[Bug c++/104642] Add __builtin_trap() for missing return at -O0

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104642

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
PR 104884 is another "why is undefined behaviour so surprising?" case for
-funreachable-traps