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MinGW: `CATCH_CONFIG_MAIN` defines the non-standard `WinMain` instead of the standard `main` function
Describe the bug
Once you define the CATCH_CONFIG_MAIN definition on MinGW, it defines a non-standard main function called WinMain. This results in a lot of undefined references. This doesn't happen with other compilers.
https://github.com/aminya/cpp_vcpkg_project/runs/6542106054?check_suite_focus=true#step:6:203
[6/18] Linking CXX executable my_exe\test\Debug\my_exe_helpers_tests.exe
FAILED: my_exe/test/Debug/my_exe_helpers_tests.exe
cmd.exe /C "cd . && C:\Users\runneradmin\gcc\mingw64\bin\g++.exe -g my_exe/test/CMakeFiles/my_exe_helpers_tests.dir/Debug/tests.cpp.obj -o my_exe\test\Debug\my_exe_helpers_tests.exe -Wl,--out-implib,my_exe\test\Debug\libmy_exe_helpers_tests.dll.a -Wl,--major-image-version,0,--minor-image-version,0 vcpkg_installed/x64-mingw-static/debug/lib/libfmtd.a --coverage -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 && cd ."
c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-crt0_c.o):crt0_c.c:(.text+0x46): undefined reference to `WinMain'
collect2.exe: error: ld returned 1 exit status
[7/18] Linking CXX executable my_lib\test\Debug\my_lib_tests.exe
FAILED: my_lib/test/Debug/my_lib_tests.exe my_lib/test/my_lib_tests_tests-84286ba.cmake D:/a/cpp_vcpkg_project/cpp_vcpkg_project/build/my_lib/test/my_lib_tests_tests-84286ba.cmake
cmd.exe /C "cd . && C:\Users\runneradmin\gcc\mingw64\bin\g++.exe -g my_lib/test/CMakeFiles/my_lib_tests.dir/Debug/tests.cpp.obj -o my_lib\test\Debug\my_lib_tests.exe -Wl,--out-implib,my_lib\test\Debug\libmy_lib_tests.dll.a -Wl,--major-image-version,0,--minor-image-version,0 my_lib/Debug/libmy_lib.a --coverage vcpkg_installed/x64-mingw-static/debug/lib/libfmtd.a -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 && cmd.exe /C "cd /D D:\a\cpp_vcpkg_project\cpp_vcpkg_project\build\my_lib\test && C:\Users\runneradmin\cmake\cmake-3.23.1-windows-x86_64\bin\cmake.exe -D TEST_TARGET=my_lib_tests -D TEST_EXECUTABLE=D:/a/cpp_vcpkg_project/cpp_vcpkg_project/build/my_lib/test/Debug/my_lib_tests.exe -D TEST_EXECUTOR= -D TEST_WORKING_DIR=D:/a/cpp_vcpkg_project/cpp_vcpkg_project/build/my_lib/test -D TEST_SPEC= -D TEST_EXTRA_ARGS= -D TEST_PROPERTIES= -D TEST_PREFIX= -D TEST_SUFFIX= -D TEST_LIST=my_lib_tests_TESTS -D TEST_REPORTER=xml -D TEST_OUTPUT_DIR= -D TEST_OUTPUT_PREFIX= -D TEST_OUTPUT_SUFFIX= -D CTEST_FILE=D:/a/cpp_vcpkg_project/cpp_vcpkg_project/build/my_lib/test/my_lib_tests_tests-84286ba.cmake -P D:/a/cpp_vcpkg_project/cpp_vcpkg_project/build/vcpkg_installed/x64-mingw-static/share/catch2/CatchAddTests.cmake""
c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-crt0_c.o):crt0_c.c:(.text+0x46): undefined reference to `WinMain'
collect2.exe: error: ld returned 1 exit status
[8/18] Building CXX object my_header_lib/test/constexpr/CMakeFiles/my_header_lib_relaxed_constexpr_tests.dir/Debug/constexpr_tests.cpp.obj
Checking D:\a\cpp_vcpkg_project\cpp_vcpkg_project\my_header_lib\test\constexpr\constexpr_tests.cpp ...
