On Fri, 12 Sep 2025, Christian Franke via Cygwin wrote:
> First of all: thanks for providing recent clang packages!
>
> Testcase:
>
> $ cat winapi.c
> #include <windows.h>
> int WINAPI SomeDllFunction(int, int, int, int, int);
>
> int call_it()
> {
> return SomeDllFunction(1, 2, 3, 4, 5);
> }
>
> $ clang -S winapi.c # with 20.1.8 and 21.1.1
> winapi.c:2:5: warning: '__stdcall__' calling convention is not supported
> for this target
> [-Wignored-attributes]
> 2 | int WINAPI SomeDllFunction(int, int, int, int, int);
> | ^
> /usr/include/w32api/minwindef.h:98:16: note: expanded from macro 'WINAPI'
> 98 | #define WINAPI __stdcall
> | ^
> <built-in>:400:34: note: expanded from macro '__stdcall'
> 400 | #define __stdcall __attribute__((__stdcall__))
> | ^
> 1 warning generated.
>
I was wondering about this one when trying to figure out what Windows
behaviors should be enabled for Cygwin. It is a fact that x86_64 doesn't
support stdcall/thiscall/fastcall, but for Windows targets those calling
conventions are silently ignored rather than warned about.
Another thing that's got me confused in that vicinity is sysv_abi vs
ms_abi calling convention attribute. I think Cygwin defaults to ms_abi
so should allow __attribute__((sysv_abi)) to override, but I think it
would warn about that.
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