ceph/cmake/modules/FindStdFilesystem.cmake
Kefu Chai 6cf7ebd0ca cmake: do not always require extra link flags for std::filesystem
since GCC-9

> Using the types and functions in <filesystem> does not require linking
> with -lstdc++fs now.

see https://gcc.gnu.org/gcc-9/changes.html#libstdcxx

Signed-off-by: Kefu Chai <kchai@redhat.com>
2020-12-02 19:42:34 +08:00

58 lines
1.7 KiB
CMake

set(_std_filesystem_test_src
${CMAKE_CURRENT_LIST_DIR}/FindStdFilesystem_test.cc)
macro(try_std_filesystem_library _library _result _already_included)
set(_std_filesystem_try_compile_arg
CXX_STANDARD 17)
if(NOT _library STREQUAL "")
list(APPEND _std_filesystem_try_compile_arg
LINK_LIBRARIES ${_library})
endif()
try_compile(_std_filesystem_compiles
${CMAKE_CURRENT_BINARY_DIR}
SOURCES ${_std_filesystem_test_src}
${_std_filesystem_try_compile_arg})
unset(_std_filesystem_try_compile_arg)
if(_std_filesystem_compiles)
if(NOT _library STREQUAL "")
set(${_result} ${_library})
else()
set(${_already_included} "included by standard library")
endif()
endif()
unset(_std_filesystem_compiles)
endmacro()
set(_std_filesystem_required_var "StdFilesystem_LIBRARY")
set(_std_filesystem_already_included FALSE)
foreach(library
""
"stdc++fs"
"c++experimental"
"c++fs")
try_std_filesystem_library("${library}" StdFilesystem_LIBRARY _std_filesystem_already_included)
if(_std_filesystem_already_included)
set(_std_filesystem_required_var "_std_filesystem_already_included")
break()
elseif(StdFilesystem_LIBRARY)
break()
endif()
endforeach()
unset(_std_filesystem_test_src)
include(FindPackageHandleStandardArgs)
find_package_handle_standard_args(StdFilesystem
FOUND_VAR StdFilesystem_FOUND
REQUIRED_VARS ${_std_filesystem_required_var})
mark_as_advanced(StdFilesystem_LIBRARY)
if(StdFilesystem_FOUND AND NOT (TARGET StdFilesystem::filesystem))
add_library(StdFilesystem::filesystem INTERFACE IMPORTED)
if(StdFilesystem_LIBRARY)
set_target_properties(StdFilesystem::filesystem PROPERTIES
INTERFACE_LINK_LIBRARIES ${StdFilesystem_LIBRARY})
endif()
endif()