
+
+(flycheck-define-checker racket
+  "A Racket syntax checker with `raco expand'.
+
+The `compiler-lib' racket package is required for this syntax
+checker.
+
+See URL `https://racket-lang.org/'."
+  :command ("raco" "expand" source-inplace)
+  :predicate
+  (lambda ()
+    (and (or (not (eq major-mode 'scheme-mode))
+             ;; In `scheme-mode' we must check the current Scheme implementation
+             ;; being used
+             (and (boundp 'geiser-impl--implementation)
+                  (eq geiser-impl--implementation 'racket)))
+         (flycheck-racket-has-expand-p 'racket)))
+  :verify
+  (lambda (checker)
+    (let ((has-expand (flycheck-racket-has-expand-p checker))
+          (in-scheme-mode (eq major-mode 'scheme-mode))
+          (geiser-impl (bound-and-true-p geiser-impl--implementation)))
+      (list
+       (flycheck-verification-result-new
+        :label "compiler-lib package"
+        :message (if has-expand "present" "missing")
+        :face (if has-expand 'success '(bold error)))
+       (flycheck-verification-result-new
+        :label "Geiser Implementation"
+        :message (cond
+                  ((not in-scheme-mode) "Using Racket Mode")
+                  ((eq geiser-impl 'racket) "Racket")
+                  (geiser-impl (format "Other: %s" geiser-impl))
+                  (t "Geiser not active"))
+        :face (cond
+               ((or (not in-scheme-mode) (eq geiser-impl 'racket)) 'success)
+               (t '(bold error)))))))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors
+     (flycheck-increment-error-columns
+      (seq-remove
+       (lambda (err)
+         (string=
+          "/usr/share/racket/pkgs/compiler-lib/compiler/commands/expand.rkt"
+          (flycheck-error-filename err)))
+       errors))))
+  :error-patterns
+  ((error line-start (zero-or-more space)
+          (file-name) ":" line ":" column ":" (message) line-end))
+  :modes (racket-mode scheme-mode))
+
+(flycheck-define-checker rpm-rpmlint
+  "A RPM SPEC file syntax checker using rpmlint.
+
+See URL `https://sourceforge.net/projects/rpmlint/'."
+  :command ("rpmlint" source)
+  :error-patterns
+  ((error line-start
+          (file-name) ":" (optional line ":") " E: " (message)
+          line-end)
+   (warning line-start
+            (file-name) ":" (optional line ":") " W: " (message)
+            line-end))
+  :error-filter
+  ;; Add fake line numbers if they are missing in the lint output
+  (lambda (errors)
+    (dolist (err errors)
+      (unless (flycheck-error-line err)
+        (setf (flycheck-error-line err) 1)))
+    errors)
+  :error-explainer
+  (lambda (error)
+    (-when-let* ((error-message (flycheck-error-message error))
+                 (message-id (save-match-data
+                               (string-match "\\([^ ]+\\)" error-message)
+                               (match-string 1 error-message))))
+      (with-output-to-string
+        (call-process "rpmlint" nil standard-output nil "-I" message-id))))
+  :modes (sh-mode rpm-spec-mode)
+  :predicate (lambda () (or (not (eq major-mode 'sh-mode))
+                            ;; In `sh-mode', we need the proper shell
+                            (eq sh-shell 'rpm))))
+
+(flycheck-def-config-file-var flycheck-markdown-markdownlint-cli-config
+    markdown-markdownlint-cli nil
+  :safe #'stringp
+  :package-version '(flycheck . "32"))
+
+(flycheck-define-checker markdown-markdownlint-cli
+  "Markdown checker using markdownlint-cli.
+
+See URL `https://github.com/igorshubovych/markdownlint-cli'."
+  :command ("markdownlint"
+            (config-file "--config" flycheck-markdown-markdownlint-cli-config)
+            source)
+  :error-patterns
+  ((error line-start
+          (file-name) ": " line ": " (id (one-or-more (not (any space))))
+          " " (message) line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors
+     (flycheck-remove-error-file-names "(string)" errors)))
+  :modes (markdown-mode gfm-mode))
+
+(flycheck-def-option-var flycheck-markdown-mdl-rules nil markdown-mdl
+  "Rules to enable for mdl.
+
+The value of this variable is a list of strings each of which is
+the name of a rule to enable.
+
+By default all rules are enabled.
+
+See URL `https://git.io/vhi2t'."
+  :type '(repeat :tag "Enabled rules"
+                 (string :tag "rule name"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "27"))
+
+(flycheck-def-option-var flycheck-markdown-mdl-tags nil markdown-mdl
+  "Rule tags to enable for mdl.
+
+The value of this variable is a list of strings each of which is
+the name of a rule tag.  Only rules with these tags are enabled.
+
+By default all rules are enabled.
+
+See URL `https://git.io/vhi2t'."
+  :type '(repeat :tag "Enabled tags"
+                 (string :tag "tag name"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "27"))
+
+(flycheck-def-config-file-var flycheck-markdown-mdl-style markdown-mdl nil
+  :safe #'stringp
+  :package-version '(flycheck . "27"))
+
+(flycheck-define-checker markdown-mdl
+  "Markdown checker using mdl.
+
+See URL `https://github.com/markdownlint/markdownlint'."
+  :command ("mdl"
+            (config-file "--style" flycheck-markdown-mdl-style)
+            (option "--tags=" flycheck-markdown-mdl-rules concat
+                    flycheck-option-comma-separated-list)
+            (option "--rules=" flycheck-markdown-mdl-rules concat
+                    flycheck-option-comma-separated-list))
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (file-name) ":" line ": " (id (one-or-more alnum)) " " (message)
+          line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors
+     (flycheck-remove-error-file-names "(stdin)" errors)))
+  :modes (markdown-mode gfm-mode))
+
+(flycheck-define-checker nix
+  "Nix checker using nix-instantiate.
+
+See URL `https://nixos.org/nix/manual/#sec-nix-instantiate'."
+  :command ("nix-instantiate" "--parse" "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          "error: " (message) " at " (file-name) ":" line ":" column
+          line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors
+     (flycheck-remove-error-file-names "(string)" errors)))
+  :modes nix-mode)
+
+(defun flycheck-locate-sphinx-source-directory ()
+  "Locate the Sphinx source directory for the current buffer.
+
+Return the source directory, or nil, if the current buffer is not
+part of a Sphinx project."
+  (-when-let* ((filename (buffer-file-name))
+               (dir (locate-dominating-file filename "conf.py")))
+    (expand-file-name dir)))
+
+(flycheck-define-checker rst
+  "A ReStructuredText (RST) syntax checker using Docutils.
