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From: "clyon at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/97108] New: Wmaybe-uninitialized false positive
Date: Fri, 18 Sep 2020 12:32:12 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.0
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X-Bugzilla-Severity: normal
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97108

            Bug ID: 97108
           Summary: Wmaybe-uninitialized false positive
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: clyon at gcc dot gnu.org
  Target Milestone: ---

This testcase causes a false positive 'may be used uninitialized' warning w=
hen
compiled with -O2 -Wall. It is derived from libiberty/pex-win32.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2

int _close(int);

int
pex_win32_exec_child (int flags,
                      int in, int out, int errdes)
{
  int pid =3D flags;
  int orig_err;
  int separate_stderr =3D !(flags);

  if (separate_stderr)
    {
      orig_err =3D errdes;
    }

  if (pid !=3D (int) -1)
    {
      if (in !=3D STDIN_FILENO)
        _close (in);
      if (out !=3D STDOUT_FILENO)
        _close (out);
      if (separate_stderr
          && orig_err !=3D STDERR_FILENO)
        _close (orig_err);
    }

  return pid;
}
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

../pex-win32.c: In function =E2=80=98pex_win32_exec_child=E2=80=99:
../pex-win32.c:27:23: warning: =E2=80=98orig_err=E2=80=99 may be used unini=
tialized in this
function [-Wmaybe-uninitialized]
   27 |           && orig_err !=3D STDERR_FILENO)
      |                       ^=