[Bug middle-end/81876] [7 Regression] bogus -Wstrict-overflow warning with -O3

["bunk at stusta dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81876

--- Comment #6 from Adrian Bunk <bunk at stusta dot de> ---
(In reply to Jeffrey A. Law from comment #4)
> WRT locations/diagnostics for things like ldist where GCC conjures up code
> that has little resemblance to what the user wrote.  It's a real issue once
> we issue the warning -- the user has no clue what it meant.
> 
> On the other hand those warnings (particularly those that result from ldist)
> are highlighting real issues.  Bogus user code, poor optimization, even
> under-specified language from ISO.  Examples of all can be found in BZ.

If in doubt, don't issue any warning to the user.

As far as I am aware, the testcase in this bug does not warrant any warning in
that line - even "comparison is always true" would be wrong.

If a warning option sometimes generates bogus warnings for issues not present
in the code, the only reasonable option for a user would be to always disable
this warning.