+
+See URL `http://docutils.sourceforge.net/'."
+  ;; We need to use source-inplace to properly resolve relative paths in
+  ;; include:: directives
+  :command ("rst2pseudoxml.py" "--report=2" "--halt=5"
+            ;; Read from standard input and throw output away
+            "-" null-device)
+  :standard-input t
+  :error-patterns
+  ((warning line-start "<stdin>:" line ": (WARNING/2) " (message) line-end)
+   (error line-start "<stdin>:" line
+          ": (" (or "ERROR/3" "SEVERE/4") ") "
+          (message) line-end))
+  :modes rst-mode)
+
+(flycheck-def-option-var flycheck-sphinx-warn-on-missing-references t rst-sphinx
+  "Whether to warn about missing references in Sphinx.
+
+When non-nil (the default), warn about all missing references in
+Sphinx via `-n'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.17"))
+
+(flycheck-define-checker rst-sphinx
+  "A ReStructuredText (RST) syntax checker using Sphinx.
+
+Requires Sphinx 1.2 or newer.  See URL `http://sphinx-doc.org'."
+  :command ("sphinx-build" "-b" "pseudoxml"
+            "-q" "-N"                   ; Reduced output and no colors
+            (option-flag "-n" flycheck-sphinx-warn-on-missing-references)
+            (eval (flycheck-locate-sphinx-source-directory))
+            temporary-directory         ; Redirect the output to a temporary
+                                        ; directory
+            source-original)            ; Sphinx needs the original document
+  :error-patterns
+  ((warning line-start (file-name) ":" line ": WARNING: " (message) line-end)
+   (error line-start
+          (file-name) ":" line
+          ": " (or "ERROR" "SEVERE") ": "
+          (message) line-end))
+  :modes rst-mode
+  :predicate (lambda () (and (flycheck-buffer-saved-p)
+                             (flycheck-locate-sphinx-source-directory))))
+
+(defun flycheck-ruby--find-project-root (_checker)
+  "Compute an appropriate working-directory for flycheck-ruby.
+
+This is either a parent directory containing a Gemfile, or nil."
+  (and
+   buffer-file-name
+   (locate-dominating-file buffer-file-name "Gemfile")))
+
+(flycheck-def-config-file-var flycheck-rubocoprc ruby-rubocop ".rubocop.yml"
+  :safe #'stringp)
+
+(flycheck-def-option-var flycheck-rubocop-lint-only nil ruby-rubocop
+  "Whether to only report code issues in Rubocop.
+
+When non-nil, only report code issues in Rubocop, via `--lint'.
+Otherwise report style issues as well."
+  :safe #'booleanp
+  :type 'boolean
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-define-checker ruby-rubocop
+  "A Ruby syntax and style checker using the RuboCop tool.
+
+You need at least RuboCop 0.34 for this syntax checker.
+
+See URL `http://batsov.com/rubocop/'."
+  :command ("rubocop"
+            "--display-cop-names"
+            "--force-exclusion"
+            "--format" "emacs"
+            ;; Explicitly disable caching to prevent Rubocop 0.35.1 and earlier
+            ;; from caching standard input.  Later versions of Rubocop
+            ;; automatically disable caching with --stdin, see
+            ;; https://github.com/flycheck/flycheck/issues/844 and
+            ;; https://github.com/bbatsov/rubocop/issues/2576
+            "--cache" "false"
+            (config-file "--config" flycheck-rubocoprc)
+            (option-flag "--lint" flycheck-rubocop-lint-only)
+            ;; Rubocop takes the original file name as argument when reading
+            ;; from standard input
+            "--stdin" source-original)
+  :standard-input t
+  :working-directory flycheck-ruby--find-project-root
+  :error-patterns
+  ((info line-start (file-name) ":" line ":" column ": C: "
+         (optional (id (one-or-more (not (any ":")))) ": ") (message) line-end)
+   (warning line-start (file-name) ":" line ":" column ": W: "
+            (optional (id (one-or-more (not (any ":")))) ": ") (message)
+            line-end)
+   (error line-start (file-name) ":" line ":" column ": " (or "E" "F") ": "
+          (optional (id (one-or-more (not (any ":")))) ": ") (message)
+          line-end))
+  :modes (enh-ruby-mode ruby-mode)
+  :next-checkers ((warning . ruby-reek)
+                  (warning . ruby-rubylint)))
+
+;; Default to `nil' to let Reek find its configuration file by itself
+(flycheck-def-config-file-var flycheck-reekrc ruby-reek nil
+  :safe #'string-or-null-p
+  :package-version '(flycheck . "30"))
+
+(flycheck-define-checker ruby-reek
+  "A Ruby smell checker using reek.
+
+See URL `https://github.com/troessner/reek'."
+  :command ("reek" "--format" "json"
+            (config-file "--config" flycheck-reekrc)
+            source)
+  :error-parser flycheck-parse-reek
+  :modes (enh-ruby-mode ruby-mode)
+  :next-checkers ((warning . ruby-rubylint)))
+
+;; Default to `nil' to let Rubylint find its configuration file by itself, and
+;; to maintain backwards compatibility with older Rubylint and Flycheck releases
+(flycheck-def-config-file-var flycheck-rubylintrc ruby-rubylint nil
+  :safe #'stringp)
+
+(flycheck-define-checker ruby-rubylint
+  "A Ruby syntax and code analysis checker using ruby-lint.
+
+Requires ruby-lint 2.0.2 or newer.  See URL
+`https://github.com/YorickPeterse/ruby-lint'."
+  :command ("ruby-lint" "--presenter=syntastic"
+            (config-file "--config" flycheck-rubylintrc)
+            source)
+  ;; Ruby Lint can't read from standard input
+  :error-patterns
+  ((info line-start
+         (file-name) ":I:" line ":" column ": " (message) line-end)
+   (warning line-start
+            (file-name) ":W:" line ":" column ": " (message) line-end)
+   (error line-start
+          (file-name) ":E:" line ":" column ": " (message) line-end))
+  :modes (enh-ruby-mode ruby-mode))
+
+(flycheck-define-checker ruby
+  "A Ruby syntax checker using the standard Ruby interpreter.
+
+Please note that the output of different Ruby versions and
+implementations varies wildly.  This syntax checker supports
+current versions of MRI and JRuby, but may break when used with
+other implementations or future versions of these
+implementations.
+
+Please consider using `ruby-rubocop' or `ruby-reek' instead.
+
+See URL `https://www.ruby-lang.org/'."
