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-rw-r--r--absl/base/BUILD.bazel3
-rw-r--r--absl/base/CMakeLists.txt1
-rw-r--r--absl/base/config.h63
-rw-r--r--absl/base/internal/endian.h8
-rw-r--r--absl/base/options.h188
5 files changed, 254 insertions, 9 deletions
diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index ffeca630706e..6fc712d968f3 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -87,6 +87,7 @@ cc_library(
     name = "config",
     hdrs = [
         "config.h",
+        "options.h",
         "policy_checks.h",
     ],
     copts = ABSL_DEFAULT_COPTS,
@@ -137,7 +138,7 @@ cc_library(
         "//conditions:default": ["-pthread"],
     }) + ABSL_DEFAULT_LINKOPTS,
     visibility = [
-        "//absl:__subpackages__",
+        "//visibility:public",
     ],
     deps = [
         ":base",
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 2698213c566d..9550cdb2db49 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -75,6 +75,7 @@ absl_cc_library(
     config
   HDRS
     "config.h"
+    "options.h"
     "policy_checks.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
diff --git a/absl/base/config.h b/absl/base/config.h
index 24851fa33ce4..46a84f1a76f6 100644
--- a/absl/base/config.h
+++ b/absl/base/config.h
@@ -63,6 +63,7 @@
 #include <TargetConditionals.h>
 #endif
 
+#include "absl/base/options.h"
 #include "absl/base/policy_checks.h"
 
 // -----------------------------------------------------------------------------
@@ -468,6 +469,68 @@
 #define ABSL_HAVE_STD_STRING_VIEW 1
 #endif
 
+// ABSL_USES_STD_ANY
+//
+// Indicates whether absl::any is an alias for std::any.
+#if !defined(ABSL_OPTION_USE_STD_ANY)
+#error options.h is misconfigured.
+#elif ABSL_OPTION_USE_STD_ANY == 0 || \
+    (ABSL_OPTION_USE_STD_ANY == 2 && !defined(ABSL_HAVE_STD_ANY))
+#undef ABSL_USES_STD_ANY
+#elif ABSL_OPTION_USE_STD_ANY == 1 || \
+    (ABSL_OPTION_USE_STD_ANY == 2 && defined(ABSL_HAVE_STD_ANY))
+#define ABSL_USES_STD_ANY 1
+#else
+#error options.h is misconfigured.
+#endif
+
+// ABSL_USES_STD_OPTIONAL
+//
+// Indicates whether absl::optional is an alias for std::optional.
+#if !defined(ABSL_OPTION_USE_STD_OPTIONAL)
+#error options.h is misconfigured.
+#elif ABSL_OPTION_USE_STD_OPTIONAL == 0 || \
+    (ABSL_OPTION_USE_STD_OPTIONAL == 2 && !defined(ABSL_HAVE_STD_OPTIONAL))
+#undef ABSL_USES_STD_OPTIONAL
+#elif ABSL_OPTION_USE_STD_OPTIONAL == 1 || \
+    (ABSL_OPTION_USE_STD_OPTIONAL == 2 && defined(ABSL_HAVE_STD_OPTIONAL))
+#define ABSL_USES_STD_OPTIONAL 1
+#else
+#error options.h is misconfigured.
+#endif
+
+// ABSL_USES_STD_VARIANT
+//
+// Indicates whether absl::variant is an alias for std::variant.
+#if !defined(ABSL_OPTION_USE_STD_VARIANT)
+#error options.h is misconfigured.
+#elif ABSL_OPTION_USE_STD_VARIANT == 0 || \
+    (ABSL_OPTION_USE_STD_VARIANT == 2 && !defined(ABSL_HAVE_STD_VARIANT))
+#undef ABSL_USES_STD_VARIANT
+#elif ABSL_OPTION_USE_STD_VARIANT == 1 || \
+    (ABSL_OPTION_USE_STD_VARIANT == 2 && defined(ABSL_HAVE_STD_VARIANT))
+#define ABSL_USES_STD_VARIANT 1
+#else
+#error options.h is misconfigured.
+#endif
+
+// ABSL_USES_STD_STRING_VIEW
+//
+// Indicates whether absl::string_view is an alias for std::string_view.
+#if !defined(ABSL_OPTION_USE_STD_STRING_VIEW)
+#error options.h is misconfigured.
+#elif ABSL_OPTION_USE_STD_STRING_VIEW == 0 || \
+    (ABSL_OPTION_USE_STD_STRING_VIEW == 2 &&  \
+     !defined(ABSL_HAVE_STD_STRING_VIEW))
+#undef ABSL_USES_STD_STRING_VIEW
+#elif ABSL_OPTION_USE_STD_STRING_VIEW == 1 || \
+    (ABSL_OPTION_USE_STD_STRING_VIEW == 2 &&  \
+     defined(ABSL_HAVE_STD_STRING_VIEW))
+#define ABSL_USES_STD_STRING_VIEW 1
+#else
+#error options.h is misconfigured.
