Add CheckLanguage module

Define a "check_language(<lang>)" macro to test whether <lang> can be
enabled.  Cache the result in CMAKE_<lang>_COMPILER.  Add a test case
covering expected results.
This commit is contained in:
Brad King 2012-02-08 10:48:34 -05:00
parent 7dcfd9aaf6
commit 5db99e8708
3 changed files with 89 additions and 0 deletions

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@ -0,0 +1,65 @@
# - Check if a language can be enabled
# Usage:
# check_language(<lang>)
# where <lang> is a language that may be passed to enable_language()
# such as "Fortran". If CMAKE_<lang>_COMPILER is already defined the
# check does nothing. Otherwise it tries enabling the language in a
# test project. The result is cached in CMAKE_<lang>_COMPILER as the
# compiler that was found, or NOTFOUND if the language cannot be enabled.
#
# Example:
# check_language(Fortran)
# if(CMAKE_Fortran_COMPILER)
# enable_language(Fortran)
# else()
# message(STATUS "No Fortran support")
# endif()
#=============================================================================
# Copyright 2009-2012 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_language lang)
if(NOT DEFINED CMAKE_${lang}_COMPILER)
set(_desc "Looking for a ${lang} compiler")
message(STATUS ${_desc})
file(REMOVE_RECURSE ${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/Check${lang})
file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/Check${lang}/CMakeLists.txt"
"cmake_minimum_required(VERSION 2.8)
project(Check${lang} ${lang})
file(WRITE \"\${CMAKE_CURRENT_BINARY_DIR}/result.cmake\"
\"set(CMAKE_${lang}_COMPILER \\\"\${CMAKE_${lang}_COMPILER}\\\")\\n\"
)
")
execute_process(
WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/Check${lang}
COMMAND ${CMAKE_COMMAND} . -G ${CMAKE_GENERATOR}
OUTPUT_VARIABLE output
ERROR_VARIABLE output
RESULT_VARIABLE result
)
include(${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/Check${lang}/result.cmake OPTIONAL)
if(CMAKE_${lang}_COMPILER AND "${result}" STREQUAL "0")
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeOutput.log
"${_desc} passed with the following output:\n"
"${output}\n")
else()
set(CMAKE_${lang}_COMPILER NOTFOUND)
file(APPEND ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"${_desc} failed with the following output:\n"
"${output}\n")
endif()
message(STATUS "${_desc} - ${CMAKE_${lang}_COMPILER}")
set(CMAKE_${lang}_COMPILER "${CMAKE_${lang}_COMPILER}" CACHE FILEPATH "${lang} compiler")
mark_as_advanced(CMAKE_${lang}_COMPILER)
endif()
endmacro()

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@ -17,6 +17,8 @@ add_CMakeOnly_test(CheckCXXSymbolExists)
add_CMakeOnly_test(CheckCXXCompilerFlag)
add_CMakeOnly_test(CheckLanguage)
add_CMakeOnly_test(AllFindModules)
add_CMakeOnly_test(TargetScope)

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@ -0,0 +1,22 @@
cmake_minimum_required (VERSION 2.8)
project(CheckLanguage NONE)
include(CheckLanguage)
set(langs )
set(expect_C 1)
set(expect_CXX 1)
unset(expect_Fortran)
set(expect_NoSuchLanguage 0)
foreach(lang C CXX Fortran NoSuchLanguage)
check_language(${lang})
if(NOT DEFINED CMAKE_${lang}_COMPILER)
message(FATAL_ERROR "check_language(${lang}) did not set result")
endif()
if(DEFINED expect_${lang})
if(expect_${lang} AND NOT CMAKE_${lang}_COMPILER)
message(FATAL_ERROR "check_language(${lang}) should not fail!")
elseif(NOT expect_${lang} AND CMAKE_${lang}_COMPILER)
message(FATAL_ERROR "check_language(${lang}) should not succeed!")
endif()
endif()
endforeach()