+  :command ("ruby" "-w" "-c")
+  :standard-input t
+  :error-patterns
+  ;; These patterns support output from JRuby, too, to deal with RVM or Rbenv
+  ((error line-start "SyntaxError in -:" line ": " (message) line-end)
+   (warning line-start "-:" line ":" (optional column ":")
+            " warning: " (message) line-end)
+   (error line-start "-:" line ": " (message) line-end))
+  :modes (enh-ruby-mode ruby-mode)
+  :next-checkers ((warning . ruby-rubylint)))
+
+(flycheck-define-checker ruby-jruby
+  "A Ruby syntax checker using the JRuby interpreter.
+
+This syntax checker is very primitive, and may break on future
+versions of JRuby.
+
+Please consider using `ruby-rubocop' or `ruby-rubylint' instead.
+
+See URL `http://jruby.org/'."
+  :command ("jruby" "-w" "-c")
+  :standard-input t
+  :error-patterns
+  ((error   line-start "SyntaxError in -:" line ": " (message) line-end)
+   (warning line-start "-:" line ": warning: " (message) line-end)
+   (error   line-start "-:" line ": "          (message) line-end))
+  :modes (enh-ruby-mode ruby-mode)
+  :next-checkers ((warning . ruby-rubylint)))
+
+(flycheck-def-args-var flycheck-cargo-check-args (rust-cargo)
+  :package-version '(flycheck . "32"))
+
+(flycheck-def-args-var flycheck-rust-args (rust)
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-def-option-var flycheck-rust-check-tests t (rust-cargo rust)
+  "Whether to check test code in Rust.
+
+For the `rust' checker: When non-nil, `rustc' is passed the
+`--test' flag, which will check any code marked with the
+`#[cfg(test)]' attribute and any functions marked with
+`#[test]'. Otherwise, `rustc' is not passed `--test' and test
+code will not be checked.  Skipping `--test' is necessary when
+using `#![no_std]', because compiling the test runner requires
+`std'.
+
+For the `rust-cargo' checker: When non-nil, calls `cargo test
+--no-run' instead of `cargo check'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '("flycheck" . "0.19"))
+
+(flycheck-def-option-var flycheck-rust-crate-root nil rust
+  "A path to the crate root for the current buffer.
+
+The value of this variable is either a string with the path to
+the crate root for the current buffer, or nil if the current buffer
+is a crate.  A relative path is relative to the current buffer.
+
+If this variable is non nil the current buffer will only be checked
+if it is not modified, i.e. after it has been saved."
+  :type 'string
+  :package-version '(flycheck . "0.20")
+  :safe #'stringp)
+(make-variable-buffer-local 'flycheck-rust-crate-root)
+
+(flycheck-def-option-var flycheck-rust-crate-type "lib" (rust-cargo rust)
+  "The type of the Rust Crate to check.
+
+For `rust-cargo', the value should be a string denoting the
+target type passed to Cargo.  See
+`flycheck-rust-valid-crate-type-p' for the list of allowed
+values.
+
+For `rust', the value should be a string denoting the crate type
+for the `--crate-type' flag of rustc."
+  :type '(choice (const :tag "nil (rust/rust-cargo)" nil)
+                 (const :tag "lib (rust/rust-cargo)" "lib")
+                 (const :tag "bin (rust/rust-cargo)" "bin")
+                 (const :tag "example (rust-cargo)" "example")
+                 (const :tag "test (rust-cargo)" "test")
+                 (const :tag "bench (rust-cargo)" "bench")
+                 (const :tag "rlib (rust)" "rlib")
+                 (const :tag "dylib (rust)" "dylib")
+                 (const :tag "cdylib (rust)" "cdylib")
+                 (const :tag "staticlib (rust)" "staticlib")
+                 (const :tag "metadata (rust)" "metadata"))
+  :safe #'stringp
+  :package-version '(flycheck . "0.20"))
+(make-variable-buffer-local 'flycheck-rust-crate-type)
+
+(flycheck-def-option-var flycheck-rust-binary-name nil rust-cargo
+  "The name of the binary to pass to `cargo check --CRATE-TYPE'.
+
+The value of this variable is a string denoting the name of the
+target to check: usually the name of the crate, or the name of
+one of the files under `src/bin', `tests', `examples' or
+`benches'.
+
+This always requires a non-nil value, unless
+`flycheck-rust-crate-type' is `lib' or nil, in which case it is
+ignored."
+  :type 'string
+  :safe #'stringp
+  :package-version '(flycheck . "28"))
+(make-variable-buffer-local 'flycheck-rust-binary-name)
+
+(flycheck-def-option-var flycheck-rust-library-path nil rust
+  "A list of library directories for Rust.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the library path of Rust.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Library directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.18"))
+
+(defun flycheck-rust-error-explainer (error)
+  "Return an explanation text for the given `flycheck-error' ERROR."
+  (-when-let (error-code (flycheck-error-id error))
+    (with-output-to-string
+      (call-process "rustc" nil standard-output nil "--explain" error-code))))
+
+(defun flycheck-rust-error-filter (errors)
+  "Filter ERRORS from rustc output that have no explanatory value."
+  (seq-remove
+   (lambda (err)
+     (or
+      ;; Macro errors emit a diagnostic in a phony file,
+      ;; e.g. "<println macros>".
+      (string-match-p
+       (rx "macros>" line-end)
+       (flycheck-error-filename err))
+      ;; Redundant message giving the number of failed errors
+      (string-match-p
+       (rx (or (: "aborting due to " (optional (one-or-more num) " ")
+                  "previous error")
+               (: "For more information about this error, try `rustc --explain "
+                  (one-or-more alnum) "`.")))
+       (flycheck-error-message err))))
+   errors))
+
+(defun flycheck-rust-manifest-directory ()
+  "Return the nearest directory holding the Cargo manifest.
+
+Return the nearest directory containing the `Cargo.toml' manifest
+file, starting from the current buffer and using
+`locate-dominating-file'.  Return nil if there is no such file,
+or if the current buffer has no file name."
+  (and buffer-file-name
+       (locate-dominating-file buffer-file-name "Cargo.toml")))
+
+(defun flycheck-rust-cargo-metadata ()
+  "Run 'cargo metadata' and return the result as parsed JSON object."
+  (car (flycheck-parse-json
+        (with-output-to-string
+          (call-process "cargo" nil standard-output nil
+                        "metadata" "--no-deps" "--format-version" "1")))))
+
+(defun flycheck-rust-cargo-workspace-root ()
+  "Return the path to the workspace root of a Rust Cargo project.
+
+Return nil if the workspace root does not exist (for Rust
+versions inferior to 1.25)."
+  (let-alist (flycheck-rust-cargo-metadata)
+    .workspace_root))
+
+(defun flycheck-rust-cargo-has-command-p (command)
+  "Whether Cargo has COMMAND in its list of commands.
