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build: Better detect (and permit disabling) std::filesystem in CMake.
This should transparently identify when it's available in standard or experimental forms, as well as when it requires stdc++fs to be linked.
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5 files changed

+110
-8
lines changed

5 files changed

+110
-8
lines changed

‎changes/sdk/pr.192.gh.OpenXR-SDK-Source.md‎

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@@ -0,0 +1,4 @@
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---
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- pr.188.gh.OpenXR-SDK-Source
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---
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Allow disabling of std::filesystem usage, and detect if it's available and what its requirements are.

‎src/CMakeLists.txt‎

Lines changed: 9 additions & 1 deletion
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@@ -17,12 +17,17 @@
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# Author:
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#
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if(POLICY CMP0075)
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cmake_policy(SET CMP0075 NEW)
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endif()
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# Entire project uses C++14
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set(CMAKE_CXX_STANDARD 14)
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set(CMAKE_POSITION_INDEPENDENT_CODE ON)
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set(CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
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include(GNUInstallDirs)
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include(StdFilesystemFlags)
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### Dependencies
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set(OpenGL_GL_PREFERENCE GLVND)
@@ -61,6 +66,7 @@ option(
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"Enable exception handling in the loader. Leave this on unless your standard library is built to not throw."
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ON
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)
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if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
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option(DYNAMIC_LOADER "Build the loader as a .dll library" OFF)
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else()
@@ -80,6 +86,8 @@ include(CMakeDependentOption)
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cmake_dependent_option(
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BUILD_WITH_SYSTEM_JSONCPP "Use system jsoncpp instead of vendored source" ON "JSONCPP_FOUND" OFF
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)
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cmake_dependent_option(BUILD_WITH_STD_FILESYSTEM "Use std::[experimental::]filesystem." ON
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"HAVE_FILESYSTEM_WITHOUT_LIB OR HAVE_FILESYSTEM_NEEDING_LIB" OFF)
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# Several files use these compile-time OS switches
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if(WIN32)
@@ -90,7 +98,7 @@ endif()
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# /EHsc (support for C++ exceptions) is default in most configurations but seems missing when building arm/arm64.
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if(MSVC)
93-
set(CMAKE_CXX_FLAGS "/EHsc ${CMAKE_CXX_FLAGS}")
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set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /EHsc")
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endif()
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# This is a little helper library for setting up OpenGL

‎src/cmake/StdFilesystemFlags.cmake‎

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# Copyright 2020, Collabora, Ltd.
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#
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# SPDX-License-Identifier: BSL-1.0
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include(CheckCXXSourceCompiles)
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set(_stdfs_test_source
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"bool is_reg_file(const std::string &path) { return fs::is_regular_file(path); }
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int main() {
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(void)is_reg_file(\"/etc/os-release\");
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return 0;
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}
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"
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)
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set(_stdfs_source
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"#if __cplusplus >= 201703L
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#include <filesystem>
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namespace fs = std::filesystem;
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#endif
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${_stdfs_test_source}
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"
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)
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set(_stdfs_experimental_source
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"#if __cplusplus < 201703L
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#include <experimental/filesystem>
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namespace fs = std::experimental::filesystem;
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#endif
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${_stdfs_test_source}
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"
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)
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set(_stdfs_needlib_source
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"#if __cplusplus >= 201703L
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#include <filesystem>
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namespace fs = std::filesystem;
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#else
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#include <experimental/filesystem>
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namespace fs = std::experimental::filesystem;
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#endif
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${_stdfs_test_source}
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"
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)
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# First, just look for the include.
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set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
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set(CMAKE_REQUIRED_LIBRARIES)
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check_cxx_source_compiles("${_stdfs_source}" HAVE_FILESYSTEM_IN_STD)
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check_cxx_source_compiles("${_stdfs_experimental_source}" HAVE_FILESYSTEM_IN_STDEXPERIMENTAL)
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set(CMAKE_REQUIRED_FLAGS "-DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=TRUE")
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check_cxx_source_compiles("${_stdfs_source}" HAVE_FILESYSTEM_IN_STD_17)
50+
unset(CMAKE_REQUIRED_FLAGS)
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52+
if(HAVE_FILESYSTEM_IN_STD_17 AND NOT HAVE_FILESYSTEM_IN_STD)
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set(HAVE_FILESYSTEM_NEEDS_17
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ON
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CACHE INTERNAL ""
56+
)
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set(CMAKE_REQUIRED_FLAGS "-DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_STANDARD_REQUIRED=TRUE")
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else()
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set(HAVE_FILESYSTEM_NEEDS_17
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OFF
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CACHE INTERNAL ""
62+
)
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endif()
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# Now, see if we need
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set(CMAKE_TRY_COMPILE_TARGET_TYPE EXECUTABLE)
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check_cxx_source_compiles("${_stdfs_needlib_source}" HAVE_FILESYSTEM_WITHOUT_LIB)
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set(CMAKE_REQUIRED_LIBRARIES stdc++fs)
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check_cxx_source_compiles("${_stdfs_needlib_source}" HAVE_FILESYSTEM_NEEDING_LIB)
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71+
function(openxr_add_filesystem_utils TARGET_NAME)
72+
target_sources(${TARGET_NAME} PRIVATE ${PROJECT_SOURCE_DIR}/src/common/filesystem_utils.cpp)
73+
target_include_directories(${TARGET_NAME} PRIVATE ${PROJECT_SOURCE_DIR}/src/common)
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if(NOT BUILD_WITH_STD_FILESYSTEM)
75+
target_compile_definitions(${TARGET_NAME} PRIVATE DISABLE_STD_FILESYSTEM)
76+
else()
77+
if(HAVE_FILESYSTEM_NEEDS_17)
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set_property(TARGET ${TARGET_NAME} PROPERTY CXX_STANDARD 17)
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set_property(TARGET ${TARGET_NAME} PROPERTY CXX_STANDARD_REQUIRED TRUE)
80+
endif()
81+
if(HAVE_FILESYSTEM_NEEDING_LIB AND NOT HAVE_FILESYSTEM_WITHOUT_LIB)
82+
target_link_libraries(${TARGET_NAME} PRIVATE stdc++fs)
83+
endif()
84+
endif()
85+
endfunction()

