Bug#1097790: rgbpaint: ftbfs with GCC-15

[Matthias Klose]

Package: src:rgbpaint
Version: 0.8.7-7
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/rgbpaint_0.8.7-7_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

[...]
      |                        ~~~~~~~~~~~^~~~~~
viewer.c: In function ‘pan_motion’:
viewer.c:238:29: warning: unused parameter ‘widget’ [-Wunused-parameter]
  238 | gint pan_motion( GtkWidget *widget, GdkEventMotion *event )
      |                  ~~~~~~~~~~~^~~~~~
viewer.c: In function ‘pressed_pan’:
viewer.c:275:32: warning: unused parameter ‘menu_item’ [-Wunused-parameter]
  275 | void pressed_pan( GtkMenuItem *menu_item, gpointer user_data )
      |                   ~~~~~~~~~~~~~^~~~~~~~~
viewer.c:275:52: warning: unused parameter ‘user_data’ [-Wunused-parameter]
  275 | void pressed_pan( GtkMenuItem *menu_item, gpointer user_data )
      |                                           ~~~~~~~~~^~~~~~~~~
viewer.c: In function ‘render_text’:
viewer.c:385:53: warning: variable ‘b’ set but not used [-Wunused-but-set-variable]
  385 |         unsigned char *source, *dest, *dest2, r, g, b, pix_and = 255, v;
      |                                                     ^
viewer.c:385:50: warning: variable ‘g’ set but not used [-Wunused-but-set-variable]
  385 |         unsigned char *source, *dest, *dest2, r, g, b, pix_and = 255, v;
      |                                                  ^
viewer.c:385:47: warning: variable ‘r’ set but not used [-Wunused-but-set-variable]
  385 |         unsigned char *source, *dest, *dest2, r, g, b, pix_and = 255, v;
      |                                               ^
viewer.c: In function ‘delete_text’:
viewer.c:483:37: warning: unused parameter ‘widget’ [-Wunused-parameter]
  483 | static gint delete_text( GtkWidget *widget, GdkEvent *event, gpointer data )
      |                          ~~~~~~~~~~~^~~~~~
viewer.c:483:55: warning: unused parameter ‘event’ [-Wunused-parameter]
  483 | static gint delete_text( GtkWidget *widget, GdkEvent *event, gpointer data )
      |                                             ~~~~~~~~~~^~~~~
viewer.c:483:71: warning: unused parameter ‘data’ [-Wunused-parameter]
  483 | static gint delete_text( GtkWidget *widget, GdkEvent *event, gpointer data )
      |                                                              ~~~~~~~~~^~~~
viewer.c: In function ‘pressed_text’:
viewer.c:505:33: warning: unused parameter ‘menu_item’ [-Wunused-parameter]
  505 | void pressed_text( GtkMenuItem *menu_item, gpointer user_data )
      |                    ~~~~~~~~~~~~~^~~~~~~~~
viewer.c:505:53: warning: unused parameter ‘user_data’ [-Wunused-parameter]
  505 | void pressed_text( GtkMenuItem *menu_item, gpointer user_data )
      |                                            ~~~~~~~~~^~~~~~~~~
canvas.c:338:9: warning: ‘__builtin_strncpy’ output may be truncated copying 250 bytes from a string of length 299 [-Wstringop-truncation]
  338 |         strncpy( mem_filename, fname, 250 );
      |         ^
canvas.c: In function ‘fs_ok’:
canvas.c:603:9: warning: ‘__builtin_strncpy’ specified bound 256 equals destination size [-Wstringop-truncation]
  603 |         strncpy(fname, gtk_entry_get_text(GTK_ENTRY(
      |         ^
canvas.c:338:9: warning: ‘__builtin_strncpy’ output may be truncated copying 250 bytes from a string of length 255 [-Wstringop-truncation]
  338 |         strncpy( mem_filename, fname, 250 );
      |         ^
canvas.c: In function ‘file_selector’:
canvas.c:716:42: warning: ‘%s’ directive output may be truncated writing up to 259 bytes into a region of size 256 [-Wformat-truncation=]
  716 |                 else snprintf(txt, 256, "%s%c", fs_last_dir, DIR_SEP);
      |                                          ^~     ~~~~~~~~~~~
In file included from /usr/include/stdio.h:970,
                 from canvas.c:20:
In function ‘snprintf’,
    inlined from ‘file_selector’ at canvas.c:716:8:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output between 2 and 261 bytes into a destination of size 256
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
make[2]: Leaving directory '/build/reproducible-path/rgbpaint-0.8.7/src'
make[1]: *** [Makefile:8: src] Error 2
make[1]: Leaving directory '/build/reproducible-path/rgbpaint-0.8.7'
dh_auto_build: error: make -j8 returned exit code 2
make: *** [debian/rules:13: binary] Error 25
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2