+
+Execute `cargo --list' to find out whether COMMAND is present."
+  (let ((cargo (funcall flycheck-executable-find "cargo")))
+    (member command (mapcar #'string-trim-left
+                            (ignore-errors (process-lines cargo "--list"))))))
+
+(defun flycheck-rust-valid-crate-type-p (crate-type)
+  "Whether CRATE-TYPE is a valid target type for Cargo.
+
+A valid Cargo target type is one of `lib', `bin', `example',
+`test' or `bench'."
+  (member crate-type '(nil "lib" "bin" "example" "test" "bench")))
+
+(flycheck-define-checker rust-cargo
+  "A Rust syntax checker using Cargo.
+
+This syntax checker requires Rust 1.17 or newer.  See URL
+`https://www.rust-lang.org'."
+  :command ("cargo"
+            (eval (if flycheck-rust-check-tests
+                      "test"
+                    "check"))
+            (eval (when flycheck-rust-check-tests
+                    "--no-run"))
+            (eval (when flycheck-rust-crate-type
+                    (concat "--" flycheck-rust-crate-type)))
+            ;; All crate targets except "lib" need a binary name
+            (eval (when (and flycheck-rust-crate-type
+                             (not (string= flycheck-rust-crate-type "lib")))
+                    flycheck-rust-binary-name))
+            (eval flycheck-cargo-check-args)
+            "--message-format=json")
+  :error-parser flycheck-parse-cargo-rustc
+  :error-filter (lambda (errors)
+                  ;; In Rust 1.25+, filenames are relative to the workspace
+                  ;; root.
+                  (let ((root (flycheck-rust-cargo-workspace-root)))
+                    (seq-do (lambda (err)
+                              (setf (flycheck-error-filename err)
+                                    (expand-file-name
+                                     (flycheck-error-filename err) root)))
+                            (flycheck-rust-error-filter errors))))
+  :error-explainer flycheck-rust-error-explainer
+  :modes rust-mode
+  :predicate flycheck-buffer-saved-p
+  :enabled flycheck-rust-manifest-directory
+  :working-directory (lambda (_) (flycheck-rust-manifest-directory))
+  :verify
+  (lambda (_)
+    (and buffer-file-name
+         (let* ((has-toml (flycheck-rust-manifest-directory))
+                (valid-crate-type (flycheck-rust-valid-crate-type-p
+                                   flycheck-rust-crate-type))
+                (need-binary-name
+                 (and flycheck-rust-crate-type
+                      (not (string= flycheck-rust-crate-type "lib")))))
+           (list
+            (flycheck-verification-result-new
+             :label "Cargo.toml"
+             :message (if has-toml "Found" "Missing")
+             :face (if has-toml 'success '(bold warning)))
+            (flycheck-verification-result-new
+             :label "Crate type"
+             :message (if valid-crate-type
+                          (format "%s" flycheck-rust-crate-type)
+                        (format "%s (invalid, should be one of 'lib', 'bin', \
+'test', 'example' or 'bench')"
+                                flycheck-rust-crate-type))
+             :face (if valid-crate-type 'success '(bold error)))
+            (flycheck-verification-result-new
+             :label "Binary name"
+             :message (cond
+                       ((not need-binary-name) "Not required")
+                       ((not flycheck-rust-binary-name) "Required")
+                       (t (format "%s" flycheck-rust-binary-name)))
+             :face (cond
+                    ((not need-binary-name) 'success)
+                    ((not flycheck-rust-binary-name) '(bold error))
+                    (t 'success))))))))
+
+(flycheck-define-checker rust
+  "A Rust syntax checker using Rust compiler.
+
+This syntax checker needs Rust 1.7 or newer.  See URL
+`https://www.rust-lang.org'."
+  :command ("rustc"
+            (option "--crate-type" flycheck-rust-crate-type)
+            "--error-format=json"
+            (option-flag "--test" flycheck-rust-check-tests)
+            (option-list "-L" flycheck-rust-library-path concat)
+            (eval flycheck-rust-args)
+            (eval (or flycheck-rust-crate-root
+                      (flycheck-substitute-argument 'source-original 'rust))))
+  :error-parser flycheck-parse-rustc
+  :error-filter flycheck-rust-error-filter
+  :error-explainer flycheck-rust-error-explainer
+  :modes rust-mode
+  :predicate flycheck-buffer-saved-p)
+
+(flycheck-define-checker rust-clippy
+  "A Rust syntax checker using clippy.
+
+See URL `https://github.com/rust-lang-nursery/rust-clippy'."
+  :command ("cargo" "+nightly" "clippy" "--message-format=json")
+  :error-parser flycheck-parse-cargo-rustc
+  :error-filter flycheck-rust-error-filter
+  :error-explainer flycheck-rust-error-explainer
+  :modes rust-mode
+  :predicate flycheck-buffer-saved-p
+  :enabled (lambda ()
+             (and (flycheck-rust-cargo-has-command-p "clippy")
+                  (flycheck-rust-manifest-directory)))
+  :working-directory (lambda (_) (flycheck-rust-manifest-directory))
+  :verify
+  (lambda (_)
+    (and buffer-file-name
+         (let ((has-toml (flycheck-rust-manifest-directory))
+               (has-clippy (flycheck-rust-cargo-has-command-p "clippy")))
+           (list
+            (flycheck-verification-result-new
+             :label "Clippy"
+             :message (if has-clippy "Found"
+                        "Cannot find the `cargo clippy' command")
+             :face (if has-clippy 'success '(bold warning)))
+            (flycheck-verification-result-new
+             :label "Cargo.toml"
+             :message (if has-toml "Found" "Missing")
+             :face (if has-toml 'success '(bold warning))))))))
+
+(defvar flycheck-sass-scss-cache-directory nil
+  "The cache directory for `sass' and `scss'.")
+
+(defun flycheck-sass-scss-cache-location ()
+  "Get the cache location for `sass' and `scss'.
+
+If no cache directory exists yet, create one and return it.
+Otherwise return the previously used cache directory."
+  (setq flycheck-sass-scss-cache-directory
+        (or flycheck-sass-scss-cache-directory
+            (make-temp-file "flycheck-sass-scss-cache" 'directory))))
+
+(flycheck-def-option-var flycheck-sass-compass nil sass
+  "Whether to enable the Compass CSS framework.
+
+When non-nil, enable the Compass CSS framework, via `--compass'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-define-checker sass
+  "A Sass syntax checker using the Sass compiler.
+
+See URL `http://sass-lang.com'."