‎src/loader/CMakeLists.txt‎

Lines changed: 1 addition & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -59,8 +59,6 @@ add_library(openxr_loader ${LIBRARY_TYPE}
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runtime_interface.cpp
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runtime_interface.hpp
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${GENERATED_OUTPUT}
62-
${PROJECT_SOURCE_DIR}/src/common/filesystem_utils.cpp
63-
${PROJECT_SOURCE_DIR}/src/common/filesystem_utils.hpp
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${PROJECT_SOURCE_DIR}/src/common/hex_and_handles.h
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${PROJECT_SOURCE_DIR}/src/common/object_info.cpp
6664
${PROJECT_SOURCE_DIR}/src/common/object_info.h
@@ -117,6 +115,7 @@ target_link_libraries(
117115
)
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119117
target_compile_definitions(openxr_loader PRIVATE API_NAME="OpenXR")
118+
openxr_add_filesystem_utils(openxr_loader)
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121120
if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
122121
set(FALLBACK_CONFIG_DIRS
@@ -145,7 +144,6 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
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set_target_properties(openxr_loader PROPERTIES SOVERSION "${MAJOR}" VERSION "${MAJOR}.${MINOR}.${PATCH}")
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target_link_libraries(
147146
openxr_loader
148-
PRIVATE stdc++fs
149147
PUBLIC m
150148
)
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‎src/tests/loader_test/CMakeLists.txt‎

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -20,13 +20,14 @@
2020
add_executable(loader_test
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loader_test_utils.cpp
2222
loader_test.cpp
23-
${PROJECT_SOURCE_DIR}/src/common/filesystem_utils.cpp
2423
)
24+
openxr_add_filesystem_utils(loader_test)
2525
set_target_properties(loader_test PROPERTIES FOLDER ${TESTS_FOLDER})
26+
target_link_libraries(loader_test PRIVATE openxr_loader ${CMAKE_THREAD_LIBS_INIT})
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2728
add_dependencies(loader_test generate_openxr_header)
2829
if(TARGET openxr-gfxwrapper)
29-
target_link_libraries(loader_test openxr-gfxwrapper)
30+
target_link_libraries(loader_test PRIVATE openxr-gfxwrapper)
3031
endif()
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target_include_directories(
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loader_test
@@ -47,13 +48,19 @@ if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
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target_compile_definitions(loader_test PRIVATE _CRT_SECURE_NO_WARNINGS)
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target_compile_options(loader_test PRIVATE /Zc:wchar_t /Zc:forScope /W4 /WX)
4950
endif()
50-
target_link_libraries(loader_test openxr_loader opengl32 d3d11)
51+
if(OPENGL_FOUND)
52+
target_link_libraries(loader_test opengl32)
53+
endif()
54+
if(D3D_D3D11_FOUND)
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target_link_libraries(loader_test d3d11)
56+
endif()
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5158
elseif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
5259
target_compile_options(
5360
loader_test PRIVATE -Wall -Wno-unused-function -Wno-format-truncation
5461
)
5562

56-
target_link_libraries(loader_test -lstdc++fs openxr_loader m -lpthread)
63+
target_link_libraries(loader_test PRIVATE m)
5764
else()
5865
message(FATAL_ERROR "Unsupported Platform")
5966
endif()

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