Bug#1143716: veyon: FTBFS: /usr/include/x86_64-linux-gnu/qt6/QtCore/qregularexpression.h:31:21: error: defining 'QRegularExpression', which previously failed to be complete in a SFINAE context [-Werror=sfinae-incomplete=]

Package: src:veyon
Version: 4.9.7+repack1-1.1
Severity: serious
Tags: ftbfs forky sid

Dear maintainer:

During a rebuild of all packages in unstable, this package failed to build.

Below you will find the last part of the build log (probably the most
relevant part, but not necessarily). If required, the full build log
is available here:

https://people.debian.org/~sanvila/build-logs/202608/

About the archive rebuild: The build was made on virtual machines from AWS,
using sbuild and a reduced chroot with only build-essential packages.

If you cannot reproduce the bug please contact me privately, as I
am willing to provide ssh access to a virtual machine where the bug is
fully reproducible.

If this is really a bug in one of the build-depends, please use
reassign and add an affects on src:veyon, so that this is still
visible in the BTS web page for this package.

Thanks.

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[...]
[ 27%] Building CXX object plugins/ldap/kldap/CMakeFiles/kldap-light.dir/__/__/__/3rdparty/kldap/src/core/ldapdn.cpp.o
cd /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/plugins/ldap/kldap  [too-long-redacted] party/kldap/src/core/ldapdn.cpp
In file included from /usr/include/x86_64-linux-gnu/qt6/QtCore/qcborvalue.h:13,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qjsonvalue.h:8,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qjsonobject.h:8,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/QJsonObject:1,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/UVLADIE3JM/../../../../core/src/AccessControlRule.h:28,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/UVLADIE3JM/../../../../core/src/AccessControlProvider.h:27,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/UVLADIE3JM/moc_AccessControlProvider.cpp:9,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/mocs_compilation.cpp:3:
/usr/include/x86_64-linux-gnu/qt6/QtCore/qregularexpression.h:31:21: error: defining ‘QRegularExpression’, which previously failed to be complete in a SFINAE context [-Werror=sfinae-incomplete=]
   31 | class Q_CORE_EXPORT QRegularExpression
      |                     ^~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/16/unordered_map:44,
                 from /usr/include/c++/16/functional:80,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qcomparehelpers.h:28,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qcompare.h:639,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qnamespace.h:13,
                 from /usr/include/x86_64-linux-gnu/qt6/QtCore/qobjectdefs.h:12,
                 from /usr/include/x86_64-linux-gnu/qt6/QtGui/qwindowdefs.h:8,
                 from /usr/include/x86_64-linux-gnu/qt6/QtWidgets/qwidget.h:9,
                 from /usr/include/x86_64-linux-gnu/qt6/QtWidgets/qdialog.h:9,
                 from /usr/include/x86_64-linux-gnu/qt6/QtWidgets/QDialog:1,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/UVLADIE3JM/../../../../core/src/AboutDialog.h:27,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/UVLADIE3JM/moc_AboutDialog.cpp:9,
                 from /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/core/veyon-core_autogen/mocs_compilation.cpp:2:
/usr/include/c++/16/bits/range_access.h:325:24: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
  325 |     -> decltype(__cont.data())
      |                 ~~~~~~~^~~~
[ 28%] Building CXX object plugins/ldap/kldap/CMakeFiles/kldap-light.dir/KLdapIntegration.cpp.o
cd /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/plugins/ldap/kldap  [too-long-redacted] ldap/kldap/KLdapIntegration.cpp
[ 28%] Linking CXX shared library libkldap-light.so
cd /<<PKGBUILDDIR>>/obj-x86_64-linux-gnu/plugins/ldap/kldap && /usr/bin/cmake -E cmake_link_script CMakeFiles/kldap-light.dir/link.txt --verbose=1
cc1plus: all warnings being treated as errors
make[3]: *** [core/CMakeFiles/veyon-core.dir/build.make:149: core/CMakeFiles/veyon-core.dir/veyon-core_autogen/mocs_compilation.cpp.o] Error 1
make[3]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
make[2]: *** [CMakeFiles/Makefile2:983: core/CMakeFiles/veyon-core.dir/all] Error 2
make[2]: *** Waiting for unfinished jobs....
/usr/bin/x86_64-linux-gnu-g++ -fPIC -g -O2 -ffile-prefix-map [too-long-redacted] ib/x86_64-linux-gnu/libsasl2.so
make[3]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
[ 28%] Built target kldap-light
make[2]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
make[1]: *** [Makefile:159: all] Error 2
make[1]: Leaving directory '/<<PKGBUILDDIR>>/obj-x86_64-linux-gnu'
dh_auto_build: error: cd obj-x86_64-linux-gnu && make -j2 INSTALL="install --strip-program=true" VERBOSE=1 returned exit code 2
make: *** [debian/rules:23: binary] Error 25
dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2
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