# - Check if the variable exists. # CHECK_VARIABLE_EXISTS(VAR VARIABLE) # # VAR - the name of the variable # VARIABLE - variable to store the result # # This macro is only for C variables. # # 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_LIBRARIES = list of libraries to link #============================================================================= # Copyright 2002-2009 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_VARIABLE_EXISTS VAR VARIABLE) if("${VARIABLE}" MATCHES "^${VARIABLE}$") set(MACRO_CHECK_VARIABLE_DEFINITIONS "-DCHECK_VARIABLE_EXISTS=${VAR} ${CMAKE_REQUIRED_FLAGS}") message(STATUS "Looking for ${VAR}") if(CMAKE_REQUIRED_LIBRARIES) set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES}) else() set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES) endif() try_compile(${VARIABLE} ${CMAKE_BINARY_DIR} ${CMAKE_ROOT}/Modules/CheckVariableExists.c COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS} ${CHECK_VARIABLE_EXISTS_ADD_LIBRARIES} CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_VARIABLE_DEFINITIONS} OUTPUT_VARIABLE OUTPUT) if(${VARIABLE}) set(${VARIABLE} 1 CACHE INTERNAL "Have variable ${VAR}") message(STATUS "Looking for ${VAR} - found") file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log "Determining if the variable ${VAR} exists passed with the following output:\n" "${OUTPUT}\n\n") else() set(${VARIABLE} "" CACHE INTERNAL "Have variable ${VAR}") message(STATUS "Looking for ${VAR} - not found") file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log "Determining if the variable ${VAR} exists failed with the following output:\n" "${OUTPUT}\n\n") endif() endif() endmacro()