2 files changed, 228 insertions, 0 deletions
diff --git a/users/Profpatsch/nixpkgs-rewriter/MetaStdenvLib.hs b/users/Profpatsch/nixpkgs-rewriter/MetaStdenvLib.hs
new file mode 100644
index 000000000000..3ed96a7b6eac
--- /dev/null
+++ b/users/Profpatsch/nixpkgs-rewriter/MetaStdenvLib.hs
@@ -0,0 +1,80 @@
+{-# LANGUAGE PartialTypeSignatures #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE NamedFieldPuns #-}
+import Nix.Parser
+import Nix.Expr.Types
+import Nix.Expr.Types.Annotated
+import System.Environment (getArgs)
+import System.Exit (die)
+import Data.Fix (Fix(..))
+import qualified Data.Text as Text
+import qualified Data.ByteString.Lazy.Char8 as BL
+import qualified Data.Aeson as A
+import qualified Data.Aeson.Encoding as A
+import Data.Function ((&))
+import qualified System.IO as IO
+import qualified Text.Megaparsec.Pos as MP
+
+main = do
+  (nixFile:_) <- getArgs
+  (parseNixFileLoc nixFile :: IO _) >>= \case
+    Failure err -> do
+      ePutStrLn $ show err
+      die "oh no"
+    Success expr -> do
+      case snd $ match expr of
+        NoArguments -> do
+          ePutStrLn $ "NoArguments in " <> nixFile
+          printPairs mempty
+        YesLib vars -> do
+          ePutStrLn $ "lib in " <> show vars <> " in " <> nixFile
+          printPairs mempty
+        NoLib vars srcSpan -> do
+          ePutStrLn $ nixFile <> " needs lib added"
+          printPairs
+            $ "fileName" A..= nixFile
+            <> "fromLine" A..= (srcSpan & spanBegin & sourceLine)
+            <> "fromColumn" A..= (srcSpan & spanBegin & sourceColumn)
+            <> "toLine" A..= (srcSpan & spanEnd & sourceLine)
+            <> "toColumn" A..= (srcSpan & spanEnd & sourceColumn)
+
+printPairs pairs = BL.putStrLn $ A.encodingToLazyByteString $ A.pairs pairs
+
+ePutStrLn = IO.hPutStrLn IO.stderr
+
+data Descend = YesDesc | NoDesc
+  deriving Show
+data Matched =  NoArguments | NoLib [VarName] SrcSpan | YesLib [VarName]
+  deriving Show
+
+match :: Fix (Compose (Ann SrcSpan) NExprF) -> (Descend, Matched)
+match = \case
+  (AnnE outerSpan (NAbs (ParamSet params _ _) (AnnE innerSpan _))) -> (NoDesc,
+    let vars = map fst params in
+    case (any (== "lib") vars) of
+      True -> YesLib vars
+      False ->
+          -- The span of the arglist is from the beginning of the match
+          -- to the beginning of the inner expression
+          let varSpan = SrcSpan
+                { spanBegin = outerSpan & spanBegin
+                -- -1 to prevent the spans from overlapping
+                , spanEnd = sourcePosMinus1 (innerSpan & spanBegin) }
+          in NoLib vars varSpan)
+  _ -> (NoDesc, NoArguments)
+
+-- | Remove one from a source positon.
+--
+-- That means if the current position is at the very beginning of a line,
+-- jump to the previous line.
