Re: [PATCH] stddef.h: add support for musl typedef macro guards

[Jeff Law <jeffreyalaw@gmail.com>]

On 11/26/2021 9:57 AM, soeren--- via Gcc-patches wrote:
> From: Sören Tempel <soeren+git@soeren-tempel.net>
>
> The stddef.h header checks/sets various hardcoded toolchain/os specific
> macro guards to prevent redefining types such as ptrdiff_t, wchar_t, or
> size_t. However, without this patch, the file does not check/set the
> typedef macro guards for musl libc. This causes types such as size_t to
> be defined twice for files which include both musl's stddef.h as well as
> GCC's ginclude/stddef.h. This is, for example, the case for
> libgo/sysinfo.c. If libgo/sysinfo.c has multiple typedefs for size_t
> this confuses -fdump-go-spec and causes size_t not to be included in the
> generated type definitions thereby causing a gcc-go compilation failure
> on Alpine Linux Edge (which uses musl libc) with the following error:
>
> 	sysinfo.go:7765:13: error: use of undefined type '_size_t'
> 	 7765 | type Size_t _size_t
> 	      |             ^
> 	libcall_posix.go:49:35: error: non-integer len argument in make
> 	   49 |                 b := make([]byte, len)
> 	      |
>
> This commit fixes this issue by ensuring that ptrdiff_t, wchar_t, and size_t
> are only defined once in the pre-processed libgo/sysinfo.c file by enhancing
> gcc/ginclude/stddef.h with musl-specific typedef macro guards.
>
> gcc/ChangeLog:
>
> 	* ginclude/stddef.h (__DEFINED_ptrdiff_t): Add support for musl
> 	libc typedef macro guard.
> 	(__DEFINED_size_t): Ditto.
> 	(__DEFINED_wchar_t): Ditto.
So what doesn't make sense here is how both stddef.h files get 
included.  That's the core problem I think you need to resolve.

Jeff