+  :command ("sass"
+            "--cache-location" (eval (flycheck-sass-scss-cache-location))
+            (option-flag "--compass" flycheck-sass-compass)
+            "--check" "--stdin")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (or "Syntax error: " "Error: ")
+          (message (one-or-more not-newline)
+                   (zero-or-more "\n"
+                                 (one-or-more " ")
+                                 (one-or-more not-newline)))
+          (optional "\r") "\n" (one-or-more " ") "on line " line
+          " of standard input"
+          line-end)
+   (warning line-start
+            "WARNING: "
+            (message (one-or-more not-newline)
+                     (zero-or-more "\n"
+                                   (one-or-more " ")
+                                   (one-or-more not-newline)))
+            (optional "\r") "\n" (one-or-more " ") "on line " line
+            " of " (one-or-more not-newline)
+            line-end))
+  :modes sass-mode)
+
+(flycheck-def-config-file-var flycheck-sass-lintrc sass/scss-sass-lint
+                              ".sass-lint.yml"
+  :safe #'stringp
+  :package-version '(flycheck . "30"))
+
+(flycheck-define-checker sass/scss-sass-lint
+  "A SASS/SCSS syntax checker using sass-Lint.
+
+See URL `https://github.com/sasstools/sass-lint'."
+  :command ("sass-lint"
+            "--verbose"
+            "--no-exit"
+            "--format" "Checkstyle"
+            (config-file "--config" flycheck-sass-lintrc)
+            source)
+  :error-parser flycheck-parse-checkstyle
+  :modes (sass-mode scss-mode))
+
+(flycheck-define-checker scala
+  "A Scala syntax checker using the Scala compiler.
+
+See URL `https://www.scala-lang.org/'."
+  :command ("scalac" "-Ystop-after:parser" source)
+  :error-patterns
+  ((error line-start (file-name) ":" line ": error: " (message) line-end))
+  :modes scala-mode
+  :next-checkers ((warning . scala-scalastyle)))
+
+(flycheck-def-config-file-var flycheck-scalastylerc scala-scalastyle nil
+  :safe #'stringp
+  :package-version '(flycheck . "0.20"))
+
+(flycheck-define-checker scala-scalastyle
+  "A Scala style checker using scalastyle.
+
+Note that this syntax checker is not used if
+`flycheck-scalastylerc' is nil or refers to a non-existing file.
+
+See URL `http://www.scalastyle.org'."
+  :command ("scalastyle"
+            (config-file "-c" flycheck-scalastylerc)
+            source)
+  :error-patterns
+  ((error line-start "error file=" (file-name) " message="
+          (message) " line=" line (optional " column=" column) line-end)
+   (warning line-start "warning file=" (file-name) " message="
+            (message) " line=" line (optional " column=" column) line-end))
+  :error-filter (lambda (errors)
+                  (flycheck-sanitize-errors
+                   (flycheck-increment-error-columns errors)))
+  :modes scala-mode
+  :predicate
+  ;; Inhibit this syntax checker if the JAR or the configuration are unset or
+  ;; missing
+  (lambda () (and flycheck-scalastylerc
+                  (flycheck-locate-config-file flycheck-scalastylerc
+                                               'scala-scalastyle)))
+  :verify (lambda (checker)
+            (let ((config-file (and flycheck-scalastylerc
+                                    (flycheck-locate-config-file
+                                     flycheck-scalastylerc checker))))
+              (list
+               (flycheck-verification-result-new
+                :label "Configuration file"
+                :message (cond
+                          ((not flycheck-scalastylerc)
+                           "`flycheck-scalastyletrc' not set")
+                          ((not config-file)
+                           (format "file %s not found" flycheck-scalastylerc))
+                          (t (format "found at %s" config-file)))
+                :face (cond
+                       ((not flycheck-scalastylerc) '(bold warning))
+                       ((not config-file) '(bold error))
+                       (t 'success)))))))
+
+(flycheck-def-args-var flycheck-scheme-chicken-args scheme-chicken
+  :package-version '(flycheck . "32"))
+
+(flycheck-define-checker scheme-chicken
+  "A CHICKEN Scheme syntax checker using the CHICKEN compiler `csc'.
+
+See URL `http://call-cc.org/'."
+  :command ("csc" "-analyze-only" "-local"
+            (eval flycheck-scheme-chicken-args)
+            source)
+  :error-patterns
+  ((info line-start
+         "Note: " (zero-or-more not-newline) ":\n"
+         (one-or-more (any space)) "(" (file-name) ":" line ") " (message)
+         line-end)
+   (warning line-start
+            "Warning: " (zero-or-more not-newline) ":\n"
+            (one-or-more (any space)) "(" (file-name) ":" line ") " (message)
+            line-end)
+   (error line-start "Error: (line " line ") " (message) line-end)
+   (error line-start "Syntax error: (" (file-name) ":" line ")"
+          (zero-or-more not-newline) " - "
+          (message (one-or-more not-newline)
+                   (zero-or-more "\n"
+                                 (zero-or-more space)
+                                 (zero-or-more not-newline))
+                   (one-or-more space) "<--")
+          line-end)
+   (error line-start
+          "Error: " (zero-or-more not-newline) ":\n"
+          (one-or-more (any space)) "(" (file-name) ":" line ") " (message)
+          line-end))
+  :predicate
+  (lambda ()
+    ;; In `scheme-mode' we must check the current Scheme implementation
+    ;; being used
+    (and (boundp 'geiser-impl--implementation)
+         (eq geiser-impl--implementation 'chicken)))
+  :verify
+  (lambda (_checker)
+    (let ((geiser-impl (bound-and-true-p geiser-impl--implementation)))
+      (list
+       (flycheck-verification-result-new
+        :label "Geiser Implementation"
+        :message (cond
+                  ((eq geiser-impl 'chicken) "Chicken Scheme")
+                  (geiser-impl (format "Other: %s" geiser-impl))
+                  (t "Geiser not active"))
+        :face (cond
+               ((eq geiser-impl 'chicken) 'success)
+               (t '(bold error)))))))
+  :modes scheme-mode)
+
+(defconst flycheck-scss-lint-checkstyle-re
+  (rx "cannot load such file" (1+ not-newline) "scss_lint_reporter_checkstyle")
+  "Regular expression to parse missing checkstyle error.")
+
+(defun flycheck-parse-scss-lint (output checker buffer)
+  "Parse SCSS-Lint OUTPUT from CHECKER and BUFFER.
+
+Like `flycheck-parse-checkstyle', but catches errors about
+missing checkstyle reporter from SCSS-Lint."
+  (if (string-match-p flycheck-scss-lint-checkstyle-re output)
+      (list (flycheck-error-new-at
+             1 nil 'error "Checkstyle reporter for SCSS-Lint missing.
