Hi,

qt6-webengine fails to build in a test rebuild on at least amd64 and arm64 with
gcc-16/g++-16, but builds properly with gcc-15/g++-15. The severity of this
report will be raised before the forky release.

The full build log can be found at:
https://people.debian.org/~ema/gcc-16-rebuilds/output-1/qt6-webengine_arm64.build.xz

The last lines of the build log are at the end of this report.

To build with GCC 16, either set CC=gcc-16 CXX=g++-16 explicitly,
or install the gcc, g++, gfortran, ... packages from experimental.

  apt-get -t=experimental install g++

Common build failures include unused (but set) variables, array subscripts
partly outside array bounds, and new/dropped symbols in Debian symbols files.
For other C/C++ related build failures see the porting guide at
http://gcc.gnu.org/gcc-16/porting_to.html

Please only close this issue after double-checking that the package can be
built correctly with GCC 16.

Please do not reassign this bug to another package. If a fix in another package
is required, then file a bug for the other package (or clone), and mark this
bug as blocked by the bug in the other package.

[...]


jumbo_build_excluded=["browser"]
jumbo_file_merge_limit=8
ozone_auto_platforms=false
pdf_enable_fontations=false
pdf_enable_v8=false
pdf_enable_xfa=false
pdf_enable_xfa_bmp=false
pdf_enable_xfa_gif=false
pdf_enable_xfa_png=false
pdf_enable_xfa_tiff=false
pdfium_use_qt_libpng=false
pdfium_use_system_libpng=true
pdfium_use_system_libtiff=true
pdfium_use_system_zlib=true
pkg_config="/usr/bin/pkg-config"
qt_freetype_config="/build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/pdf/None/aarch64:qt_freetype_config"
qt_harfbuzz_config="/build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/pdf/None/aarch64:qt_harfbuzz_config"
qt_libjpeg_config="/build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/pdf/None/aarch64:qt_libjpeg_config"
qt_libpng_config="/build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/pdf/None/aarch64:qt_libpng_config"
qtwebengine_target="/build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/pdf/None/aarch64:QtPdf"
strip_absolute_paths_from_debug_symbols=false
treat_warnings_as_errors=false
use_allocator_shim=false
use_cups=false
use_custom_libcxx=false
use_custom_libcxx_for_host=false
use_dawn=false
use_freelist_dispatcher=false
use_gio=false
use_glib=false
use_gold=false
use_jumbo_build=true
use_lld=false
use_ml=false
use_ml_inliner=false
use_mold=false
use_nss_certs=false
use_partition_alloc=true
use_partition_alloc_as_malloc=false
use_qt_freetype=false
use_qt_harfbuzz=false
use_qt_libjpeg=false
use_sysroot=false
use_system_icu=true
use_system_libopenjpeg2=true
use_system_libpng=true
use_system_zlib=true
use_thin_lto=false
use_udev=false
use_v8_context_snapshot=false
use_xkbcommon=false
v8_enable_webassembly=false
v8_symbol_level=0
v8_use_external_startup_data=false
v8_use_external_startup_data=false
webnn_use_tflite=false
-- GN *********************************************************************
WARNING: Support for linking against a C++ standard library other
  than the one in-tree (buildtools/third_party/libc++) is deprecated
  and support for this will end. We plan to remove this option in
  M138.
*********************************************************************
Done. Made 24470 targets from 3553 files in 28389ms
FAILED: [code=1] src/core/None/aarch64/QtWebEngineCore.stamp src/core/None/aarch64/obj/tools/v8_context_snapshot/v8_context_snapshot.stamp src/core/None/aarch64/QtWebEngineCore /build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/core/None/aarch64/QtWebEngineCore.stamp /build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/core/None/aarch64/obj/tools/v8_context_snapshot/v8_context_snapshot.stamp /build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/core/None/aarch64/QtWebEngineCore
cd /build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/core && /usr/bin/ninja -v -C /build/reproducible-path/qt6-webengine-6.10.2+dfsg/obj-aarch64-linux-gnu/src/core/None/aarch64 QtWebEngineCore
ninja: build stopped: subcommand failed.
dh_auto_build: error: cd obj-aarch64-linux-gnu && LC_ALL=C.UTF-8 ninja -j128 -v returned exit code 1
make[1]: *** [debian/rules:81: override_dh_auto_build] Error 25
make[1]: Leaving directory '/build/reproducible-path/qt6-webengine-6.10.2+dfsg'
make: *** [debian/rules:35: binary] Error 2
dpkg-buildpackage: error: debian/rules binary subprocess failed with exit status 2