Bug#1096643: flip: ftbfs with GCC-15

[Matthias Klose <doko@debian.org>]

Package: src:flip
Version: 1.20-5
Severity: important
Tags: sid forky
User: debian-gcc@lists.debian.org
Usertags: ftbfs-gcc-15

[This bug is NOT targeted to the upcoming trixie release]

Please keep this issue open in the bug tracker for the package it
was filed for.  If a fix in another package is required, please
file a bug for the other package (or clone), and add a block in this
package. Please keep the issue open until the package can be built in
a follow-up test rebuild.

The package fails to build in a test rebuild on at least amd64 with
gcc-15/g++-15, but succeeds to build with gcc-14/g++-14. The
severity of this report will be raised before the forky release.

The full build log can be found at:
http://qa-logs.debian.net/2025/02/16/amd64exp/flip_1.20-5_unstable_gccexp.log.gz
The last lines of the build log are at the end of this report.

To build with GCC 15, either set CC=gcc-15 CXX=g++-15 explicitly,
or install the gcc, g++, gfortran, ... packages from experimental.

  apt-get -t=experimental install g++ 

GCC 15 now defaults to the C23/C++23 standards, exposing many FTBFS.
Other Common build failures are new warnings resulting in build failures
with -Werror turned on, or new/dropped symbols in Debian symbols files.
For other C/C++ related build failures see the porting guide at
http://gcc.gnu.org/gcc-15/porting_to.html

[...]
/usr/include/signal.h:72:16: note: ‘__sighandler_t’ declared here
   72 | typedef void (*__sighandler_t) (int);
      |                ^~~~~~~~~~~~~~
flip.c:540:24: error: passing argument 2 of ‘signal’ from incompatible pointer type [-Wincompatible-pointer-types]
  540 |       signal (SIGTERM, cleanup);
      |                        ^~~~~~~
      |                        |
      |                        void (*)(void)
/usr/include/signal.h:88:57: note: expected ‘__sighandler_t’ {aka ‘void (*)(int)’} but argument is of type ‘void (*)(void)’
   88 | extern __sighandler_t signal (int __sig, __sighandler_t __handler)
      |                                          ~~~~~~~~~~~~~~~^~~~~~~~~
flip.c:35:6: note: ‘cleanup’ declared here
   35 | void cleanup PARMS ((int));
      |      ^~~~~~~
/usr/include/signal.h:72:16: note: ‘__sighandler_t’ declared here
   72 | typedef void (*__sighandler_t) (int);
      |                ^~~~~~~~~~~~~~
flip.c: In function ‘cleanup’:
flip.c:545:6: warning: old-style function definition [-Wold-style-definition]
  545 | void cleanup(sig)
      |      ^~~~~~~
flip.c:547:1: error: number of arguments doesn’t match prototype
  547 | {
      | ^
flip.c:35:6: error: prototype declaration
   35 | void cleanup PARMS ((int));
      |      ^~~~~~~
flip.c:550:17: error: passing argument 2 of ‘signal’ from incompatible pointer type [-Wincompatible-pointer-types]
  550 |    signal (sig, cleanup);     /* ditto */
      |                 ^~~~~~~
      |                 |
      |                 void (*)(void)
/usr/include/signal.h:88:57: note: expected ‘__sighandler_t’ {aka ‘void (*)(int)’} but argument is of type ‘void (*)(void)’
   88 | extern __sighandler_t signal (int __sig, __sighandler_t __handler)
      |                                          ~~~~~~~~~~~~~~~^~~~~~~~~
flip.c:545:6: note: ‘cleanup’ declared here
  545 | void cleanup(sig)
      |      ^~~~~~~
/usr/include/signal.h:72:16: note: ‘__sighandler_t’ declared here
   72 | typedef void (*__sighandler_t) (int);
      |                ^~~~~~~~~~~~~~
flip.c: In function ‘error’:
flip.c:557:6: warning: old-style function definition [-Wold-style-definition]
  557 | void error (msg1, msg2)
      |      ^~~~~
flip.c:559:1: error: number of arguments doesn’t match prototype
  559 | {
      | ^
flip.c:33:6: error: prototype declaration
   33 | void error PARMS ((char *, char *));
      |      ^~~~~
flip.c: In function ‘flip_exit’:
flip.c:612:6: warning: old-style function definition [-Wold-style-definition]
  612 | void flip_exit(stat)
      |      ^~~~~~~~~
flip.c:614:1: error: number of arguments doesn’t match prototype
  614 | {
      | ^
flip.c:26:6: error: prototype declaration
   26 | void flip_exit PARMS ((int));
      |      ^~~~~~~~~
flip.c: At top level:
flip.c:3:13: warning: ‘sccsid’ defined but not used [-Wunused-variable]
    3 | static char sccsid[]="::[[ @(#) flip.c 1.20 2008-07-26 ]]::";
      |             ^~~~~~
make[1]: *** [Makefile:72: flip.o] Error 1
make[1]: Leaving directory '/build/reproducible-path/flip-1.20'
dh_auto_build: error: make -j8 "INSTALL=install --strip-program=true" returned exit code 2
make: *** [debian/rules:23: binary] Error 25
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2