Build failures with the default -O3 in plucky

[Saviq]

So, as we've noticed, the default flags are becoming -O3 in plucky, and failures there are probably some sort of bug that we have (or, maybe, is a toolchain bug that should be filed). I don't mind dropping to -O2 temporarily, but we should also work out what's wrong.

Originally posted by @RAOF in #3691 (comment)

---

To reproduce:

lxc launch ubuntu-daily:plucky plucky
lxc shell plucky
apt update
git clone --depth=1 https://github.com/canonical/mir.git
cd mir
apt-get build-dep ./
dpkg-buildpackage -uc -us
# when it fails
cd build-amd64
# iterate here

[Saviq]

At least:

[ 61%] Building CXX object src/platforms/atomic-kms/server/kms/CMakeFiles/mirplatformgraphicsatomickms.dir/platform_symbols.cpp.o
cd /<<PKGBUILDDIR>>/build-amd64/src/platforms/atomic-kms/server/kms && /usr/bin/c++ -DBOOST_ATOMIC_DYN_LINK -DBOOST_ATOMIC_NO_LIB -DBOOST_FILESYSTEM_DYN_LINK -DBOOST_FILESYSTEM_NO_LIB -DBOOST_IOSTREAMS_DYN_LINK -DBOOST_IOSTREAMS_NO_LIB -DBOOST_PROGRAM_OPTIONS_DYN_LINK -DBOOST_PROGRAM_OPTIONS_NO_LIB -DBOOST_SYSTEM_DYN_LINK -DBOOST_SYSTEM_NO_LIB -DEGL_NO_X11 -DLTTNG_UST_HAVE_SDT_INTEGRATION -DMIR_LOG_COMPONENT_FALLBACK=\"atomic-kms\" -DMIR_USE_APPARMOR -DMIR_VERSION_MAJOR=2 -DMIR_VERSION_MICRO=2 -DMIR_VERSION_MINOR=19 -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D__GBM__ -Dmirplatformgraphicsatomickms_EXPORTS -I/<<PKGBUILDDIR>>/include/renderers/gl -I/<<PKGBUILDDIR>>/include/renderers/sw -I/<<PKGBUILDDIR>>/include/common -I/<<PKGBUILDDIR>>/src/platforms/common/server -I/<<PKGBUILDDIR>>/src/platforms/atomic-kms/server/kms/.. -I/<<PKGBUILDDIR>>/build-amd64/src/platforms/atomic-kms/server/kms/.. -I/<<PKGBUILDDIR>>/build-amd64/src/platform/graphics -I/<<PKGBUILDDIR>>/include/platform -I/<<PKGBUILDDIR>>/include/wayland -I/<<PKGBUILDDIR>>/src/include/wayland -I/<<PKGBUILDDIR>>/build-amd64/src/wayland -I/<<PKGBUILDDIR>>/include/core -I/<<PKGBUILDDIR>>/build-amd64/src/platforms/atomic-kms/server -isystem /usr/include/libdrm -g -O3 -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer -ffile-prefix-map=/<<PKGBUILDDIR>>=. -flto=auto -ffat-lto-objects -fstack-protector-strong -fstack-clash-protection -Wformat -Werror=format-security -fcf-protection -fdebug-prefix-map=/<<PKGBUILDDIR>>=/usr/src/mir-2.19.2+dev25-g9e4f214b9c-0ubuntu25.04 -Wdate-time -D_FORTIFY_SOURCE=3 -pthread -g -Wall -fno-strict-aliasing  -Wnon-virtual-dtor -Wextra -fPIC -Werror -Wno-mismatched-tags -Wno-psabi -std=c++23 -fPIC -MD -MT src/platforms/atomic-kms/server/kms/CMakeFiles/mirplatformgraphicsatomickms.dir/platform_symbols.cpp.o -MF CMakeFiles/mirplatformgraphicsatomickms.dir/platform_symbols.cpp.o.d -o CMakeFiles/mirplatformgraphicsatomickms.dir/platform_symbols.cpp.o -c /<<PKGBUILDDIR>>/src/platforms/atomic-kms/server/kms/platform_symbols.cpp
In member function ‘__dt_base ’,
    inlined from ‘__dt_base ’ at /usr/include/c++/14/bits/shared_ptr_base.h:1525:7,
    inlined from ‘__dt_base ’ at /usr/include/c++/14/bits/shared_ptr.h:175:11,
    inlined from ‘_M_destroy’ at /usr/include/c++/14/optional:283:35,
    inlined from ‘_M_reset’ at /usr/include/c++/14/optional:314:14,
    inlined from ‘__dt_base ’ at /usr/include/c++/14/optional:437:65,
    inlined from ‘__dt_base ’ at /usr/include/c++/14/optional:508:12,
    inlined from ‘__dt_base ’ at /usr/include/c++/14/optional:703:11,
    inlined from ‘__dt_base ’ at /usr/src/mir-2.19.2+dev25-g9e4f214b9c-0ubuntu25.04/src/server/shell/decoration/input.h:166:12,
    inlined from ‘_M_destroy’ at /usr/include/c++/14/optional:283:35,
    inlined from ‘_M_reset’ at /usr/include/c++/14/optional:314:14,
    inlined from ‘_M_reset’ at /usr/include/c++/14/optional:311:0,
    inlined from ‘_M_reset’ at /usr/include/c++/14/optional:466:53,
    inlined from ‘operator=’ at /usr/include/c++/14/optional:832:16,
    inlined from ‘pointer_leave’ at /usr/src/mir-2.19.2+dev25-g9e4f214b9c-0ubuntu25.04/src/server/shell/decoration/input.cpp:309:20,
    inlined from ‘input_consumed’ at /usr/src/mir-2.19.2+dev25-g9e4f214b9c-0ubuntu25.04/src/server/shell/decoration/input.cpp:74:39:
/usr/include/c++/14/bits/shared_ptr_base.h:1068:13: error: ‘MEM[(struct __shared_count *)_3 + 208B]._M_pi’ may be used uninitialized [-Werror=maybe-uninitialized]
 1068 |         if (_M_pi != nullptr)
      |             ^
lto1: all warnings being treated as errors
make[4]: *** [/tmp/ccdqFeA7.mk:104: /tmp/ccBsRV7S.ltrans34.ltrans.o] Error 1
make[4]: *** Waiting for unfinished jobs....
lto-wrapper: fatal error: make returned 2 exit status
compilation terminated.
/usr/bin/ld: error: lto-wrapper failed
collect2: error: ld returned 1 exit status