+sourcePosMinus1 :: SourcePos -> SourcePos
+sourcePosMinus1 src@(SourcePos { sourceLine, sourceColumn }) =
+  let
+    col = MP.mkPos $ max (MP.unPos sourceColumn - 1) 1
+    line = MP.mkPos $ case MP.unPos sourceColumn of
+      1 -> max (MP.unPos sourceLine - 1) 1
+      _ -> MP.unPos sourceLine
+  in src
+    { sourceLine = line
+    , sourceColumn = col }
diff --git a/users/Profpatsch/nixpkgs-rewriter/default.nix b/users/Profpatsch/nixpkgs-rewriter/default.nix
new file mode 100644
index 000000000000..0740a870aa4a
--- /dev/null
+++ b/users/Profpatsch/nixpkgs-rewriter/default.nix
@@ -0,0 +1,148 @@
+{ depot, pkgs, ... }:
+let
+  inherit (depot.nix)
+    writeExecline
+    ;
+  inherit (depot.users.Profpatsch.lib)
+    debugExec
+    ;
+
+  bins = depot.nix.getBins pkgs.coreutils [ "head" "shuf" ]
+    // depot.nix.getBins pkgs.jq [ "jq" ]
+    // depot.nix.getBins pkgs.findutils [ "xargs" ]
+    // depot.nix.getBins pkgs.gnused [ "sed" ]
+  ;
+
+  export-json-object = pkgs.writers.writePython3 "export-json-object" { } ''
+    import json
+    import sys
+    import os
+
+    d = json.load(sys.stdin)
+
+    if d == {}:
+        sys.exit(0)
+
+    for k, v in d.items():
+        os.environ[k] = str(v)
+
+    os.execvp(sys.argv[1], sys.argv[1:])
+  '';
+
+  meta-stdenv-lib = pkgs.writers.writeHaskell "meta-stdenv-lib"
+    {
+      libraries = [
+        pkgs.haskellPackages.hnix
+        pkgs.haskellPackages.aeson
+      ];
+    } ./MetaStdenvLib.hs;
+
+  replace-between-lines = writeExecline "replace-between-lines" { readNArgs = 1; } [
+    "importas"
+    "-ui"
+    "file"
+    "fileName"
+    "importas"
+    "-ui"
+    "from"
+    "fromLine"
+    "importas"
+    "-ui"
+    "to"
+    "toLine"
+    "if"
+    [ depot.tools.eprintf "%s-%s\n" "$from" "$to" ]
+    (debugExec "adding lib")
+    bins.sed
+    "-e"
+    "\${from},\${to} \${1}"
+    "-i"
+    "$file"
+  ];
+
+  add-lib-if-necessary = writeExecline "add-lib-if-necessary" { readNArgs = 1; } [
+    "pipeline"
+    [ meta-stdenv-lib "$1" ]
+    export-json-object
+    # first replace any stdenv.lib mentions in the arg header
+    # if this is not done, the replace below kills these.
+    # Since we want it anyway ultimately, let’s do it here.
+    "if"
+    [ replace-between-lines "s/stdenv\.lib/lib/" ]
+    # then add the lib argument
+    # (has to be before stdenv, otherwise default arguments might be in the way)
+    replace-between-lines
+    "s/stdenv/lib, stdenv/"
+  ];
+
+  metaString = ''meta = with stdenv.lib; {'';
+
+  replace-stdenv-lib = pkgs.writers.writeBash "replace-stdenv-lib" ''
+    set -euo pipefail
+    sourceDir="$1"
+    for file in $(
+      ${pkgs.ripgrep}/bin/rg \
+        --files-with-matches \
+        --fixed-strings \
+        -e '${metaString}' \
+        "$sourceDir"
+    )
+    do
+      echo "replacing stdenv.lib meta in $file" >&2
+      ${bins.sed} -e '/${metaString}/ s/stdenv.lib/lib/' \
+          -i "$file"
+      ${add-lib-if-necessary} "$file"
+    done
+  '';
+
+  instantiate-nixpkgs-randomly = writeExecline "instantiate-nixpkgs-randomly" { readNArgs = 1; } [
+    "export"
+    "NIXPKGS_ALLOW_BROKEN"
+    "1"
+    "export"
+    "NIXPKGS_ALLOW_UNFREE"
+    "1"
+    "export"
+    "NIXPKGS_ALLOW_INSECURE"
+    "1"
+    "export"
+    "NIXPKGS_ALLOW_UNSUPPORTED_SYSTEM"
+    "1"
+    "pipeline"
+    [
+      "nix"
+      "eval"
+      "--raw"
+      ''(
+          let pkgs = import ''${1} {};
+          in builtins.toJSON (builtins.attrNames pkgs)
+        )''
+    ]
+    "pipeline"
+    [ bins.jq "-r" ".[]" ]
+    "pipeline"
+    [ bins.shuf ]
+    "pipeline"
+    [ bins.head "-n" "1000" ]
+    bins.xargs
+    "-I"
+    "{}"
+    "-n1"
+    "if"
+    [ depot.tools.eprintf "instantiating %s\n" "{}" ]
+    "nix-instantiate"
+    "$1"
+    "-A"
+    "{}"
+  ];
+
+in
+depot.nix.readTree.drvTargets {
+  inherit
+    instantiate-nixpkgs-randomly
+    # requires hnix, which we don’t want in tvl for now
+    # uncomment manually if you want to use it.
+    #   meta-stdenv-lib
+    #   replace-stdenv-lib
+    ;
+}