build fails on Fedora 40

[es-fabricemarie]

Hi,
When building on Fedora40, I'm getting this error:

g++ -Wall -Wextra -Werror -O3 -I../include -D_FILE_OFFSET_BITS=64 -std=c++11 -Wold-style-cast -Wno-missing-field-initializers -O2 -flto=auto -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall -Werror=format-security -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -m64 -march=x86-64 -mtune=generic -fasynchronous-unwind-tables -fstack-clash-protection -fcf-protection -fno-omit-frame-pointer -mno-omit-leaf-frame-pointer  -L../lib -Wl,-z,relro -Wl,--as-needed  -Wl,-z,pack-relative-relocs -Wl,-z,now -specs=/usr/lib/rpm/redhat/redhat-hardened-ld-errors -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1  -Wl,--build-id=sha1 -specs=/usr/lib/rpm/redhat/redhat-package-notes  -o ../bin/bees bees.o bees-context.o bees-hash.o bees-resolve.o bees-roots.o bees-thread.o bees-trace.o bees-types.o bees-version.o bees-usage.o ../lib/libcrucible.a -lcrucible -lpthread
In member function ‘__ct ’,
    inlined from ‘__ct ’ at bees-trace.cc:53:2,
    inlined from ‘operator()’ at bees-roots.cc:764:4,
    inlined from ‘__invoke_impl’ at /usr/include/c++/14/bits/invoke.h:61:36,
    inlined from ‘__invoke_r’ at /usr/include/c++/14/bits/invoke.h:150:33,
    inlined from ‘_M_invoke’ at /usr/include/c++/14/bits/std_function.h:290:30:
/usr/include/c++/14/bits/std_function.h:391:17: error: ‘<anonymous>’ may be used uninitialized [-Werror=maybe-uninitialized]
  391 |             __x._M_manager(_M_functor, __x._M_functor, __clone_functor);
      |                 ^
/usr/include/c++/14/bits/std_function.h: In function ‘_M_invoke’:
/usr/include/c++/14/bits/std_function.h:267:7: note: by argument 2 of type ‘const union _Any_data & {ref-all}’ to ‘_M_manager’ declared here
  267 |       _M_manager(_Any_data& __dest, const _Any_data& __source,
      |       ^
bees-roots.cc:764:25: note: ‘<anonymous>’ declared here
  764 |                         BEESTRACE("calling transid_max_nocache");
      |                         ^
lto1: all warnings being treated as errors
make[2]: *** [/tmp/cc47wSlM.mk:23: /tmp/cc8Lchk2.ltrans7.ltrans.o] Error 1
make[2]: *** 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
make[1]: *** [Makefile:43: ../bin/bees] Error 1
make[1]: Leaving directory '/home/builduser/rpmbuild/BUILD/bees/src'
make: *** [Makefile:39: src] Error 2

Looks like the default configuration on Fedora40 compiler is pretty strict.
I could remove the -Werror=maybe-uninitialized flag of course, but it defeats the purpose.

Hope this helps.

[Zygo]

That looks more like a library or toolchain issue. If it's real, we probably don't want to run the resulting binary. If it's not real, it's up to the toolchain maintainers to fix.

BEESTRACE is used everywhere in bees, and it would be disastrous if it's reading uninitialized data.

[Zygo]

I tried reproducing this on a freshly updated 40...

[root@localhost bees]# cat /etc/fedora-release 
Fedora release 40 (Forty)
[root@localhost bees]# g++ --version
g++ (GCC) 14.2.1 20240912 (Red Hat 14.2.1-3)

The g++ is newer than this issue. Does it still happen? Is there anything required to reproduce except make -j10?