Bug#1096673: gap-float: ftbfs with GCC-15

[Matthias Klose]

Package: src:gap-float
Version: 1.0.5+ds-1
Severity: important
Tags: sid forky
User: debian-gcc at 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/gap-float_1.0.5+ds-1_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

[...]
mpc.c:751:16: error: initialization of 'struct OpaqueBag * (*)(void)' from incompatible pointer type 'struct OpaqueBag * (*)(struct OpaqueBag *, struct OpaqueBag *, struct OpaqueBag *)' [-Wincompatible-pointer-types]
  751 |   Inc2_MPC_arg(MPC_INTPREC,"int, int"),
      |                ^~~~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:751:16: note: (near initialization for 'GVarFuncs[67].handler')
  751 |   Inc2_MPC_arg(MPC_INTPREC,"int, int"),
      |                ^~~~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:347:12: note: 'MPC_INTPREC' declared here
  347 | static Obj MPC_INTPREC(Obj self, Obj i, Obj prec)
      |            ^~~~~~~~~~~
mpc.c:752:16: error: initialization of 'struct OpaqueBag * (*)(void)' from incompatible pointer type 'struct OpaqueBag * (*)(struct OpaqueBag *, struct OpaqueBag *, struct OpaqueBag *)' [-Wincompatible-pointer-types]
  752 |   Inc2_MPC_arg(MPC_MPCPREC,"complex, int"),
      |                ^~~~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:752:16: note: (near initialization for 'GVarFuncs[68].handler')
  752 |   Inc2_MPC_arg(MPC_MPCPREC,"complex, int"),
      |                ^~~~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:368:12: note: 'MPC_MPCPREC' declared here
  368 | static Obj MPC_MPCPREC(Obj self, Obj f, Obj prec)
      |            ^~~~~~~~~~~
mpc.c:753:16: error: initialization of 'struct OpaqueBag * (*)(void)' from incompatible pointer type 'struct OpaqueBag * (*)(struct OpaqueBag *, struct OpaqueBag *, struct OpaqueBag *)' [-Wincompatible-pointer-types]
  753 |   Inc2_MPC_arg(MPC_2MPFR,"complex, complex"),
      |                ^~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:753:16: note: (near initialization for 'GVarFuncs[69].handler')
  753 |   Inc2_MPC_arg(MPC_2MPFR,"complex, complex"),
      |                ^~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:632:12: note: 'MPC_2MPFR' declared here
  632 | static Obj MPC_2MPFR (Obj self, Obj fl, Obj fr)
      |            ^~~~~~~~~
mpc.c:755:16: error: initialization of 'struct OpaqueBag * (*)(void)' from incompatible pointer type 'struct OpaqueBag * (*)(struct OpaqueBag *, struct OpaqueBag *, struct OpaqueBag *)' [-Wincompatible-pointer-types]
  755 |   Inc2_MPC_arg(ROOTPOLY_MPC,"coeffs, prec"),
      |                ^~~~~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:755:16: note: (near initialization for 'GVarFuncs[70].handler')
  755 |   Inc2_MPC_arg(ROOTPOLY_MPC,"coeffs, prec"),
      |                ^~~~~~~~~~~~
mpc.c:546:20: note: in definition of macro 'Inc2_MPC_arg'
  546 |   { #name, 2, arg, name, "src/mpc.c:" #name }
      |                    ^~~~
mpc.c:645:12: note: 'ROOTPOLY_MPC' declared here
  645 | static Obj ROOTPOLY_MPC (Obj self, Obj coeffs, Obj precision)
      |            ^~~~~~~~~~~~
make[3]: *** [Makefile:649: float_la-mpfi.lo] Error 1
make[3]: *** [Makefile:642: float_la-mpc.lo] Error 1
make[3]: Leaving directory '/build/reproducible-path/gap-float-1.0.5+ds/src'
make[2]: *** [Makefile:447: all] Error 2
make[2]: Leaving directory '/build/reproducible-path/gap-float-1.0.5+ds/src'
make[1]: *** [Makefile:498: all-recursive] Error 1
make[1]: Leaving directory '/build/reproducible-path/gap-float-1.0.5+ds'
dh_auto_build: error: make -j8 returned exit code 2
make: *** [debian/rules:16: binary] Error 25
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2