Checking D:\a\cpp_vcpkg_project\cpp_vcpkg_project\my_header_lib\test\constexpr\constexpr_tests.cpp: CATCH_CONFIG_MAIN=1;CATCH_CONFIG_RUNTIME_STATIC_REQUIRE=1;FMT_LOCALE=1;UNICODE=1;_UNICODE=1;CMAKE_INTDIR="Debug"...
ninja: build stopped: subcommand failed.
task: Failed to run task "coverage": task: Failed to run task "build_template": exit status 1
Expected behavior
CATCH_CONFIG_MAIN should define a standard main on MinGW
Reproduction steps
- Install MinGW from here
- Clone this branch: https://github.com/aminya/cpp_vcpkg_project/tree/mingw
- Then run
task testormake test
Platform information:
- OS: Windows NT
- Compiler+version: GCC v11
- Catch version: v2.13.7
Additional context
Blocks https://github.com/aminya/project_options/issues/129 Related issues:
- https://github.com/brechtsanders/winlibs_mingw/issues/106
- https://sourceforge.net/p/mingw-w64/bugs/942/
- https://github.com/catchorg/Catch2/issues/1287
There is an explicit code that results in this issue. I don't know why just Catch2 doesn't use main on Windows similar to others!
https://github.com/catchorg/Catch2/blob/e33de8fc05ca80923a8216a8aecd6a1afc5e00af/include/internal/catch_default_main.hpp#L16-L18
I am pretty sure you are wrong here.
This linking error:
c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-crt0_c.o):crt0_c.c:(.text+0x46): undefined reference to `WinMain'
means that libmingw32.a is missing the reference to WinMain (because Catch2 doesn't provide it, it isn't a GUI subsystem application).
From a quick google, the issue is that you need to add -municode when building the executable (likely the link step is enough) so that MinGW understands to target wmain entry point and not main entry point.
Adding -municode doesn't fix undefined references to `WinMain' https://github.com/aminya/project_options/issues/129
Why do you want to use non-standard wmain on Windows?
-municode needs to be added as link option, not compile option.
As to your question, wmain is used on Windows, when you provide _UNICODE define during compilation. This means that you require support for unicode, which requires wmain so that you can accept wchar_t (unicode-ish) arguments.
If you want to keep this Unicode default on MinGW, you should handle -municode inside Catch2's CMake files. By default, it is not possible to build a simple test on MinGW.
Adding -municode to the link options changes the error: undefined reference to 'wWinMain'
https://github.com/aminya/project_options/runs/6819912259?check_suite_focus=true#step:5:458
cmd.exe /C "cd . && C:\Users\runneradmin\gcc\mingw64\bin\g++.exe -O3 -DNDEBUG -municode CMakeFiles/main.dir/Release/src/main/main.cpp.obj -o Release\main.exe -Wl,--out-implib,Release\libmain.dll.a -Wl,--major-image-version,0,--minor-image-version,0 vcpkg_installed/x64-mingw-static/lib/libfmt.a --coverage -lkernel32 -luser32 -lgdi32 -lwinspool -lshell32 -lole32 -loleaut32 -luuid -lcomdlg32 -ladvapi32 && cmd.exe /C "cd /D D:\a\project_options\project_options\test\build && "C:\Program Files\PowerShell\7\pwsh.exe" -noprofile -executionpolicy Bypass -file C:/Users/runneradmin/vcpkg/scripts/buildsystems/msbuild/applocal.ps1 -targetBinary D:/a/project_options/project_options/test/build/Release/main.exe -installedDir D:/a/project_options/project_options/test/build/vcpkg_installed/x64-mingw-static/bin -OutVariable out""
c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/bin/ld.exe: c:/users/runneradmin/gcc/mingw64/bin/../lib/gcc/x86_64-w64-mingw32/11.3.0/../../../../x86_64-w64-mingw32/lib/../lib/libmingw32.a(lib64_libmingw32_a-crt0_w.o):crt0_w.c:(.text+0x41): undefined reference to `wWinMain'
Mingw doesn't use wmain as wWinMain. It might be because the function prototype looks different than what Catch2 is using.
https://sourceforge.net/p/mingw-w64/wiki2/Unicode%20apps/#unicode-applications
Current MinGW status:
- Doesn't compile without Unicode because of an undefined reference to WinMain.
- Doesn't compile with Unicode because of an undefined reference to wWinMain.
This can be simply fixed by using the standard main function!
My build worked using v.3.1.0 but gives undefined reference to WinMain at v.3.2.0. Turns out in cmake I needed to link with Catch2::Catch2WithMain instead of Catch2::Catch2
For anyone who is still struggling with this, as a last resort you can provide your own main as per the example: https://github.com/catchorg/Catch2/blob/devel/docs/own-main.md
