CMake/Modules/CheckVariableExists.cmake

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#.rst:
# CheckVariableExists
# -------------------
#
# Check if the variable exists.
#
# ::
#
# CHECK_VARIABLE_EXISTS(VAR VARIABLE)
#
#
#
# ::
#
# VAR - the name of the variable
# VARIABLE - variable to store the result
#
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#
#
# This macro is only for C variables.
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#
# 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 ${VAR} exists failed with the following output:\n"
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"${OUTPUT}\n\n")
endif()
endif()
endmacro()