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/8476056/

whereas my test build with GCC 14 succeeded:
https://copr.fedorainfracloud.org/coprs/dmalcolm/gcc-15-smoketest-3.failed.checker/build/8477612/

Looking at the failure logs e.g.
https://download.copr.fedorainfracloud.org/results/dmalcolm/gcc-15-smoketest-3.failed/fedora-rawhide-x86_64/08476056-a52dec/builder-live.log.gz
I see:

a52dec.c: In function ‘print_fps’:
a52dec.c:82:25: error: passing argument 2 of ‘signal’ from incompatible pointer type [-Wincompatible-pointer-types]
   82 |         signal (SIGINT, signal_handler);
      |                         ^~~~~~~~~~~~~~
      |                         |
      |                         int (*)(int)
In file included from a52dec.c:32:
/usr/include/signal.h:88:57: note: expected ‘__sighandler_t’ {aka ‘void (*)(int)’} but argument is of type ‘int (*)(int)’
   88 | extern __sighandler_t signal (int __sig, __sighandler_t __handler)
      |                                          ~~~~~~~~~~~~~~~^~~~~~~~~

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 prototypes (or by manually adding -std=gnu17 to the C build flags)


Reproducible: Always