CMakeLists.txt - third_party/github/abseil/abseil-cpp - Git at Google


            
            #

            
            # Copyright 2017 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.

            
            #


            # https://github.com/google/oss-policies-info/blob/main/foundational-cxx-support-matrix.md

            
            # As of 2024-07-01, CMake 3.16 is the minimum supported version.

            
            cmake_minimum_required(VERSION 3.16)


            # Allow the user to specify the CMAKE_MSVC_DEBUG_INFORMATION_FORMAT

            
            if (POLICY CMP0141)

            
              cmake_policy(SET CMP0141 NEW)

            
            endif (POLICY CMP0141)


            project(absl LANGUAGES CXX)

            
            set(ABSL_SOVERSION 0)

            
            include(CTest)


            # Output directory is correct by default for most build setups. However, when

            
            # building Abseil as a DLL, it is important to have the DLL in the same

            
            # directory as the executable using it. Thus, we put all executables in a single

            
            # /bin directory.

            
            set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)


            # when absl is included as subproject (i.e. using add_subdirectory(abseil-cpp))

            
            # in the source tree of a project that uses it, install rules are disabled.

            
            if(NOT CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)

            
              option(ABSL_ENABLE_INSTALL "Enable install rule" OFF)

            
            else()

            
              option(ABSL_ENABLE_INSTALL "Enable install rule" ON)

            
            endif()


            set(CMAKE_INSTALL_RPATH "$ORIGIN")

            
            set(CMAKE_INSTALL_RPATH_USE_LINK_PATH ON)

            
            set(CMAKE_BUILD_RPATH_USE_ORIGIN ON)


            option(ABSL_PROPAGATE_CXX_STD

            
              "Use CMake C++ standard meta features (e.g. cxx_std_17) that propagate to targets that link to Abseil"

            
              ON)


            option(ABSL_USE_SYSTEM_INCLUDES

            
              "Silence warnings in Abseil headers by marking them as SYSTEM includes"

            
              OFF)


            list(APPEND CMAKE_MODULE_PATH

            
              ${CMAKE_CURRENT_LIST_DIR}/CMake

            
              ${CMAKE_CURRENT_LIST_DIR}/absl/copts

            
            )


            option(ABSL_MSVC_STATIC_RUNTIME

            
              "Link static runtime libraries"

            
              OFF)

            
            if(ABSL_MSVC_STATIC_RUNTIME)

            
              set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")

            
            else()

            
              set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>DLL")

            
            endif()


            include(CMakePackageConfigHelpers)

            
            include(GNUInstallDirs)

            
            include(AbseilDll)

            
            include(AbseilHelpers)


            ##

            
            ## Using absl targets

            
            ##

            
            ## all public absl targets are

            
            ## exported with the absl:: prefix

            
            ##

            
            ## e.g absl::base absl::synchronization absl::strings ....

            
            ##

            
            ## DO NOT rely on the internal targets outside of the prefix


            # include current path

            
            list(APPEND ABSL_COMMON_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR})


            if("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")

            
              set(ABSL_USING_CLANG ON)

            
            else()

            
              set(ABSL_USING_CLANG OFF)

            
            endif()


            # find dependencies

            
            ## pthread

            
            find_package(Threads REQUIRED)


            include(CMakeDependentOption)


            option(ABSL_BUILD_TESTING

            
              "If ON, Abseil will build all of Abseil's own tests." OFF)


            option(ABSL_BUILD_TEST_HELPERS

            
              "If ON, Abseil will build libraries that you can use to write tests against Abseil code. This option requires that Abseil is configured to use GoogleTest."

            
              OFF)


            option(ABSL_USE_EXTERNAL_GOOGLETEST

            
              "If ON, Abseil will assume that the targets for GoogleTest are already provided by the including project. This makes sense when Abseil is used with add_subdirectory." OFF)


            cmake_dependent_option(ABSL_FIND_GOOGLETEST

            
              "If ON, Abseil will use find_package(GTest) rather than assuming that GoogleTest is already provided by the including project."

