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# Copyright (C) 2011-2020 Daniel Scharrer
#
# This software is provided 'as-is', without any express or implied
# warranty. In no event will the author(s) be held liable for any damages
# arising from the use of this software.
#
# Permission is granted to anyone to use this software for any purpose,
# including commercial applications, and to alter it and redistribute it
# freely, subject to the following restrictions:
#
# 1. The origin of this software must not be misrepresented; you must not
# claim that you wrote the original software. If you use this software
# in a product, an acknowledgment in the product documentation would be
# appreciated but is not required.
# 2. Altered source versions must be plainly marked as such, and must not be
# misrepresented as being the original software.
# 3. This notice may not be removed or altered from any source distribution.
# Note: In CMake before 3.0 set(var "" PARENT_SCOPE) *unsets* the variable in the
# parent scope instead of setting it to the empty string.
# This means if(var STREQUAL "") will be false since var is not defined and thus not expanded.
function(check_compile RESULT FILE FLAG TYPE)
string(REGEX REPLACE "[^a-zA-Z0-9_][^a-zA-Z0-9_]*" "-" cachevar "${TYPE}-${FLAG}")
set(cahevar "CHECK_COMPILE_${cahevar}")
if(DEFINED ${cachevar})
if(${cachevar})
set(${RESULT} "${FLAG}" PARENT_SCOPE)
else()
set(${RESULT} "" PARENT_SCOPE)
endif()
return()
endif()
string(REGEX REPLACE "[^a-zA-Z0-9]" "\\\\\\0" escaped_flag ${FLAG} )
# CMake already has a check_cxx_compiler_flag macro in CheckCXXCompilerFlag, but
# it prints the result variable in the output (which is ugly!) and also uses it
# as a key to cache checks - so it would need to be unique for each flag.
# Unfortunately it also naively pastes the variable name inside a regexp so
# if we tried to use the flag itself in the variable name it will fail for -std=c++11.
# But we can at least use the expressions for warnings from that macro (and more):
set(fail_regexps
"warning:" # general
"unrecognized .*option" # GNU
"${escaped_flag}.* not supported" # GNU
"unknown .*option" # Clang
"ignoring unknown option" # MSVC
"warning D9002" # MSVC, any lang
"warning #[0-9]*:" # Intel
"option.*not supported" # Intel
"invalid argument .*option" # Intel
"ignoring option .*argument required" # Intel
"command line warning" # Intel
"[Uu]nknown option" # HP
"[Ww]arning: [Oo]ption" # SunPro
"command option .* is not recognized" # XL
"not supported in this configuration; ignored" # AIX
"File with unknown suffix passed to linker" # PGI
"WARNING: unknown flag:" # Open64
)
# Set the flags to check
set(old_CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(old_CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS}")
set(old_CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS}")
set(old_CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS}")
if(TYPE STREQUAL "linker flag")
set(CMAKE_EXE_LINKER_FLAGS "${old_CMAKE_EXE_LINKER_FLAGS} ${FLAG}")
set(CMAKE_SHARED_LINKER_FLAGS "${old_CMAKE_SHARED_LINKER_FLAGS} ${FLAG}")
set(CMAKE_MODULE_LINKER_FLAGS "${old_CMAKE_MODULE_LINKER_FLAGS} ${FLAG}")
elseif(TYPE STREQUAL "compiler flag")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${FLAG}")
endif()
# Check if we can compile and link a simple file with the new flags
try_compile(
check_compiler_flag ${PROJECT_BINARY_DIR} ${FILE}
CMAKE_FLAGS "-DCMAKE_CXX_FLAGS:STRING=${CMAKE_CXX_FLAGS}"
"-DCMAKE_EXE_LINKER_FLAGS:STRING=${CMAKE_EXE_LINKER_FLAGS}"
"-DCMAKE_SHARED_LINKER_FLAGS:STRING=${CMAKE_SHARED_LINKER_FLAGS}"
"-DCMAKE_MODULE_LINKER_FLAGS:STRING=${CMAKE_MODULE_LINKER_FLAGS}"
OUTPUT_VARIABLE ERRORLOG
)
# Restore the old flags
set(CMAKE_CXX_FLAGS "${old_CMAKE_CXX_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "${old_CMAKE_EXE_LINKER_FLAGS}")
set(CMAKE_SHARED_LINKER_FLAGS "${old_CMAKE_SHARED_LINKER_FLAGS}")
set(CMAKE_MODULE_LINKER_FLAGS "${old_CMAKE_MODULE_LINKER_FLAGS}")
if(NOT check_compiler_flag)
message(STATUS "Checking ${TYPE}: ${FLAG} - unsupported")
set(${RESULT} "" PARENT_SCOPE)
set("${cachevar}" 0 CACHE INTERNAL "...")
