Unknown type name '__va_list' errors on samples

[Cryptogenic]

A few people have tested and with VS2019 (possibly other versions?), they've reported unknown type name '__va_list' errors in the stdio.h. header.

[Cryptogenic]

Discovered the issue isn't in the toolchain itself, it's an issue in the newest LLVM / clang. On clang 7.0.1 this issue isn't present, but it is on 10.0.0.

[Tustin]

As a test, try including cstdarg. Seems to generate an eboot for me but I can't test it on PS4 to confirm.

#include <cstdarg>
#include <stdio.h>
#include <orbis/libkernel.h>

[Cryptogenic]

Root cause found, essentially Clang 10.0+ doesn't act like GCC anymore and therefore doesn't define __GNUC__, which is used by the libc headers for defining builtins. As per Clang 10.0 release notes:

The -fgnuc-version= flag now controls the value of GNUC and related macros. This flag does not enable or disable any GCC extensions implemented in Clang. Setting the version to zero causes Clang to leave GNUC and other GNU-namespaced macros, such as GXX_WEAK, undefined.

source: https://releases.llvm.org/10.0.0/tools/clang/docs/ReleaseNotes.html

The best fix we came up with was to add a check in sys/cdefs.h for clang 10.0 and higher, and forcefully define __GNUC__.

#if __clang_major__ >= 10 && !defined(__GNUC__)
#define __GNUC__ 3
#endif

Massive thanks to @idc and @frangarcj for pointing out the issue in the release notes.