            
              ON

            
              "ABSL_USE_EXTERNAL_GOOGLETEST"

            
              OFF)


            option(ABSL_USE_GOOGLETEST_HEAD

            
              "If ON, abseil will download HEAD from GoogleTest at config time." OFF)


            set(ABSL_GOOGLETEST_DOWNLOAD_URL "" CACHE STRING "If set, download GoogleTest from this URL")


            set(ABSL_LOCAL_GOOGLETEST_DIR "/usr/src/googletest" CACHE PATH

            
              "If ABSL_USE_GOOGLETEST_HEAD is OFF and ABSL_GOOGLETEST_URL is not set, specifies the directory of a local GoogleTest checkout."

            
              )


            option(ABSL_BUILD_MONOLITHIC_SHARED_LIBS

            
              "Build Abseil as a single shared library (always enabled for Windows)"

            
              OFF

            
            )

            
            if(NOT BUILD_SHARED_LIBS AND ABSL_BUILD_MONOLITHIC_SHARED_LIBS)

            
              message(WARNING "Not building a shared library because BUILD_SHARED_LIBS is not set. Ignoring ABSL_BUILD_MONOLITHIC_SHARED_LIBS.")

            
            endif()


            if((BUILD_TESTING AND ABSL_BUILD_TESTING) OR ABSL_BUILD_TEST_HELPERS)

            
              if (ABSL_USE_EXTERNAL_GOOGLETEST)

            
                if (ABSL_FIND_GOOGLETEST)

            
                  find_package(GTest REQUIRED)

            
                elseif(NOT TARGET GTest::gtest)

            
                  if(TARGET gtest)

            
                    # When Google Test is included directly rather than through find_package, the aliases are missing.

            
                    add_library(GTest::gtest ALIAS gtest)

            
                    add_library(GTest::gtest_main ALIAS gtest_main)

            
                    add_library(GTest::gmock ALIAS gmock)

            
                    add_library(GTest::gmock_main ALIAS gmock_main)

            
                  else()

            
                    message(FATAL_ERROR "ABSL_USE_EXTERNAL_GOOGLETEST is ON and ABSL_FIND_GOOGLETEST is OFF, which means that the top-level project must build the Google Test project. However, the target gtest was not found.")

            
                  endif()

            
                endif()

            
              else()

            
                set(absl_gtest_build_dir ${CMAKE_BINARY_DIR}/googletest-build)

            
                if(ABSL_USE_GOOGLETEST_HEAD AND ABSL_GOOGLETEST_DOWNLOAD_URL)

            
                  message(FATAL_ERROR "Do not set both ABSL_USE_GOOGLETEST_HEAD and ABSL_GOOGLETEST_DOWNLOAD_URL")

            
                endif()

            
                if(ABSL_USE_GOOGLETEST_HEAD)

            
                  set(absl_gtest_download_url "https://github.com/google/googletest/archive/main.zip")

            
                elseif(ABSL_GOOGLETEST_DOWNLOAD_URL)

            
                  set(absl_gtest_download_url ${ABSL_GOOGLETEST_DOWNLOAD_URL})

            
                endif()

            
                if(absl_gtest_download_url)

            
                  set(absl_gtest_src_dir ${CMAKE_BINARY_DIR}/googletest-src)

            
                else()

            
                  set(absl_gtest_src_dir ${ABSL_LOCAL_GOOGLETEST_DIR})

            
                endif()

            
                include(CMake/Googletest/DownloadGTest.cmake)

            
              endif()

            
            endif()


            add_subdirectory(absl)


            if(ABSL_ENABLE_INSTALL)

            
              # absl:lts-remove-begin(system installation is supported for LTS releases)

            
              # We don't support system-wide installation

            
              list(APPEND SYSTEM_INSTALL_DIRS "/usr/local" "/usr" "/opt/" "/opt/local" "c:/Program Files/${PROJECT_NAME}")

            
              if(NOT DEFINED CMAKE_INSTALL_PREFIX OR CMAKE_INSTALL_PREFIX IN_LIST SYSTEM_INSTALL_DIRS)

            
                message(WARNING "\

            
              The default and system-level install directories are unsupported except in LTS \

            
              releases of Abseil.  Please set CMAKE_INSTALL_PREFIX to install Abseil in your \

            
              source or build tree directly.\

            
                ")

            
              endif()

            
              # absl:lts-remove-end


              # install as a subdirectory only

            
              install(EXPORT ${PROJECT_NAME}Targets

            
                NAMESPACE absl::

            
                DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"

