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86 lines
2.9 KiB
86 lines
2.9 KiB
# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
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# file Copyright.txt or https://cmake.org/licensing for details.
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#[=======================================================================[.rst:
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CheckVariableExists
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-------------------
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Check if the variable exists.
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.. command:: CHECK_VARIABLE_EXISTS
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.. code-block:: cmake
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CHECK_VARIABLE_EXISTS(VAR VARIABLE)
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::
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VAR - the name of the variable
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VARIABLE - variable to store the result
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Will be created as an internal cache variable.
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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
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the way the check is run:
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::
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CMAKE_REQUIRED_FLAGS = string of compile command line flags
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CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
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CMAKE_REQUIRED_LINK_OPTIONS = list of options to pass to link command
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CMAKE_REQUIRED_LIBRARIES = list of libraries to link
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CMAKE_REQUIRED_QUIET = execute quietly without messages
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#]=======================================================================]
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include_guard(GLOBAL)
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macro(CHECK_VARIABLE_EXISTS VAR VARIABLE)
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if(NOT DEFINED "${VARIABLE}")
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set(MACRO_CHECK_VARIABLE_DEFINITIONS
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"-DCHECK_VARIABLE_EXISTS=${VAR} ${CMAKE_REQUIRED_FLAGS}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${VAR}")
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endif()
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if(CMAKE_REQUIRED_LINK_OPTIONS)
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set(CHECK_VARIABLE_EXISTS_ADD_LINK_OPTIONS
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LINK_OPTIONS ${CMAKE_REQUIRED_LINK_OPTIONS})
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else()
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set(CHECK_VARIABLE_EXISTS_ADD_LINK_OPTIONS)
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endif()
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if(CMAKE_REQUIRED_LIBRARIES)
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set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES
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LINK_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
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else()
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set(CHECK_VARIABLE_EXISTS_ADD_LIBRARIES)
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endif()
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try_compile(${VARIABLE}
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${CMAKE_BINARY_DIR}
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${CMAKE_ROOT}/Modules/CheckVariableExists.c
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COMPILE_DEFINITIONS ${CMAKE_REQUIRED_DEFINITIONS}
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${CHECK_VARIABLE_EXISTS_ADD_LINK_OPTIONS}
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${CHECK_VARIABLE_EXISTS_ADD_LIBRARIES}
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CMAKE_FLAGS -DCOMPILE_DEFINITIONS:STRING=${MACRO_CHECK_VARIABLE_DEFINITIONS}
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OUTPUT_VARIABLE OUTPUT)
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if(${VARIABLE})
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set(${VARIABLE} 1 CACHE INTERNAL "Have variable ${VAR}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${VAR} - found")
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endif()
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file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
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"Determining if the variable ${VAR} exists passed with the following output:\n"
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"${OUTPUT}\n\n")
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else()
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set(${VARIABLE} "" CACHE INTERNAL "Have variable ${VAR}")
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if(NOT CMAKE_REQUIRED_QUIET)
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message(STATUS "Looking for ${VAR} - not found")
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endif()
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file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
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"Determining if the variable ${VAR} exists failed with the following output:\n"
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"${OUTPUT}\n\n")
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endif()
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endif()
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endmacro()
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