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From: "eggert at cs dot ucla.edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114833] New:
 --suggest-attribute=returns_nonnull misdiagnoses functions with
 __attribute__((nonnull))
Date: Wed, 24 Apr 2024 05:36:40 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
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X-Bugzilla-Severity: normal
X-Bugzilla-Who: eggert at cs dot ucla.edu
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114833

            Bug ID: 114833
           Summary: --suggest-attribute=3Dreturns_nonnull misdiagnoses
                    functions with __attribute__((nonnull))
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: eggert at cs dot ucla.edu
  Target Milestone: ---

This is gcc (GCC) 14.0.1 20240411 (Red Hat 14.0.1-0) on Fedora 40 x86-64. P=
ut
this code into the file t.i:

  extern char const *foo () __attribute__ ((returns_nonnull));
  char const *
  foo ()
  {
    return "abc";
  }

and compile it with:

  gcc -S -O2 -Wsuggest-attribute=3Dreturns_nonnull t.i

The output is:

  t.i: In function =E2=80=98foo=E2=80=99:
  t.i:3:3: warning: function might be candidate for attribute =E2=80=98retu=
rns_nonnull=E2=80=99
[-Wsuggest-attribute=3Dreturns_nonnull]
      3 |   foo ()
        |   ^~~

This diagnostic is obviously wrong, as foo is already declared with the
suggested attribute.=