            
              )


              configure_package_config_file(

            
                CMake/abslConfig.cmake.in

            
                "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"

            
                INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"

            
              )

            
              install(FILES "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"

            
                DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"

            
              )


              # Abseil only has a version in LTS releases.  This mechanism is accomplished

            
              # Abseil's internal Copybara (https://github.com/google/copybara) workflows and

            
              # isn't visible in the CMake buildsystem itself.

            
              if(absl_VERSION)

            
                write_basic_package_version_file(

            
                  "${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"

            
                  COMPATIBILITY ExactVersion

            
                )


                install(FILES "${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"

            
                  DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"

            
                )

            
              endif()  # absl_VERSION


              # Install the headers except for "options.h" which is installed separately.

            
              install(DIRECTORY absl

            
                DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}

            
                FILES_MATCHING

            
                  PATTERN "*.inc"

            
                  PATTERN "*.h"

            
                  PATTERN "options.h" EXCLUDE

            
                  PATTERN "copts" EXCLUDE

            
                  PATTERN "testdata" EXCLUDE

            
                )


              # Rewrite options.h to use the compiled ABI.

            
              file(READ "absl/base/options.h" ABSL_INTERNAL_OPTIONS_H_CONTENTS)


              # Handle features that require at least C++20.

            
              if (ABSL_INTERNAL_AT_LEAST_CXX20)

            
                foreach(FEATURE "ORDERING" "SOURCE_LOCATION")

            
                  string(REPLACE

            
                  "#define ABSL_OPTION_USE_STD_${FEATURE} 2"

            
                  "#define ABSL_OPTION_USE_STD_${FEATURE} 1"

            
                  ABSL_INTERNAL_OPTIONS_H_PINNED

            
                  "${ABSL_INTERNAL_OPTIONS_H_CONTENTS}")

            
                  set(ABSL_INTERNAL_OPTIONS_H_CONTENTS "${ABSL_INTERNAL_OPTIONS_H_PINNED}")

            
                endforeach()

            
              endif()


              # Handle features that require at least C++17.

            
              if (ABSL_INTERNAL_AT_LEAST_CXX17)

            
                foreach(FEATURE "ANY" "OPTIONAL" "STRING_VIEW" "VARIANT")

            
                  string(REPLACE

            
                  "#define ABSL_OPTION_USE_STD_${FEATURE} 2"

            
                  "#define ABSL_OPTION_USE_STD_${FEATURE} 1"

            
                  ABSL_INTERNAL_OPTIONS_H_PINNED

            
                  "${ABSL_INTERNAL_OPTIONS_H_CONTENTS}")

            
                  set(ABSL_INTERNAL_OPTIONS_H_CONTENTS "${ABSL_INTERNAL_OPTIONS_H_PINNED}")

            
                endforeach()

            
              endif()


              # Any feature that still has the value of 2 (because it was not handled above)

            
              # should be set to 0.

            
              string(REGEX REPLACE

            
                "#define ABSL_OPTION_USE_STD_([^ ]*) 2"

            
                "#define ABSL_OPTION_USE_STD_\\1 0"

            
                ABSL_INTERNAL_OPTIONS_H_PINNED

            
                "${ABSL_INTERNAL_OPTIONS_H_CONTENTS}")


              # If the file already exists, check if it matches the new contents.

            
              # This avoids writing the file if it is already up-to-date when the CMake

            
              # generation is triggered and triggering unnecessary rebuilds.

            
              set(ABSL_INTERNAL_OPTIONS_H_PINNED_NEEDS_UPDATE TRUE)

            
              if (EXISTS "${CMAKE_BINARY_DIR}/options-pinned.h")

            
                file(READ "${CMAKE_BINARY_DIR}/options-pinned.h" ABSL_INTERNAL_OPTIONS_PINNED_H_CONTENTS)

            
                if ("${ABSL_INTERNAL_OPTIONS_H_PINNED}" STREQUAL "${ABSL_INTERNAL_OPTIONS_PINNED_H_CONTENTS}")

            
                  set(ABSL_INTERNAL_OPTIONS_H_PINNED_NEEDS_UPDATE FALSE)

            
                endif()

            
              endif()


              # If the file needs an update, generate it.

            
              if (ABSL_INTERNAL_OPTIONS_H_PINNED_NEEDS_UPDATE)

