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From: "xry111 at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/111669] bogus -Wnonnull in conditionally executed
 code
Date: Thu, 05 Oct 2023 06:14:37 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111669

Xi Ruoyao <xry111 at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement

--- Comment #7 from Xi Ruoyao <xry111 at gcc dot gnu.org> ---
(In reply to Zeb Figura from comment #6)
> It is my impression that gcc is interested in avoiding false positives for
> its warnings.

Correct, but we are also interested in avoiding false negatives.  Without e=
xtra
information provided by something like __builtin_unreachable, any change
decreasing false positives will increase false negatives (unless the false
positive is completely stupid: for the simplified test case I think the fal=
se
positive not completely stupid, but maybe it is completely stupid for your
original program).

> It is also my impression that -Wnonnull is not *supposed* to emit warnings
> for cases where, from the compiler's point of view, NULL might be passed,
> but some high-level invariant prevents this. Compare -Wmaybe-uninitialize=
d,
> where the documentation clearly specifies otherwise.

Maybe we can separate -Wnonnull into -Wmaybe-nonnull and -Wnonnull, or just
make -Wnonnull not to emit warnings for conditional paths and tell users
expecting a nonnull warning in conditional paths to use the analyzer (it's =
very
supposed to warn even in conditional paths) instead.

> If both of these impressions are incorrect, this bug report can be closed=
 as
> WONTFIX.

I'll keep it open but make it an enhancement.=