else()
set(has_warning 0)
foreach(expr IN LISTS fail_regexps)
if("${ERRORLOG}" MATCHES "${expr}")
set(has_warning 1)
endif()
endforeach()
if(has_warning)
message(STATUS "Checking ${TYPE}: ${FLAG} - unsupported (warning)")
set(${RESULT} "" PARENT_SCOPE)
set("${cachevar}" 0 CACHE INTERNAL "...")
else()
message(STATUS "Checking ${TYPE}: ${FLAG}")
set(${RESULT} "${FLAG}" PARENT_SCOPE)
set("${cachevar}" 1 CACHE INTERNAL "...")
endif()
endif()
endfunction(check_compile)
function(check_flag RESULT FLAG TYPE)
set(compile_test_file "${CMAKE_CURRENT_BINARY_DIR}/compile_flag_test.cpp")
if(MSVC)
file(WRITE ${compile_test_file} "int main(){ return 0; }\n")
else()
file(WRITE ${compile_test_file} "__attribute__((const)) int main(){ return 0; }\n")
endif()
check_compile(result "${compile_test_file}" "${FLAG}" "${TYPE} flag")
set(${RESULT} "${result}" PARENT_SCOPE)
endfunction(check_flag)
macro(strip_warning_flags VAR)
string(REGEX REPLACE "(^| )\\-(W[^ l][^ ]*|Wl[^,][^ ]*|pedantic)" "" ${VAR} "${${VAR}}")
endmacro()
function(check_builtin RESULT EXPR)
string(REGEX REPLACE "[^a-zA-Z0-9_][^a-zA-Z0-9_]*" "-" check "${EXPR}")
string(REGEX REPLACE "_*\\-_*" "-" check "${check}")
string(REGEX REPLACE "^[_\\-]+" "" check "${check}")
string(REGEX REPLACE "[_\\-]+$" "" check "${check}")
set(compile_test_file "${CMAKE_CURRENT_BINARY_DIR}/check-builtin-${check}.cpp")
string(REGEX MATCH "[a-zA-Z_][a-zA-Z_0-9]*" type "${EXPR}")
file(WRITE ${compile_test_file} "__attribute__((const)) int main(){ (void)(${EXPR}); return 0; }\n")
set(old_CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
set(old_CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS}")
strip_warning_flags(CMAKE_CXX_FLAGS)
strip_warning_flags(CMAKE_EXE_LINKER_FLAGS)
check_compile(result "${compile_test_file}" "${type}" "compiler builtin")
set(CMAKE_CXX_FLAGS "${old_CMAKE_CXX_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "${old_CMAKE_EXE_LINKER_FLAGS}")
set(${RESULT} "${result}" PARENT_SCOPE)
endfunction(check_builtin)
function(check_compiler_flag RESULT FLAG)
check_flag(result "${FLAG}" compiler)
set(${RESULT} "${result}" PARENT_SCOPE)
endfunction(check_compiler_flag)
function(check_linker_flag RESULT FLAG)
check_flag(result "${FLAG}" linker)
set(${RESULT} "${result}" PARENT_SCOPE)
endfunction(check_linker_flag)
function(add_cxxflag FLAG)
check_compiler_flag(RESULT "${FLAG}")
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${RESULT}" PARENT_SCOPE)
if(NOT DEFINED RESULT OR RESULT STREQUAL "")
set(FLAG_FOUND 0 PARENT_SCOPE)
else()
set(FLAG_FOUND 1 PARENT_SCOPE)
endif()
endfunction(add_cxxflag)
function(add_ldflag FLAG)
check_linker_flag(RESULT "${FLAG}")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${RESULT}" PARENT_SCOPE)
set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${RESULT}" PARENT_SCOPE)
set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} ${RESULT}" PARENT_SCOPE)
if(NOT DEFINED RESULT OR RESULT STREQUAL "")
set(FLAG_FOUND 0 PARENT_SCOPE)
else()
set(FLAG_FOUND 1 PARENT_SCOPE)
endif()
endfunction(add_ldflag)
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