            
                file(GENERATE OUTPUT "${CMAKE_BINARY_DIR}/options-pinned.h" CONTENT "${ABSL_INTERNAL_OPTIONS_H_PINNED}")

            
              endif()


              install(FILES "${CMAKE_BINARY_DIR}/options-pinned.h"

            
                     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/absl/base

            
                     RENAME "options.h")


            endif()  # ABSL_ENABLE_INSTALL
	#
	# Copyright 2017 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.
	#

	# https://github.com/google/oss-policies-info/blob/main/foundational-cxx-support-matrix.md
	# As of 2024-07-01, CMake 3.16 is the minimum supported version.
	cmake_minimum_required(VERSION 3.16)

	# Allow the user to specify the CMAKE_MSVC_DEBUG_INFORMATION_FORMAT
	if (POLICY CMP0141)
	cmake_policy(SET CMP0141 NEW)
	endif (POLICY CMP0141)

	project(absl LANGUAGES CXX)
	set(ABSL_SOVERSION 0)
	include(CTest)

	# Output directory is correct by default for most build setups. However, when
	# building Abseil as a DLL, it is important to have the DLL in the same
	# directory as the executable using it. Thus, we put all executables in a single
	# /bin directory.
	set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin)

	# when absl is included as subproject (i.e. using add_subdirectory(abseil-cpp))
	# in the source tree of a project that uses it, install rules are disabled.
	if(NOT CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
	option(ABSL_ENABLE_INSTALL "Enable install rule" OFF)
	else()
	option(ABSL_ENABLE_INSTALL "Enable install rule" ON)
	endif()

	set(CMAKE_INSTALL_RPATH "$ORIGIN")
	set(CMAKE_INSTALL_RPATH_USE_LINK_PATH ON)
	set(CMAKE_BUILD_RPATH_USE_ORIGIN ON)

	option(ABSL_PROPAGATE_CXX_STD
	"Use CMake C++ standard meta features (e.g. cxx_std_17) that propagate to targets that link to Abseil"
	ON)

	option(ABSL_USE_SYSTEM_INCLUDES
	"Silence warnings in Abseil headers by marking them as SYSTEM includes"
	OFF)

	list(APPEND CMAKE_MODULE_PATH
	${CMAKE_CURRENT_LIST_DIR}/CMake
	${CMAKE_CURRENT_LIST_DIR}/absl/copts
	)

	option(ABSL_MSVC_STATIC_RUNTIME
	"Link static runtime libraries"
	OFF)
	if(ABSL_MSVC_STATIC_RUNTIME)
	set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
	else()
	set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>DLL")
	endif()

	include(CMakePackageConfigHelpers)
	include(GNUInstallDirs)
	include(AbseilDll)
	include(AbseilHelpers)


	##
	## Using absl targets
	##
	## all public absl targets are
	## exported with the absl:: prefix
	##
	## e.g absl::base absl::synchronization absl::strings ....
	##
	## DO NOT rely on the internal targets outside of the prefix


	# include current path
	list(APPEND ABSL_COMMON_INCLUDE_DIRS ${CMAKE_CURRENT_SOURCE_DIR})

	if("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
	set(ABSL_USING_CLANG ON)
	else()
	set(ABSL_USING_CLANG OFF)
	endif()

	# find dependencies
	## pthread
	find_package(Threads REQUIRED)

	include(CMakeDependentOption)

	option(ABSL_BUILD_TESTING
	"If ON, Abseil will build all of Abseil's own tests." OFF)

	option(ABSL_BUILD_TEST_HELPERS
	"If ON, Abseil will build libraries that you can use to write tests against Abseil code. This option requires that Abseil is configured to use GoogleTest."
	OFF)

	option(ABSL_USE_EXTERNAL_GOOGLETEST
	"If ON, Abseil will assume that the targets for GoogleTest are already provided by the including project. This makes sense when Abseil is used with add_subdirectory." OFF)

	cmake_dependent_option(ABSL_FIND_GOOGLETEST
	"If ON, Abseil will use find_package(GTest) rather than assuming that GoogleTest is already provided by the including project."
	ON
	"ABSL_USE_EXTERNAL_GOOGLETEST"
	OFF)


