[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/vtwm_5.4.7-8_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

[...]
menus.h:180:18: note: declared here
  180 | extern MenuRoot *NewMenuRoot();
      |                  ^~~~~~~~~~~
gram.y:1131:9: error: too many arguments to function ‘GetColor’; expected 0, have 3
 1131 |         GetColor(COLOR, &tmp->highlight.fore, fore);
      |         ^~~~~~~~
In file included from twm.h:63:
util.h:58:25: note: declared here
   58 | extern void             GetColor();
      |                         ^~~~~~~~
gram.y:1132:9: error: too many arguments to function ‘GetColor’; expected 0, have 3
 1132 |         GetColor(COLOR, &tmp->highlight.back, back);
      |         ^~~~~~~~
util.h:58:25: note: declared here
   58 | extern void             GetColor();
      |                         ^~~~~~~~
gram.y: In function ‘GotButton’:
gram.y:1140:13: warning: old-style function definition [-Wold-style-definition]
 1140 | static void GotButton(butt, func)
      |             ^~~~~~~~~
gram.y:1160:20: error: too many arguments to function ‘GetRoot’; expected 0, have 3
 1160 |             root = GetRoot(TWM_ROOT, NULLSTR, NULLSTR);
      |                    ^~~~~~~
gram.y:1110:18: note: declared here
 1110 | static MenuRoot *GetRoot(name, fore, back)
      |                  ^~~~~~~
gram.y:1162:46: error: too many arguments to function ‘AddToMenu’; expected 0, have 7
 1162 |             Scr->Mouse[butt][i][mods].item = AddToMenu(root,"x",Action,
      |                                              ^~~~~~~~~ ~~~~
menus.h:182:18: note: declared here
  182 | extern MenuItem *AddToMenu();
      |                  ^~~~~~~~~
gram.y: In function ‘GotKey’:
gram.y:1174:13: warning: old-style function definition [-Wold-style-definition]
 1174 | static void GotKey(key, func)
      |             ^~~~~~
gram.y:1184:14: error: too many arguments to function ‘AddFuncKey’; expected 0, have 6
 1184 |         if (!AddFuncKey(key, i, mods, func, Name, Action))
      |              ^~~~~~~~~~ ~~~
menus.h:185:13: note: declared here
  185 | extern Bool AddFuncKey();
      |             ^~~~~~~~~~
gram.y: In function ‘GotTitleButton’:
gram.y:1196:13: warning: old-style function definition [-Wold-style-definition]
 1196 | static void GotTitleButton (bitmapname, func, rightside)
      |             ^~~~~~~~~~~~~~
gram.y:1201:10: error: too many arguments to function ‘CreateTitleButton’; expected 0, have 6
 1201 |     if (!CreateTitleButton (bitmapname, func, Action, pull, rightside, True)) {
      |          ^~~~~~~~~~~~~~~~~  ~~~~~~~~~~
menus.h:202:12: note: declared here
  202 | extern int CreateTitleButton();
      |            ^~~~~~~~~~~~~~~~~
gram.y: In function ‘CheckWarpScreenArg’:
gram.y:1211:13: warning: old-style function definition [-Wold-style-definition]
 1211 | static Bool CheckWarpScreenArg (s)
      |             ^~~~~~~~~~~~~~~~~~
gram.y: In function ‘CheckWarpRingArg’:
gram.y:1226:13: warning: old-style function definition [-Wold-style-definition]
 1226 | static Bool CheckWarpRingArg (s)
      |             ^~~~~~~~~~~~~~~~
gram.y: In function ‘CheckColormapArg’:
gram.y:1239:13: warning: old-style function definition [-Wold-style-definition]
 1239 | static Bool CheckColormapArg (s)
      |             ^~~~~~~~~~~~~~~~
make[2]: *** [<builtin>: gram.o] Error 1
make[2]: Leaving directory '/build/reproducible-path/vtwm-5.4.7'
make[1]: *** [debian/rules:30: override_dh_auto_build] Error 2
make[1]: Leaving directory '/build/reproducible-path/vtwm-5.4.7'
make: *** [debian/rules:24: binary] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2