+Please run gem install scss_lint_reporter_checkstyle"
+             :checker checker
+             :buffer buffer
+             :filename (buffer-file-name buffer)))
+    (flycheck-parse-checkstyle output checker buffer)))
+
+(flycheck-def-config-file-var flycheck-scss-lintrc scss-lint ".scss-lint.yml"
+  :safe #'stringp
+  :package-version '(flycheck . "0.23"))
+
+(flycheck-define-checker scss-lint
+  "A SCSS syntax checker using SCSS-Lint.
+
+Needs SCSS-Lint 0.43.2 or newer.
+
+See URL `https://github.com/brigade/scss-lint'."
+  :command ("scss-lint"
+            "--require=scss_lint_reporter_checkstyle"
+            "--format=Checkstyle"
+            (config-file "--config" flycheck-scss-lintrc)
+            "--stdin-file-path" source-original "-")
+  :standard-input t
+  ;; We cannot directly parse Checkstyle XML, since for some mysterious reason
+  ;; SCSS-Lint doesn't have a built-in Checkstyle reporter, and instead ships it
+  ;; as an addon which might not be installed.  We use a custom error parser to
+  ;; check whether the addon is missing and turn that into a special kind of
+  ;; Flycheck error.
+  :error-parser flycheck-parse-scss-lint
+  :modes scss-mode
+  :verify
+  (lambda (checker)
+    (let* ((executable (flycheck-find-checker-executable checker))
+           (reporter-missing
+            (and executable
+                 (with-temp-buffer
+                   (call-process executable nil t nil
+                                 "--require=scss_lint_reporter_checkstyle")
+                   (goto-char (point-min))
+                   (re-search-forward
+                    flycheck-scss-lint-checkstyle-re
+                    nil 'no-error)))))
+      (when executable
+        (list
+         (flycheck-verification-result-new
+          :label "checkstyle reporter"
+          :message (if reporter-missing
+                       "scss_lint_reporter_checkstyle missing"
+                     "present")
+          :face (if reporter-missing
+                    '(bold error)
+                  'success)))))))
+
+(flycheck-define-checker scss-stylelint
+  "A SCSS syntax and style checker using stylelint.
+
+See URL `http://stylelint.io/'."
+  :command ("stylelint"
+            (eval flycheck-stylelint-args)
+            "--syntax" "scss"
+            (option-flag "--quiet" flycheck-stylelint-quiet)
+            (config-file "--config" flycheck-stylelintrc))
+  :standard-input t
+  :error-parser flycheck-parse-stylelint
+  :modes (scss-mode))
+
+(flycheck-def-option-var flycheck-scss-compass nil scss
+  "Whether to enable the Compass CSS framework.
+
+When non-nil, enable the Compass CSS framework, via `--compass'."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "0.16"))
+
+(flycheck-define-checker scss
+  "A SCSS syntax checker using the SCSS compiler.
+
+See URL `http://sass-lang.com'."
+  :command ("scss"
+            "--cache-location" (eval (flycheck-sass-scss-cache-location))
+            (option-flag "--compass" flycheck-scss-compass)
+            "--check" "--stdin")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (or "Syntax error: " "Error: ")
+          (message (one-or-more not-newline)
+                   (zero-or-more "\n"
+                                 (one-or-more " ")
+                                 (one-or-more not-newline)))
+          (optional "\r") "\n" (one-or-more " ") "on line " line
+          " of standard input"
+          line-end)
+   (warning line-start
+            "WARNING: "
+            (message (one-or-more not-newline)
+                     (zero-or-more "\n"
+                                   (one-or-more " ")
+                                   (one-or-more not-newline)))
+            (optional "\r") "\n" (one-or-more " ") "on line " line
+            " of an unknown file"
+            line-end))
+  :modes scss-mode)
+
+(flycheck-def-args-var flycheck-sh-bash-args (sh-bash)
+  :package-version '(flycheck . "32"))
+
+(flycheck-define-checker sh-bash
+  "A Bash syntax checker using the Bash shell.
+
+See URL `http://www.gnu.org/software/bash/'."
+  :command ("bash" "--norc" "-n"
+            (eval flycheck-sh-bash-args)
+            "--")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          ;; The name/path of the bash executable
+          (one-or-more (not (any ":"))) ":"
+          ;; A label "line", possibly localized
+          (one-or-more (not (any digit)))
+          line (zero-or-more " ") ":" (zero-or-more " ")
+          (message) line-end))
+  :modes sh-mode
+  :predicate (lambda () (eq sh-shell 'bash))
+  :next-checkers ((warning . sh-shellcheck)))
+
+(flycheck-define-checker sh-posix-dash
+  "A POSIX Shell syntax checker using the Dash shell.
+
+See URL `http://gondor.apana.org.au/~herbert/dash/'."
+  :command ("dash" "-n")
+  :standard-input t
+  :error-patterns
+  ((error line-start (one-or-more (not (any ":"))) ": " line ": " (message)))
+  :modes sh-mode
+  :predicate (lambda () (eq sh-shell 'sh))
+  :next-checkers ((warning . sh-shellcheck)))
+
+(flycheck-define-checker sh-posix-bash
+  "A POSIX Shell syntax checker using the Bash shell.
+
+See URL `http://www.gnu.org/software/bash/'."
+  :command ("bash" "--posix" "--norc" "-n" "--")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          ;; The name/path of the bash executable
+          (one-or-more (not (any ":"))) ":"
+          ;; A label "line", possibly localized
+          (one-or-more (not (any digit)))
+          line (zero-or-more " ") ":" (zero-or-more " ")
+          (message) line-end))
+  :modes sh-mode
+  :predicate (lambda () (eq sh-shell 'sh))
+  :next-checkers ((warning . sh-shellcheck)))
+
+(flycheck-define-checker sh-zsh
+  "A Zsh syntax checker using the Zsh shell.
+
+See URL `http://www.zsh.org/'."
+  :command ("zsh" "--no-exec" "--no-globalrcs" "--no-rcs" source)
+  :error-patterns
+  ((error line-start (file-name) ":" line ": " (message) line-end))
+  :modes sh-mode
+  :predicate (lambda () (eq sh-shell 'zsh))
+  :next-checkers ((warning . sh-shellcheck)))
+
+(defconst flycheck-shellcheck-supported-shells '(bash ksh88 sh)
+  "Shells supported by ShellCheck.")
+
+(flycheck-def-option-var flycheck-shellcheck-excluded-warnings nil sh-shellcheck
+  "A list of excluded warnings for ShellCheck.
+
+The value of this variable is a list of strings, where each
+string is a warning code to be excluded from ShellCheck reports.
+By default, no warnings are excluded."
