mingw: Stop using .weak symbols aliases #1250
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Weak symbols on mingw-w64 target with GCC and the GNU linker is a bit broken for the intended use. When using the .weak + .set combo and the referenced symbol is undefined, LD does not produce an error but instead treat the referenced symbol like a weak symbol. This can happen if some of the link library flags is missing. The output executables will crash on run time, which can be very confusing. This change makes the WINRT_IMPL_... Windows API declarations on GNUC use asm labels instead. This means we lose the ability to "hook" these functions when compiling for mingw-w64 target. But as mentioned in [microsoft#475], developers should not be doing this anyway. [microsoft#475]: microsoft#475
kennykerr
reviewed
Dec 20, 2022
| WINRT_IMPL_LINK(WaitForSingleObject, 8) | ||
| extern "C" | ||
| { | ||
| void* __stdcall WINRT_IMPL_LoadLibraryW(wchar_t const* name) noexcept WINRT_IMPL_LINK(LoadLibraryW, 4); |
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I'm a little surprised this compiles, sticking the pragma before the semicolon in the function declaration on MSVC...
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It looks like it works in the same way as a #pragma directive on its own line, which you can also put anywhere.
kennykerr
approved these changes
Dec 20, 2022
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Weak symbols on mingw-w64 target with GCC and the GNU linker is a bit broken for the intended use. When using the .weak + .set combo and the referenced symbol is undefined, LD does not produce an error but instead treat the referenced symbol like a weak symbol. This can happen if some of the link library flags is missing. The output executables will crash on run time, which can be very confusing.
This change makes the WINRT_IMPL_... Windows API declarations on GNUC use asm labels instead. This means we lose the ability to "hook" these functions when compiling for mingw-w64 target. But as mentioned in #475, developers should not be doing this anyway.