+#endif
+
 // In debug mode, MSVC 2017's std::variant throws a EXCEPTION_ACCESS_VIOLATION
 // SEH exception from emplace for variant<SomeStruct> when constructing the
 // struct can throw. This defeats some of variant_test and
diff --git a/absl/base/internal/endian.h b/absl/base/internal/endian.h
index b43c9a46ee35..8233cb52433b 100644
--- a/absl/base/internal/endian.h
+++ b/absl/base/internal/endian.h
@@ -19,9 +19,6 @@
 // The following guarantees declaration of the byte swap functions
 #ifdef _MSC_VER
 #include <stdlib.h>  // NOLINT(build/include)
-#elif defined(__APPLE__)
-// macOS / Darwin features
-#include <libkern/OSByteOrder.h>
 #elif defined(__FreeBSD__)
 #include <sys/endian.h>
 #elif defined(__GLIBC__)
@@ -63,11 +60,6 @@ inline uint16_t gbswap_16(uint16_t host_int) {
   return _byteswap_ushort(host_int);
 }
 
-#elif defined(__APPLE__)
-inline uint64_t gbswap_64(uint64_t host_int) { return OSSwapInt16(host_int); }
-inline uint32_t gbswap_32(uint32_t host_int) { return OSSwapInt32(host_int); }
-inline uint16_t gbswap_16(uint16_t host_int) { return OSSwapInt64(host_int); }
-
 #else
 inline uint64_t gbswap_64(uint64_t host_int) {
 #if defined(__GNUC__) && defined(__x86_64__) && !defined(__APPLE__)
diff --git a/absl/base/options.h b/absl/base/options.h
new file mode 100644
index 000000000000..3961e63f4e2a
--- /dev/null
+++ b/absl/base/options.h
@@ -0,0 +1,188 @@
+#ifndef ABSL_BASE_OPTIONS_H_
+#define ABSL_BASE_OPTIONS_H_
+
+// Copyright 2019 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// -----------------------------------------------------------------------------
+// File: options.h
+// -----------------------------------------------------------------------------
+//
+// This file contains Abseil configuration options for setting specific
+// implementations instead of letting Abseil determine which implementation to
+// use at compile-time. Setting these options may be useful for package or build
+// managers who wish to guarantee ABI stability within binary builds (which are
+// otherwise difficult to enforce).
+//
+// *** IMPORTANT NOTICE FOR PACKAGE MANAGERS:  It is important that
+// maintainers of package managers who wish to package Abseil read and
+// understand this file! ***
+//
+// Abseil contains a number of possible configuration endpoints, based on
+// parameters such as the detected platform, language version, or command-line
+// flags used to invoke the underlying binary. As is the case with all
+// libraries, binaries which contain Abseil code must ensure that separate
+// packages use the same compiled copy of Abseil to avoid a diamond dependency
+// problem, which can occur if two packages built with different Abseil
+// configuration settings are linked together. Diamond dependency problems in
+// C++ may manifest as violations to the One Definition Rule (ODR) (resulting in
+// linker errors), or undefined behavior (resulting in crashes).
+//
+// Diamond dependency problems can be avoided if all packages utilize the same
+// exact version of Abseil. Building from source code with the same compilation
+// parameters is the easiest way to avoid such dependency problems. However, for
+// package managers who cannot control such compilation parameters, we are
+// providing the file to allow you to inject ABI (Application Binary Interface)
+// stability across builds. Settings options in this file will neither change
+// API nor ABI, providing a stable copy of Abseil between packages.
+//
+// Care must be taken to keep options within these configurations isolated
+// from any other dynamic settings, such as command-line flags which could alter
+// these options. This file is provided specifically to help build and package
+// managers provide a stable copy of Abseil within their libraries and binaries;
+// other developers should not have need to alter the contents of this file.
+//
+// -----------------------------------------------------------------------------
+// Usage
+// -----------------------------------------------------------------------------
+//
+// For any particular package release, set the appropriate definitions within
+// this file to whatever value makes the most sense for your package(s). Note
+// that, by default, most of these options, at the moment, affect the
+// implementation of types; future options may affect other implementation
+// details.
+//
+// NOTE: the defaults within this file all assume that Abseil can select the
+// proper Abseil implementation at compile-time, which will not be sufficient
+// to guarantee ABI stability to package managers.
+//
+// -----------------------------------------------------------------------------
+// Type Compatibility Options
+// -----------------------------------------------------------------------------
+//
+// ABSL_OPTION_USE_STD_ANY
+//
+// This option controls whether absl::any is implemented as an alias to
+// std::any, or as an independent implementation.
+//
+// A value of 0 means to use Abseil's implementation.  This requires only C++11
+// support, and is expected to work on every toolchain we support.
