[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/daemontools_0.76-13.1_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

[...]
LANG=C.UTF-8
LC_ALL=C.UTF-8
LOGNAME=user42
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
SHELL=/bin/sh
USER=user42

dpkg-buildpackage
-----------------

Command: dpkg-buildpackage --sanitize-env -us -uc -b
dpkg-buildpackage: info: source package daemontools
dpkg-buildpackage: info: source version 1:0.76-13.1
dpkg-buildpackage: info: source distribution unstable
dpkg-buildpackage: info: source changed by David Bremner <bremner@debian.org>
 dpkg-source --before-build .
dpkg-buildpackage: info: host architecture amd64
 debian/rules clean
dh clean
   debian/rules override_dh_auto_clean
make[1]: Entering directory '/build/reproducible-path/daemontools-0.76'
dh_auto_clean
rm -rf 'daemontools-0.76/compile'
rm -rf 'daemontools-0.76/command'
make[1]: Leaving directory '/build/reproducible-path/daemontools-0.76'
   dh_clean
 debian/rules binary
dh binary
   dh_update_autotools_config
   dh_autoreconf
   debian/rules override_dh_auto_build
make[1]: Entering directory '/build/reproducible-path/daemontools-0.76'
# create compile directory
mkdir -p 'daemontools-0.76/compile/debian'
# svscanboot.sh: /command/svc -> svc, /service -> /etc/service
sed -e 's}/command/svc}svc};s}/service}/etc/service}g' < 'daemontools-0.76/src/svscanboot.sh' > 'daemontools-0.76/compile/debian/svscanboot.sh'
cd 'daemontools-0.76/compile' && ln -s debian/svscanboot.sh svscanboot.sh
# debian CFLAGS + CPPFLAGS
echo 'cc -g -O2 -Werror=implicit-function-declaration -ffile-prefix-map=/build/reproducible-path/daemontools-0.76=. -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -Wdate-time -D_FORTIFY_SOURCE=2' > 'daemontools-0.76/compile/debian/conf-cc'
cd 'daemontools-0.76/compile' && ln -s debian/conf-cc conf-cc
# debian LDFLAGS
echo 'cc -Wl,-z,relro -Wl,-z,now' > 'daemontools-0.76/compile/debian/conf-ld'
cd 'daemontools-0.76/compile' && ln -s debian/conf-ld conf-ld
# build
cd 'daemontools-0.76' && package/compile
Linking ./src/* into ./compile...
Compiling everything in ./compile...
make[2]: Entering directory '/build/reproducible-path/daemontools-0.76/daemontools-0.76/compile'
sh find-systype.sh > systype
rm -f compile
sh print-cc.sh > compile
chmod 555 compile
./compile byte_chr.c
byte_chr.c: In function ‘byte_chr’:
byte_chr.c:5:14: warning: old-style function definition [-Wold-style-definition]
    5 | unsigned int byte_chr(s,n,c)
      |              ^~~~~~~~
byte_chr.c:9:1: error: number of arguments doesn’t match prototype
    9 | {
      | ^
In file included from byte_chr.c:3:
byte.h:6:21: error: prototype declaration
    6 | extern unsigned int byte_chr();
      |                     ^~~~~~~~
make[2]: *** [Makefile:65: byte_chr.o] Error 1
make[2]: Leaving directory '/build/reproducible-path/daemontools-0.76/daemontools-0.76/compile'
make[1]: *** [debian/rules:22: override_dh_auto_build] Error 2
make[1]: Leaving directory '/build/reproducible-path/daemontools-0.76'
make: *** [debian/rules:32: binary] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess returned exit status 2