	option(ABSL_USE_GOOGLETEST_HEAD
	"If ON, abseil will download HEAD from GoogleTest at config time." OFF)

	set(ABSL_GOOGLETEST_DOWNLOAD_URL "" CACHE STRING "If set, download GoogleTest from this URL")

	set(ABSL_LOCAL_GOOGLETEST_DIR "/usr/src/googletest" CACHE PATH
	"If ABSL_USE_GOOGLETEST_HEAD is OFF and ABSL_GOOGLETEST_URL is not set, specifies the directory of a local GoogleTest checkout."
	)

	option(ABSL_BUILD_MONOLITHIC_SHARED_LIBS
	"Build Abseil as a single shared library (always enabled for Windows)"
	OFF
	)
	if(NOT BUILD_SHARED_LIBS AND ABSL_BUILD_MONOLITHIC_SHARED_LIBS)
	message(WARNING "Not building a shared library because BUILD_SHARED_LIBS is not set. Ignoring ABSL_BUILD_MONOLITHIC_SHARED_LIBS.")
	endif()

	if((BUILD_TESTING AND ABSL_BUILD_TESTING) OR ABSL_BUILD_TEST_HELPERS)
	if (ABSL_USE_EXTERNAL_GOOGLETEST)
	if (ABSL_FIND_GOOGLETEST)
	find_package(GTest REQUIRED)
	elseif(NOT TARGET GTest::gtest)
	if(TARGET gtest)
	# When Google Test is included directly rather than through find_package, the aliases are missing.
	add_library(GTest::gtest ALIAS gtest)
	add_library(GTest::gtest_main ALIAS gtest_main)
	add_library(GTest::gmock ALIAS gmock)
	add_library(GTest::gmock_main ALIAS gmock_main)
	else()
	message(FATAL_ERROR "ABSL_USE_EXTERNAL_GOOGLETEST is ON and ABSL_FIND_GOOGLETEST is OFF, which means that the top-level project must build the Google Test project. However, the target gtest was not found.")
	endif()
	endif()
	else()
	set(absl_gtest_build_dir ${CMAKE_BINARY_DIR}/googletest-build)
	if(ABSL_USE_GOOGLETEST_HEAD AND ABSL_GOOGLETEST_DOWNLOAD_URL)
	message(FATAL_ERROR "Do not set both ABSL_USE_GOOGLETEST_HEAD and ABSL_GOOGLETEST_DOWNLOAD_URL")
	endif()
	if(ABSL_USE_GOOGLETEST_HEAD)
	set(absl_gtest_download_url "https://github.com/google/googletest/archive/main.zip")
	elseif(ABSL_GOOGLETEST_DOWNLOAD_URL)
	set(absl_gtest_download_url ${ABSL_GOOGLETEST_DOWNLOAD_URL})
	endif()
	if(absl_gtest_download_url)
	set(absl_gtest_src_dir ${CMAKE_BINARY_DIR}/googletest-src)
	else()
	set(absl_gtest_src_dir ${ABSL_LOCAL_GOOGLETEST_DIR})
	endif()
	include(CMake/Googletest/DownloadGTest.cmake)
	endif()
	endif()

	add_subdirectory(absl)

	if(ABSL_ENABLE_INSTALL)
	# absl:lts-remove-begin(system installation is supported for LTS releases)
	# We don't support system-wide installation
	list(APPEND SYSTEM_INSTALL_DIRS "/usr/local" "/usr" "/opt/" "/opt/local" "c:/Program Files/${PROJECT_NAME}")
	if(NOT DEFINED CMAKE_INSTALL_PREFIX OR CMAKE_INSTALL_PREFIX IN_LIST SYSTEM_INSTALL_DIRS)
	message(WARNING "\
	The default and system-level install directories are unsupported except in LTS \
	releases of Abseil. Please set CMAKE_INSTALL_PREFIX to install Abseil in your \
	source or build tree directly.\
	")
	endif()
	# absl:lts-remove-end

	# install as a subdirectory only
	install(EXPORT ${PROJECT_NAME}Targets
	NAMESPACE absl::
	DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
	)

	configure_package_config_file(
	CMake/abslConfig.cmake.in
	"${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
	INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
	)
	install(FILES "${PROJECT_BINARY_DIR}/${PROJECT_NAME}Config.cmake"
	DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
	)

