I'm experimentally rebuilding rawhide with the not-yet-released GCC 15 to see if anything breaks, and to help write the porting guide.  See https://fedoraproject.org/wiki/User:Dmalcolm/gcc-15

My test build with GCC 15 failed:
https://copr.fedorainfracloud.org/coprs/dmalcolm/gcc-15-smoketest-3.failed/build/8476055/

whereas my test build with GCC 14 succeeded:
https://copr.fedorainfracloud.org/coprs/dmalcolm/gcc-15-smoketest-3.failed.checker/build/8477614/

Looking at the failure logs e.g.
https://download.copr.fedorainfracloud.org/results/dmalcolm/gcc-15-smoketest-3.failed/fedora-rawhide-x86_64/08476055-a2ps/builder-live.log.gz
I see:

parseppd.y:157:1: error: conflicting types for 'yyprint'; have 'void(FILE *, int,  YYSTYPE)'
  157 | yyprint (FILE *file, int type, YYSTYPE value)
      | ^~~~~~~
parseppd.y:53:13: note: previous declaration of 'yyprint' with type 'void(void)'
   53 | static void yyprint ();
      |             ^~~~~~~

This is probably due to GCC 15 now defaulting to -std=gnu23, whereas GCC 14 defaulted to -std=gnu17, and C23 is stricter about function prototypes than C17.  It's probably fixable by fixing the function prototype (or by manually adding -std=gnu17 to the C build flags)


Reproducible: Always