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From: "redbeard0531 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/105534] New: -Wmaybe-uninitialized shouldn't suppress
 -Wuninitialized warnings
Date: Mon, 09 May 2022 12:22:06 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105534

            Bug ID: 105534
           Summary: -Wmaybe-uninitialized shouldn't suppress
                    -Wuninitialized warnings
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redbeard0531 at gmail dot com
  Target Milestone: ---

The following function emits a -Wuninitialized warning on ++count with -Wall
https://godbolt.org/z/KfaMEETY1:

int test(bool cond) {
    int count;
    ++count;
    return count;
}

Making the increment be conditional changes it to a -Wmaybe-uninitialized
warning, which is suppressed with -Wno-maybe-uninitialized.
https://godbolt.org/z/qarMrqW7E

int test(bool cond) {
    int count;
    if (cond) ++count;
    return count;
}

This makes no sense. count is never initialized on any path through the
function, and it is returned on all paths.

We use -Wall with -Wno-maybe-uninitialized on our codebase because we were
getting too many false-positives with -Wmaybe-initialized, in particular fr=
om
third-party headers that we didn't want to modify. At the time we decided t=
o do
that, we didn't realize that we would also be missing out on clearly
uninitialized cases like this.=