[Bug lto/83954] [6/7/8 Regression] LTO: Bogus -Wlto-type-mismatch warning for array of pointer to incomplete type

["marxin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83954

--- Comment #6 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Dan Bonachea from comment #5)
> (In reply to Martin Liška from comment #4)
> > > Assuming it's the latter, can anyone suggest any non-intrusive workarounds?
> > > (aside from the obvious "big hammers" of -fno-lto or -fno-strict-aliasing)
> > 
> > Yes, the warning should not produce bogus warnings. Proper solution is not
> > to break strict aliasing. Note that it can help optimization to make more
> > aggressive optimizations.
> 
> I'm confused - are you saying the test program actually breaks C's strict
> aliasing rules? My understanding was this is a correct (spec-compliant) C
> program that is being mishandled by gcc. My question was whether this
> mishandling could generally result in actual incorrect optimization of
> programs encountering this defect, and it sounds like you are saying it
> might?

Yes, it's a valid C program. And yes, it's mishandled by GCC. I believe
considering these two types as having different alias sets can result in an
incorrect optimization.