+  :type '(repeat :tag "Excluded warnings"
+                 (string :tag "Warning code"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.21"))
+
+(flycheck-def-option-var flycheck-shellcheck-follow-sources t sh-shellcheck
+  "Whether to follow external sourced files in scripts.
+
+Shellcheck will follow and parse sourced files so long as a
+pre-runtime resolvable path to the file is present.  This can
+either be part of the source command itself:
+   source /full/path/to/file.txt
+or added as a shellcheck directive before the source command:
+   # shellcheck source=/full/path/to/file.txt."
+  :type 'boolean
+  :safe #'booleanp
+  :package-version '(flycheck . "31"))
+
+(flycheck-define-checker sh-shellcheck
+  "A shell script syntax and style checker using Shellcheck.
+
+See URL `https://github.com/koalaman/shellcheck/'."
+  :command ("shellcheck"
+            "--format" "checkstyle"
+            "--shell" (eval (symbol-name sh-shell))
+            (option-flag "--external-sources"
+                         flycheck-shellcheck-follow-sources)
+            (option "--exclude" flycheck-shellcheck-excluded-warnings list
+                    flycheck-option-comma-separated-list)
+            "-")
+  :standard-input t
+  :error-parser flycheck-parse-checkstyle
+  :error-filter
+  (lambda (errors)
+    (flycheck-remove-error-file-names
+     "-" (flycheck-dequalify-error-ids errors)))
+  :modes sh-mode
+  :predicate (lambda () (memq sh-shell flycheck-shellcheck-supported-shells))
+  :verify (lambda (_)
+            (let ((supports-shell (memq sh-shell
+                                        flycheck-shellcheck-supported-shells)))
+              (list
+               (flycheck-verification-result-new
+                :label (format "Shell %s supported" sh-shell)
+                :message (if supports-shell "yes" "no")
+                :face (if supports-shell 'success '(bold warning)))))))
+
+(flycheck-define-checker slim
+  "A Slim syntax checker using the Slim compiler.
+
+See URL `http://slim-lang.com'."
+  :command ("slimrb" "--compile")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          "Slim::Parser::SyntaxError:" (message) (optional "\r") "\n  "
+          "STDIN, Line " line (optional ", Column " column)
+          line-end))
+  :modes slim-mode
+  :next-checkers ((warning . slim-lint)))
+
+(flycheck-define-checker slim-lint
+  "A Slim linter.
+
+See URL `https://github.com/sds/slim-lint'."
+  :command ("slim-lint" "--reporter=checkstyle" source)
+  :error-parser flycheck-parse-checkstyle
+  :modes slim-mode)
+
+(flycheck-define-checker sql-sqlint
+  "A SQL syntax checker using the sqlint tool.
+
+See URL `https://github.com/purcell/sqlint'."
+  :command ("sqlint")
+  :standard-input t
+  :error-patterns
+  ((warning line-start "stdin:" line ":" column ":WARNING "
+            (message (one-or-more not-newline)
+                     (zero-or-more "\n"
+                                   (one-or-more "  ")
+                                   (one-or-more not-newline)))
+            line-end)
+   (error line-start "stdin:" line ":" column ":ERROR "
+          (message (one-or-more not-newline)
+                   (zero-or-more "\n"
+                                 (one-or-more "  ")
+                                 (one-or-more not-newline)))
+          line-end))
+  :modes (sql-mode))
+
+(flycheck-define-checker systemd-analyze
+  "A systemd unit checker using systemd-analyze(1).
+
+See URL
+`https://www.freedesktop.org/software/systemd/man/systemd-analyze.html'."
+  :command ("systemd-analyze" "verify" source)
+  :error-patterns
+  ((error line-start "[" (file-name) ":" line "] " (message) line-end))
+  :modes (systemd-mode))
+
+(flycheck-def-config-file-var flycheck-chktexrc tex-chktex ".chktexrc"
+  :safe #'stringp)
+
+(flycheck-define-checker tcl-nagelfar
+  "An extensible tcl syntax checker
+
+See URL `http://nagelfar.sourceforge.net/'."
+  :command ("nagelfar" "-H" source)
+  :error-patterns
+  ;; foo.tcl: 29: E Wrong number of arguments (4) to "set"
+  ;; foo.tcl: 29: W Expr without braces
+  ((info    line-start (file-name) ": " line ": N " (message) line-end)
+   (warning line-start (file-name) ": " line ": W " (message) line-end)
+   (error   line-start (file-name) ": " line ": E " (message) line-end))
+  :modes tcl-mode)
+
+(flycheck-define-checker tex-chktex
+  "A TeX and LaTeX syntax and style checker using chktex.
+
+See URL `http://www.nongnu.org/chktex/'."
+  :command ("chktex"
+            (config-file "--localrc" flycheck-chktexrc)
+            ;; Compact error messages, and no version information, and execute
+            ;; \input statements
+            "--verbosity=0" "--quiet" "--inputfiles")
+  :standard-input t
+  :error-patterns
+  ((warning line-start "stdin:" line ":" column ":"
+            (id (one-or-more digit)) ":" (message) line-end))
+  :error-filter
+  (lambda (errors)
+    (flycheck-sanitize-errors (flycheck-increment-error-columns errors)))
+  :modes (latex-mode plain-tex-mode))
+
+(flycheck-define-checker tex-lacheck
+  "A LaTeX syntax and style checker using lacheck.
+
+See URL `http://www.ctan.org/pkg/lacheck'."
+  :command ("lacheck" source-inplace)
+  :error-patterns
+  ((warning line-start
+            "\"" (file-name) "\", line " line ": " (message)
+            line-end))
+  :modes latex-mode)
+
+(flycheck-define-checker texinfo
+  "A Texinfo syntax checker using makeinfo.
+
+See URL `http://www.gnu.org/software/texinfo/'."
+  :command ("makeinfo" "-o" null-device "-")
+  :standard-input t
+  :error-patterns
+  ((warning line-start
+            "-:" line (optional ":" column) ": " "warning: " (message)
+            line-end)
+   (error line-start
+          "-:" line (optional ":" column) ": " (message)
+          line-end))
+  :modes texinfo-mode)
+
+(flycheck-def-config-file-var flycheck-typescript-tslint-config
+    typescript-tslint "tslint.json"
+  :safe #'stringp
+  :package-version '(flycheck . "27"))
+
+(flycheck-def-option-var flycheck-typescript-tslint-rulesdir
+    nil typescript-tslint
+  "The directory of custom rules for TSLint.
+
+The value of this variable is either a string containing the path
+to a directory with custom rules, or nil, to not give any custom
+rules to TSLint.