+//
+// A value of 1 means to use an alias to std::any.  This requires that all code
+// using Abseil is built in C++17 mode or later.
+//
+// A value of 2 means to detect the C++ version being used to compile Abseil,
+// and use an alias only if a working std::any is available.  This option is
+// useful when you are building your entire program, including all of its
+// dependencies, from source.  It should not be used otherwise -- for example,
+// if you are distributing Abseil in a binary package manager -- since in
+// mode 2, absl::any will name a different type, with a different mangled name
+// and binary layout, depending on the compiler flags passed by the end user.
+// For more info, see https://abseil.io/about/design/dropin-types.
+//
+// User code should not inspect this macro.  To check in the preprocessor if
+// absl::any is a typedef of std::any, use the feature macro ABSL_USES_STD_ANY.
+
+#define ABSL_OPTION_USE_STD_ANY 2
+
+
+// ABSL_OPTION_USE_STD_OPTIONAL
+//
+// This option controls whether absl::optional is implemented as an alias to
+// std::optional, or as an independent implementation.
+//
+// A value of 0 means to use Abseil's implementation.  This requires only C++11
+// support, and is expected to work on every toolchain we support.
+//
+// A value of 1 means to use an alias to std::optional.  This requires that all
+// code using Abseil is built in C++17 mode or later.
+//
+// A value of 2 means to detect the C++ version being used to compile Abseil,
+// and use an alias only if a working std::optional is available.  This option
+// is useful when you are building your program from source.  It should not be
+// used otherwise -- for example, if you are distributing Abseil in a binary
+// package manager -- since in mode 2, absl::optional will name a different
+// type, with a different mangled name and binary layout, depending on the
+// compiler flags passed by the end user.  For more info, see
+// https://abseil.io/about/design/dropin-types.
+
+// A value of 2 means to detect the C++ version being used to compile Abseil,
+// and use an alias only if a working std::optional is available.  This option
+// should not be used when your program is not built from source -- for example,
+// if you are distributing Abseil in a binary package manager -- since in mode
+// 2, absl::optional will name a different template class, with a different
+// mangled name and binary layout, depending on the compiler flags passed by the
+// end user.
+//
+// User code should not inspect this macro.  To check in the preprocessor if
+// absl::optional is a typedef of std::optional, use the feature macro
+// ABSL_USES_STD_OPTIONAL.
+
+#define ABSL_OPTION_USE_STD_OPTIONAL 2
+
+
+// ABSL_OPTION_USE_STD_STRING_VIEW
+//
+// This option controls whether absl::string_view is implemented as an alias to
+// std::string_view, or as an independent implementation.
+//
+// A value of 0 means to use Abseil's implementation.  This requires only C++11
+// support, and is expected to work on every toolchain we support.
+//
+// A value of 1 means to use an alias to std::string_view.  This requires that
+// all code using Abseil is built in C++17 mode or later.
+//
+// A value of 2 means to detect the C++ version being used to compile Abseil,
+// and use an alias only if a working std::string_view is available.  This
+// option is useful when you are building your program from source.  It should
+// not be used otherwise -- for example, if you are distributing Abseil in a
+// binary package manager -- since in mode 2, absl::string_view will name a
+// different type, with a different mangled name and binary layout, depending on
+// the compiler flags passed by the end user.  For more info, see
+// https://abseil.io/about/design/dropin-types.
+//
+// User code should not inspect this macro.  To check in the preprocessor if
+// absl::string_view is a typedef of std::string_view, use the feature macro
+// ABSL_USES_STD_STRING_VIEW.
+
+#define ABSL_OPTION_USE_STD_STRING_VIEW 2
+
+
+// ABSL_OPTION_USE_STD_VARIANT
+//
+// This option controls whether absl::variant is implemented as an alias to
+// std::variant, or as an independent implementation.
+//
+// A value of 0 means to use Abseil's implementation.  This requires only C++11
+// support, and is expected to work on every toolchain we support.
+//
+// A value of 1 means to use an alias to std::variant.  This requires that all
+// code using Abseil is built in C++17 mode or later.
+//
+// A value of 2 means to detect the C++ version being used to compile Abseil,
+// and use an alias only if a working std::variant is available.  This option
+// is useful when you are building your program from source.  It should not be
+// used otherwise -- for example, if you are distributing Abseil in a binary
+// package manager -- since in mode 2, absl::variant will name a different
+// type, with a different mangled name and binary layout, depending on the
+// compiler flags passed by the end user.  For more info, see
+// https://abseil.io/about/design/dropin-types.
+//
+// User code should not inspect this macro.  To check in the preprocessor if
+// absl::variant is a typedef of std::variant, use the feature macro
+// ABSL_USES_STD_VARIANT.
+
+#define ABSL_OPTION_USE_STD_VARIANT 2
+
+#endif  // ABSL_BASE_OPTIONS_H_