CMake/Modules/CheckSymbolExists.cmake
Sebastian Leske 908c74399a Help: Document that the CHECK_* macros create cache variables
Otherwise callers may expect to be able to re-use result variables.
2014-09-11 08:55:26 -04:00

114 lines
4.5 KiB
CMake

#.rst:
# CheckSymbolExists
# -----------------
#
# Check if a symbol exists as a function, variable, or macro
#
# CHECK_SYMBOL_EXISTS(<symbol> <files> <variable>)
#
# Check that the <symbol> is available after including given header
# <files> and store the result in a <variable>. Specify the list of
# files in one argument as a semicolon-separated list.
# <variable> 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. If the symbol is a type or enum value it will not be
# recognized (consider using CheckTypeSize or CheckCSourceCompiles). If
# the check needs to be done in C++, consider using
# CHECK_CXX_SYMBOL_EXISTS(), which does the same as
# CHECK_SYMBOL_EXISTS(), but in C++.
#
# 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
#=============================================================================
# Copyright 2003-2011 Kitware, Inc.
#
# Distributed under the OSI-approved BSD License (the "License");
# see accompanying file Copyright.txt for details.
#
# This software is distributed WITHOUT ANY WARRANTY; without even the
# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
# See the License for more information.
#=============================================================================
# (To distribute this file outside of CMake, substitute the full
# License text for the above reference.)
macro(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
_CHECK_SYMBOL_EXISTS("${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/CheckSymbolExists.c" "${SYMBOL}" "${FILES}" "${VARIABLE}" )
endmacro()
macro(_CHECK_SYMBOL_EXISTS SOURCEFILE SYMBOL FILES VARIABLE)
if(NOT DEFINED "${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 ${FILES})
set(CMAKE_CONFIGURABLE_FILE_CONTENT
"${CMAKE_CONFIGURABLE_FILE_CONTENT}#include <${FILE}>\n")
endforeach()
set(CMAKE_CONFIGURABLE_FILE_CONTENT
"${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()