+
+Refer to the TSLint manual at URL
+`http://palantir.github.io/tslint/usage/cli/'
+for more information about the custom directory."
+  :type '(choice (const :tag "No custom rules directory" nil)
+                 (directory :tag "Custom rules directory"))
+  :safe #'stringp
+  :package-version '(flycheck . "27"))
+
+(flycheck-def-args-var flycheck-tslint-args (typescript-tslint)
+  :package-version '(flycheck . "31"))
+
+(flycheck-define-checker typescript-tslint
+  "TypeScript style checker using TSLint.
+
+Note that this syntax checker is not used if
+`flycheck-typescript-tslint-config' is nil or refers to a
+non-existing file.
+
+See URL `https://github.com/palantir/tslint'."
+  :command ("tslint" "--format" "json"
+            (config-file "--config" flycheck-typescript-tslint-config)
+            (option "--rules-dir" flycheck-typescript-tslint-rulesdir)
+            (eval flycheck-tslint-args)
+            source-inplace)
+  :error-parser flycheck-parse-tslint
+  :modes (typescript-mode))
+
+(flycheck-def-option-var flycheck-verilator-include-path nil verilog-verilator
+  "A list of include directories for Verilator.
+
+The value of this variable is a list of strings, where each
+string is a directory to add to the include path of Verilator.
+Relative paths are relative to the file being checked."
+  :type '(repeat (directory :tag "Include directory"))
+  :safe #'flycheck-string-list-p
+  :package-version '(flycheck . "0.24"))
+
+(flycheck-define-checker verilog-verilator
+  "A Verilog syntax checker using the Verilator Verilog HDL simulator.
+
+See URL `https://www.veripool.org/wiki/verilator'."
+  :command ("verilator" "--lint-only" "-Wall"
+            (option-list "-I" flycheck-verilator-include-path concat)
+            source)
+  :error-patterns
+  ((warning line-start "%Warning-" (zero-or-more not-newline) ": "
+            (file-name) ":" line ": " (message) line-end)
+   (error line-start "%Error: " (file-name) ":"
+          line ": " (message) line-end))
+  :modes verilog-mode)
+
+(flycheck-def-option-var flycheck-ghdl-language-standard nil vhdl-ghdl
+  "The language standard to use in GHDL.
+
+The value of this variable is either a string denoting a language
+standard, or nil, to use the default standard.  When non-nil,
+pass the language standard via the `--std' option."
+  :type '(choice (const :tag "Default standard" nil)
+                 (string :tag "Language standard"))
+  :safe #'stringp
+  :package-version '(flycheck . "32"))
+(make-variable-buffer-local 'flycheck-ghdl-language-standard)
+
+(flycheck-def-option-var flycheck-ghdl-workdir nil vhdl-ghdl
+  "The directory to use for the file library
+
+The value of this variable is either a string with the directory
+to use for the file library, or nil, to use the default value.
+When non-nil, pass the directory via the `--workdir' option."
+  :type '(choice (const :tag "Default directory" nil)
+                 (string :tag "Directory for the file library"))
+  :safe #'stringp
+  :package-version '(flycheck . "32"))
+(make-variable-buffer-local 'flycheck-ghdl-workdir)
+
+(flycheck-define-checker vhdl-ghdl
+  "A VHDL syntax checker using GHDL.
+
+See URL `https://github.com/ghdl/ghdl'."
+  :command ("ghdl"
+            "-s" ; only do the syntax checking
+            (option "--std=" flycheck-ghdl-language-standard concat)
+            (option "--workdir=" flycheck-ghdl-workdir concat)
+            source)
+  :error-patterns
+  ((error line-start (file-name) ":" line ":" column ": " (message) line-end))
+  :modes vhdl-mode)
+
+(flycheck-def-option-var flycheck-xml-xmlstarlet-xsd-path nil xml-xmlstarlet
+  "An XSD schema to validate against."
+  :type '(file :tag "XSD schema")
+  :safe #'stringp
+  :package-version '(flycheck . "31"))
+
+(flycheck-define-checker xml-xmlstarlet
+  "A XML syntax checker and validator using the xmlstarlet utility.
+
+See URL `http://xmlstar.sourceforge.net/'."
+  ;; Validate standard input with verbose error messages, and do not dump
+  ;; contents to standard output
+  :command ("xmlstarlet" "val" "--err" "--quiet"
+            (option "--xsd" flycheck-xml-xmlstarlet-xsd-path)
+            "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start "-:" line "." column ": " (message) line-end))
+  :modes (xml-mode nxml-mode))
+
+(flycheck-def-option-var flycheck-xml-xmllint-xsd-path nil xml-xmllint
+  "An XSD schema to validate against."
+  :type '(file :tag "XSD schema")
+  :safe #'stringp
+  :package-version '(flycheck . "31"))
+
+(flycheck-define-checker xml-xmllint
+  "A XML syntax checker and validator using the xmllint utility.
+
+The xmllint is part of libxml2, see URL
+`http://www.xmlsoft.org/'."
+  :command ("xmllint" "--noout"
+            (option "--schema" flycheck-xml-xmllint-xsd-path)
+            "-")
+  :standard-input t
+  :error-patterns
+  ((error line-start "-:" line ": " (message) line-end))
+  :modes (xml-mode nxml-mode))
+
+(flycheck-define-checker yaml-jsyaml
+  "A YAML syntax checker using JS-YAML.
+
+See URL `https://github.com/nodeca/js-yaml'."
+  :command ("js-yaml")
+  :standard-input t
+  :error-patterns
+  ((error line-start
+          (or "JS-YAML" "YAMLException") ": "
+          (message) " at line " line ", column " column ":"
+          line-end))
+  :modes yaml-mode
+  :next-checkers ((warning . cwl)))
+
+(flycheck-define-checker yaml-ruby
+  "A YAML syntax checker using Ruby's YAML parser.
+
+This syntax checker uses the YAML parser from Ruby's standard
+library.
+
+See URL `http://www.ruby-doc.org/stdlib-2.0.0/libdoc/yaml/rdoc/YAML.html'."
+  :command ("ruby" "-ryaml" "-e" "begin;
+   YAML.load(STDIN); \
+ rescue Exception => e; \
+   STDERR.puts \"stdin:#{e}\"; \
+ end")
+  :standard-input t
+  :error-patterns
+  ((error line-start "stdin:" (zero-or-more not-newline) ":" (message)
+          "at line " line " column " column line-end))
+  :modes yaml-mode
+  :next-checkers ((warning . cwl)))
+
+(provide 'flycheck)
+
+;; Local Variables:
+;; coding: utf-8
+;; indent-tabs-mode: nil
+;; End:
+
+;;; flycheck.el ends here