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.
 #

 # Most widely used distributions have cmake 3.5 or greater available as of March
 # 2019.  A notable exception is RHEL-7 (CentOS7).  You can install a current
 # version of CMake by first installing Extra Packages for Enterprise Linux
 # (https://fedoraproject.org/wiki/EPEL#Extra_Packages_for_Enterprise_Linux_.28EPEL.29)
 # and then issuing `yum install cmake3` on the command line.
 cmake_minimum_required(VERSION 3.5)

 # Compiler id for Apple Clang is now AppleClang.
 if (POLICY CMP0025)
   cmake_policy(SET CMP0025 NEW)
 endif (POLICY CMP0025)

 # if command can use IN_LIST
 if (POLICY CMP0057)
   cmake_policy(SET CMP0057 NEW)
 endif (POLICY CMP0057)

 # Project version variables are the empty string if version is unspecified
 if (POLICY CMP0048)
   cmake_policy(SET CMP0048 NEW)
 endif (POLICY CMP0048)

 # option() honor variables
 if (POLICY CMP0077)
   cmake_policy(SET CMP0077 NEW)
 endif (POLICY CMP0077)

 # Allow the user to specify the MSVC runtime
 if (POLICY CMP0091)
   cmake_policy(SET CMP0091 NEW)
 endif (POLICY CMP0091)

 project(absl LANGUAGES CXX VERSION 20220623)
 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()

 option(ABSL_PROPAGATE_CXX_STD
   "Use CMake C++ standard meta features (e.g. cxx_std_11) that propagate to targets that link to Abseil"
   OFF)  # TODO: Default to ON for CMake 3.8 and greater.
 if((${CMAKE_VERSION} VERSION_GREATER_EQUAL 3.8) AND (NOT ABSL_PROPAGATE_CXX_STD))
   message(WARNING "A future Abseil release will default ABSL_PROPAGATE_CXX_STD to ON for CMake 3.8 and up. We recommend enabling this option to ensure your project still builds correctly.")
 endif()

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

 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_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."
   )

 if(BUILD_TESTING AND ABSL_BUILD_TESTING)
   ## check targets
   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()

   check_target(GTest::gtest)
   check_target(GTest::gtest_main)
   check_target(GTest::gmock)
   check_target(GTest::gmock_main)
 endif()

 add_subdirectory(absl)

 if(ABSL_ENABLE_INSTALL)


   # 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(DIRECTORY absl
     DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
     FILES_MATCHING
       PATTERN "*.inc"
       PATTERN "*.h"
       PATTERN "copts" EXCLUDE
       PATTERN "testdata" EXCLUDE
     )
 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.
	#

	# Most widely used distributions have cmake 3.5 or greater available as of March
	# 2019. A notable exception is RHEL-7 (CentOS7). You can install a current
	# version of CMake by first installing Extra Packages for Enterprise Linux
	# (https://fedoraproject.org/wiki/EPEL#Extra_Packages_for_Enterprise_Linux_.28EPEL.29)
	# and then issuing `yum install cmake3` on the command line.
	cmake_minimum_required(VERSION 3.5)

	# Compiler id for Apple Clang is now AppleClang.
	if (POLICY CMP0025)
	cmake_policy(SET CMP0025 NEW)
	endif (POLICY CMP0025)

	# if command can use IN_LIST
	if (POLICY CMP0057)
	cmake_policy(SET CMP0057 NEW)
	endif (POLICY CMP0057)

	# Project version variables are the empty string if version is unspecified
	if (POLICY CMP0048)
	cmake_policy(SET CMP0048 NEW)
	endif (POLICY CMP0048)

	# option() honor variables
	if (POLICY CMP0077)
	cmake_policy(SET CMP0077 NEW)
	endif (POLICY CMP0077)

	# Allow the user to specify the MSVC runtime
	if (POLICY CMP0091)
	cmake_policy(SET CMP0091 NEW)
	endif (POLICY CMP0091)

	project(absl LANGUAGES CXX VERSION 20220623)
	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()

	option(ABSL_PROPAGATE_CXX_STD
	"Use CMake C++ standard meta features (e.g. cxx_std_11) that propagate to targets that link to Abseil"
	OFF) # TODO: Default to ON for CMake 3.8 and greater.
	if((${CMAKE_VERSION} VERSION_GREATER_EQUAL 3.8) AND (NOT ABSL_PROPAGATE_CXX_STD))
	message(WARNING "A future Abseil release will default ABSL_PROPAGATE_CXX_STD to ON for CMake 3.8 and up. We recommend enabling this option to ensure your project still builds correctly.")
	endif()

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

	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_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."
	)

	if(BUILD_TESTING AND ABSL_BUILD_TESTING)
	## check targets
	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()

	check_target(GTest::gtest)
	check_target(GTest::gtest_main)
	check_target(GTest::gmock)
	check_target(GTest::gmock_main)
	endif()

	add_subdirectory(absl)

	if(ABSL_ENABLE_INSTALL)


	# 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(DIRECTORY absl
	DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
	FILES_MATCHING
	PATTERN "*.inc"
	PATTERN "*.h"
	PATTERN "copts" EXCLUDE
	PATTERN "testdata" EXCLUDE
	)
	endif() # ABSL_ENABLE_INSTALL