https://launchpadlibrarian.net/769547850/buildlog_ubuntu-plucky-amd64.mir_2.19.2+dev25-g9e4f214b9c-0ubuntu25.04_BUILDING.txt.gz
https://launchpadlibrarian.net/769549070/buildlog_ubuntu-plucky-ppc64el.mir_2.19.2+dev25-g9e4f214b9c-0ubuntu25.04_BUILDING.txt.gz

[Saviq]

On arm64:

/usr/bin/ld: ../libmir-test-assist.a(mmap_wrapper.cpp.o): in function `std::literals::string_literals::operator"" s[abi:cxx11](char const*, unsigned long)':
/usr/include/c++/14/bits/basic_string.h:4694:(.text+0x650): undefined reference to `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, unsigned long, std::allocator<char> const&)'
/usr/bin/ld: /usr/include/c++/14/bits/basic_string.h:4694:(.text+0xa68): undefined reference to `std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, unsigned long, std::allocator<char> const&)'
collect2: error: ld returned 1 exit status

https://launchpadlibrarian.net/769549434/buildlog_ubuntu-plucky-arm64.mir_2.19.2+dev25-g9e4f214b9c-0ubuntu25.04_BUILDING.txt.gz

[Saviq]

armhf builds, but a test fails:

[ RUN ] UdevWrapperTest.UdevMonitorDoesNotTriggerBeforeEnabling
./tests/unit-tests/test_udev_wrapper.cpp:330: Failure
Value of: event_handler_called
Actual: true
Expected: false

https://launchpadlibrarian.net/769549446/buildlog_ubuntu-plucky-armhf.mir_2.19.2+dev25-g9e4f214b9c-0ubuntu25.04_BUILDING.txt.gz