	# Abseil only has a version in LTS releases. This mechanism is accomplished
	# Abseil's internal Copybara (https://github.com/google/copybara) workflows and
	# isn't visible in the CMake buildsystem itself.
	if(absl_VERSION)
	write_basic_package_version_file(
	"${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
	COMPATIBILITY ExactVersion
	)

	install(FILES "${PROJECT_BINARY_DIR}/${PROJECT_NAME}ConfigVersion.cmake"
	DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
	)
	endif() # absl_VERSION

	# Install the headers except for "options.h" which is installed separately.
	install(DIRECTORY absl
	DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
	FILES_MATCHING
	PATTERN "*.inc"
	PATTERN "*.h"
	PATTERN "options.h" EXCLUDE
	PATTERN "copts" EXCLUDE
	PATTERN "testdata" EXCLUDE
	)

	# Rewrite options.h to use the compiled ABI.
	file(READ "absl/base/options.h" ABSL_INTERNAL_OPTIONS_H_CONTENTS)

	# Handle features that require at least C++20.
	if (ABSL_INTERNAL_AT_LEAST_CXX20)
	foreach(FEATURE "ORDERING" "SOURCE_LOCATION")
	string(REPLACE
	"#define ABSL_OPTION_USE_STD_${FEATURE} 2"
	"#define ABSL_OPTION_USE_STD_${FEATURE} 1"
	ABSL_INTERNAL_OPTIONS_H_PINNED
	"${ABSL_INTERNAL_OPTIONS_H_CONTENTS}")
	set(ABSL_INTERNAL_OPTIONS_H_CONTENTS "${ABSL_INTERNAL_OPTIONS_H_PINNED}")
	endforeach()
	endif()

	# Handle features that require at least C++17.
	if (ABSL_INTERNAL_AT_LEAST_CXX17)
	foreach(FEATURE "ANY" "OPTIONAL" "STRING_VIEW" "VARIANT")
	string(REPLACE
	"#define ABSL_OPTION_USE_STD_${FEATURE} 2"
	"#define ABSL_OPTION_USE_STD_${FEATURE} 1"
	ABSL_INTERNAL_OPTIONS_H_PINNED
	"${ABSL_INTERNAL_OPTIONS_H_CONTENTS}")
	set(ABSL_INTERNAL_OPTIONS_H_CONTENTS "${ABSL_INTERNAL_OPTIONS_H_PINNED}")
	endforeach()
	endif()

	# Any feature that still has the value of 2 (because it was not handled above)
	# should be set to 0.
	string(REGEX REPLACE
	"#define ABSL_OPTION_USE_STD_([^ ]*) 2"
	"#define ABSL_OPTION_USE_STD_\\1 0"
	ABSL_INTERNAL_OPTIONS_H_PINNED
	"${ABSL_INTERNAL_OPTIONS_H_CONTENTS}")

	# If the file already exists, check if it matches the new contents.
	# This avoids writing the file if it is already up-to-date when the CMake
	# generation is triggered and triggering unnecessary rebuilds.
	set(ABSL_INTERNAL_OPTIONS_H_PINNED_NEEDS_UPDATE TRUE)
	if (EXISTS "${CMAKE_BINARY_DIR}/options-pinned.h")
	file(READ "${CMAKE_BINARY_DIR}/options-pinned.h" ABSL_INTERNAL_OPTIONS_PINNED_H_CONTENTS)
	if ("${ABSL_INTERNAL_OPTIONS_H_PINNED}" STREQUAL "${ABSL_INTERNAL_OPTIONS_PINNED_H_CONTENTS}")
	set(ABSL_INTERNAL_OPTIONS_H_PINNED_NEEDS_UPDATE FALSE)
	endif()
	endif()

	# If the file needs an update, generate it.
	if (ABSL_INTERNAL_OPTIONS_H_PINNED_NEEDS_UPDATE)
	file(GENERATE OUTPUT "${CMAKE_BINARY_DIR}/options-pinned.h" CONTENT "${ABSL_INTERNAL_OPTIONS_H_PINNED}")
	endif()

	install(FILES "${CMAKE_BINARY_DIR}/options-pinned.h"
	DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/absl/base
	RENAME "options.h")

	endif() # ABSL_ENABLE_INSTALL