gcc-13 does not work when setting -std=c99

[ricardo-fonseca]

Output of brew config

HOMEBREW_VERSION: 4.2.15
ORIGIN: https://github.com/Homebrew/brew
HEAD: 92a4311868322188478d7a90511ec0e8e6b0d7df
Last commit: 15 hours ago
Core tap JSON: 25 Mar 09:30 UTC
Core cask tap JSON: 25 Mar 09:30 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.V9FfUb5oAs/org.xquartz:0
HOMEBREW_MAKE_JOBS: 16
Homebrew Ruby: 3.1.4 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/3.1.4/bin/ruby
CPU: 16-core 64-bit kabylake
Clang: 15.0.0 build 1500
Git: 2.39.3 => /Applications/Xcode.app/Contents/Developer/usr/bin/git
Curl: 8.4.0 => /usr/bin/curl
macOS: 14.4-x86_64
CLT: 15.3.0.0.1.1708646388
Xcode: 15.3

Output of brew doctor

Your system is ready to brew.

Description of issue

When using gcc-13 to compile a simple C program with -std=c99 the compilation fails:

$ gcc-13 -std=c99 testint64.c
In file included from /Library/Developer/CommandLineTools/SDKs/MacOSX14.sdk/usr/include/sys/_types.h:32,
                 from /usr/local/Cellar/gcc/13.2.0/lib/gcc/current/gcc/x86_64-apple-darwin23/13/include-fixed/stdint.h:61,
                 from /usr/local/Cellar/gcc/13.2.0/lib/gcc/current/gcc/x86_64-apple-darwin23/13/include/stdint.h:9,
                 from testint64.c:1:
/Library/Developer/CommandLineTools/SDKs/MacOSX14.sdk/usr/include/sys/cdefs.h:554:30: error: missing ')' after "__has_attribute"
  554 | #if __has_cpp_attribute(clang::unsafe_buffer_usage)
      |                              ^
/Library/Developer/CommandLineTools/SDKs/MacOSX14.sdk/usr/include/sys/cdefs.h:554:31: error:  ':' without preceding '?'
  554 | #if __has_cpp_attribute(clang::unsafe_buffer_usage)
      |                               ^

Compiling the program without -std=c99 works fine. This is the test program:

#include <stdint.h>
#include <stdio.h>

int main()
{
    int64_t a = -2147483649;
    printf("a = %lld\n", a );
}
``

[gromgit]

Doesn't that basically say that Apple's own Sonoma SDK is (no longer?) C99-clean?

Not sure what Homebrew maintainers can do about that.

[ricardo-fonseca]

Well, while I do not disagree with you, I was hoping for some kind of workaround on the brew side. The problem seems to be specific to the __has_cpp_attribute macro, and if I define it before compilation, e.g.,

#define __has_cpp_attribute(x) 0

I can get the code to compile with the -std=c99 flag on.

[Bo98]

This is a GCC bug being tracked upstream: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114007. It'll be fixed in GCC 13.3.

[ricardo-fonseca]

Thanks!