Bug#1109071: libgcrypt20 FTBFS with gcc-15

[Helmut Grohne]

Source: libgcrypt20
Version: 1.11.0-7
Severity: important
Tags: ftbfs forky sid
User: helmutg at debian.org
Usertags: rebootstrap

Hi,

libgcrypt20 fails to build from source with gcc-15 for some 
architectures. The cause may be found in mpi/longlong.h. In several 
lines such as 193, 499 and 1409, there are function prototypes without 
arguments. This trips up the updated language standard by gcc-15 and 
building libcrypt20 now complains about excess arguments. For example:

| In file included from ../../mpi/mpih-div.c:32:
| ../../mpi/mpih-div.c: In function ‘_gcry_mpih_mod_1’:
| ../../mpi/longlong.h:190:11: error: too many arguments to function ‘__udiv_qrnnd’; expected 0, have 4
|   190 |     (q) = __udiv_qrnnd (&__r, (n1), (n0), (d));                         \
|       |           ^~~~~~~~~~~~  ~~~~
| ../../mpi/mpih-div.c:84:17: note: in expansion of macro ‘udiv_qrnnd’
|    84 |                 udiv_qrnnd(divisor_limb_inverted, dummy,
|       |                 ^~~~~~~~~~
| ../../mpi/longlong.h:193:16: note: declared here

This does not seem to affect amd64 as Matthias would have otherwise 
reported this problem already. It does affect at least alpha.

Remember that this problem does not affect trixie and that it can be 
worked around by exporting DEB_CFLAGS_APPEND=-std=gnu17. Hence, I 
recommend not fixing this before trixie is released.

Helmut