[Bug c/68971] -Woverflow false alarm in code unreachable after __builtin_mul_overflow

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68971

--- Comment #7 from Martin Sebor <msebor at gcc dot gnu.org> ---
I didn't mean to sound like I was lecturing you, just trying to draw a clear
distinction between the cases.

Perhaps what's needed is for GCC to treat the builtins as constant expressions
when they're invoked with them as operands.  If you agree with that approach, I
suggest closing this bug and opening a new one with that request.

FWIW, in my experience, because sophisticated warnings that try to avoid
issuing false positives for unreachable code (e.g., -Wmaybe-uninutialized)
depend on optimizations they tend to be inconsistent not only between
optimization settings but also between different targets.  That in turn causes
hard to prevent build failures for the same code, which prompts some
people/teams to disable them altogether.