Bug#1096610: fastforward: ftbfs with GCC-15

[Matthias Klose <doko@debian.org>]

Package: src:fastforward
Version: 1:0.51-10
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/fastforward_0.51-10_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

[...]
   38 | int substdio_bput(s,buf,len)
      |     ^~~~~~~~~~~~~
substdo.c: In function ‘substdio_puts’:
substdo.c:96:5: warning: old-style function definition [-Wold-style-definition]
   96 | int substdio_puts(s,buf)
      |     ^~~~~~~~~~~~~
substdo.c:99:1: error: number of arguments doesn’t match prototype
   99 | {
      | ^
substdio.h:24:12: error: prototype declaration
   24 | extern int substdio_puts();
      |            ^~~~~~~~~~~~~
substdo.c:100:29: error: too many arguments to function ‘str_len’; expected 0, have 1
  100 |   return substdio_put(s,buf,str_len(buf));
      |                             ^~~~~~~ ~~~
str.h:7:21: note: declared here
    7 | extern unsigned int str_len();
      |                     ^~~~~~~
substdo.c:100:10: error: too many arguments to function ‘substdio_put’; expected 0, have 3
  100 |   return substdio_put(s,buf,str_len(buf));
      |          ^~~~~~~~~~~~ ~
substdo.c:55:5: note: declared here
   55 | int substdio_put(s,buf,len)
      |     ^~~~~~~~~~~~
substdo.c: In function ‘substdio_putsflush’:
substdo.c:103:5: warning: old-style function definition [-Wold-style-definition]
  103 | int substdio_putsflush(s,buf)
      |     ^~~~~~~~~~~~~~~~~~
substdo.c:106:1: error: number of arguments doesn’t match prototype
  106 | {
      | ^
substdio.h:26:12: error: prototype declaration
   26 | extern int substdio_putsflush();
      |            ^~~~~~~~~~~~~~~~~~
substdo.c:107:34: error: too many arguments to function ‘str_len’; expected 0, have 1
  107 |   return substdio_putflush(s,buf,str_len(buf));
      |                                  ^~~~~~~ ~~~
str.h:7:21: note: declared here
    7 | extern unsigned int str_len();
      |                     ^~~~~~~
substdo.c:107:10: error: too many arguments to function ‘substdio_putflush’; expected 0, have 3
  107 |   return substdio_putflush(s,buf,str_len(buf));
      |          ^~~~~~~~~~~~~~~~~ ~
substdo.c:80:5: note: declared here
   80 | int substdio_putflush(s,buf,len)
      |     ^~~~~~~~~~~~~~~~~
slurpclose.c: In function ‘slurpclose’:
slurpclose.c:6:5: warning: old-style function definition [-Wold-style-definition]
    6 | int slurpclose(fd,sa,bufsize)
      |     ^~~~~~~~~~
slurpclose.c:10:1: error: number of arguments doesn’t match prototype
   10 | {
      | ^
In file included from slurpclose.c:3:
slurpclose.h:4:12: error: prototype declaration
    4 | extern int slurpclose();
      |            ^~~~~~~~~~
slurpclose.c:13:10: error: too many arguments to function ‘stralloc_readyplus’; expected 0, have 2
   13 |     if (!stralloc_readyplus(sa,bufsize)) { close(fd); return -1; }
      |          ^~~~~~~~~~~~~~~~~~ ~~
In file included from slurpclose.c:1:
stralloc.h:9:12: note: declared here
    9 | extern int stralloc_readyplus();
      |            ^~~~~~~~~~~~~~~~~~
make[1]: *** [Makefile:569: substdo.o] Error 1
make[1]: *** [Makefile:437: slurpclose.o] Error 1
make[1]: Leaving directory '/build/reproducible-path/fastforward-0.51'
dh_auto_build: error: make -j8 "INSTALL=install --strip-program=true" returned exit code 2
make: *** [debian/rules:9: binary] Error 25
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2