# Distributed under the OSI-approved BSD 3-Clause License. See accompanying # file Copyright.txt or https://cmake.org/licensing for details. #[=======================================================================[.rst: CheckSymbolExists ----------------- Provides a macro to check if a symbol exists as a function, variable, or macro in ``C``. .. command:: check_symbol_exists :: check_symbol_exists( ) Check that the ```` is available after including given header ```` and store the result in a ````. Specify the list of files in one argument as a semicolon-separated list. ```` will be created as an internal cache variable. If the header files define the symbol as a macro it is considered available and assumed to work. If the header files declare the symbol as a function or variable then the symbol must also be available for linking (so intrinsics may not be detected). If the symbol is a type, enum value, or intrinsic it will not be recognized (consider using :module:`CheckTypeSize` or :module:`CheckCSourceCompiles`). If the check needs to be done in C++, consider using :module:`CheckCXXSymbolExists` instead. The following variables may be set before calling this macro to modify the way the check is run: ``CMAKE_REQUIRED_FLAGS`` string of compile command line flags ``CMAKE_REQUIRED_DEFINITIONS`` list of macros to define (-DFOO=bar) ``CMAKE_REQUIRED_INCLUDES`` list of include directories ``CMAKE_REQUIRED_LIBRARIES`` list of libraries to link ``CMAKE_REQUIRED_QUIET`` execute quietly without messages #]=======================================================================] include_guard(GLOBAL) cmake_policy(PUSH) cmake_policy(SET CMP0054 NEW) # if() quoted variables not dereferenced macro(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE) if(CMAKE_C_COMPILER_LOADED) __CHECK_SYMBOL_EXISTS_IMPL("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c" "${SYMBOL}" "${FILES}" "${VARIABLE}" ) elseif(CMAKE_CXX_COMPILER_LOADED) __CHECK_SYMBOL_EXISTS_IMPL("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.cxx" "${SYMBOL}" "${FILES}" "${VARIABLE}" ) else() message(FATAL_ERROR "CHECK_SYMBOL_EXISTS needs either C or CXX language enabled") endif() endmacro() macro(__CHECK_SYMBOL_EXISTS_IMPL SOURCEFILE SYMBOL FILES VARIABLE) if(NOT DEFINED "${VARIABLE}" OR "x${${VARIABLE}}" STREQUAL "x${VARIABLE}") set(CMAKE_CONFIGURABLE_FILE_CONTENT "/* */\n") set(MACRO_CHECK_SYMBOL_EXISTS_FLAGS ${CMAKE_REQUIRED_FLAGS}) if(CMAKE_REQUIRED_LIBRARIES) set(CHECK_SYMBOL_EXISTS_LIBS LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES}) else() set(CHECK_SYMBOL_EXISTS_LIBS) endif() if(CMAKE_REQUIRED_INCLUDES) set(CMAKE_SYMBOL_EXISTS_INCLUDES "-DINCLUDE_DIRECTORIES:STRING=${CMAKE_REQUIRED_INCLUDES}") else() set(CMAKE_SYMBOL_EXISTS_INCLUDES) endif() foreach(FILE ${FILES}) string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT "#include <${FILE}>\n") endforeach() string(APPEND CMAKE_CONFIGURABLE_FILE_CONTENT "\nint main(int argc, char** argv)\n{\n (void)argv;\n#ifndef ${SYMBOL}\n return ((int*)(&${SYMBOL}))[argc];\n#else\n (void)argc;\n return 0;\n#endif\n}\n") configure_file("${CMAKE_ROOT}/Modules/CMakeConfigurableFile.in" "${SOURCEFILE}" @ONLY) if(NOT CMAKE_REQUIRED_QUIET) message(STATUS "Looking for ${SYMBOL}") endif() try_compile(${VARIABLE} ${CMAKE_BINARY_DIR} "${SOURCEFILE}" COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} ${CHECK_SYMBOL_EXISTS_LIBS} CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_SYMBOL_EXISTS_FLAGS} "${CMAKE_SYMBOL_EXISTS_INCLUDES}" OUTPUT_VARIABLE OUTPUT) if(${VARIABLE}) if(NOT CMAKE_REQUIRED_QUIET) message(STATUS "Looking for ${SYMBOL} - found") endif() set(${VARIABLE} 1 CACHE INTERNAL "Have symbol ${SYMBOL}") file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log "Determining if the ${SYMBOL} " "exist passed with the following output:\n" "${OUTPUT}\nFile ${SOURCEFILE}:\n" "${CMAKE_CONFIGURABLE_FILE_CONTENT}\n") else() if(NOT CMAKE_REQUIRED_QUIET) message(STATUS "Looking for ${SYMBOL} - not found") endif() set(${VARIABLE} "" CACHE INTERNAL "Have symbol ${SYMBOL}") file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log "Determining if the ${SYMBOL} " "exist failed with the following output:\n" "${OUTPUT}\nFile ${SOURCEFILE}:\n" "${CMAKE_CONFIGURABLE_FILE_CONTENT}\n") endif() endif() endmacro() cmake_policy(POP)