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From: "cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/107411] trivial-auto-var-init=zero invalid
 uninitialized variable warning
Date: Tue, 28 Feb 2023 17:11:31 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107411

--- Comment #14 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Qing Zhao <qinzhao@gcc.gnu.org>:

https://gcc.gnu.org/g:afe6cea4489846aa8585f3c045d16cdaa08cc6cd

commit r13-6379-gafe6cea4489846aa8585f3c045d16cdaa08cc6cd
Author: Qing Zhao <qing.zhao@oracle.com>
Date:   Tue Feb 28 17:11:05 2023 +0000

    Fixing PR107411

    This is a bug in tree-ssa-uninit.cc.
    When doing the following:

      /* Ignore the call to .DEFERRED_INIT that define the original
         var itself as the following case:
           temp =3D .DEFERRED_INIT (4, 2, =C3=A2alt_reloc");
           alt_reloc =3D temp;
         In order to avoid generating warning for the fake usage
         at alt_reloc =3D temp.
      */

    We need to compare the var name inside the .DEFERRED_INIT call
    (the 3rd argument) and the name for the LHS variable. if they are the s=
ame,
    we will NOT report the warning.

    There is one issue when we get the name for the LHS variable. when the
    variable doesn't have a DECL_NAME (it's not a user declared variable,
    which is the case for this bug):

      _1 =3D .DEFERRED_INIT (4, 2, &"D.2389"[0]);
      D.2389 =3D _1;

    The current checking just ignores this case, and still report the warni=
ng.

    The fix is very simple, when getting the name for the LHS variable, we
should
    consider this case and come up with the name the same way as we constru=
ct
the
    3rd argument for the call to .DEFERRED_INIT (please refer to the routine
    "gimple_add_init_for_auto_var")

            PR middle-end/107411

    gcc/ChangeLog:

            PR middle-end/107411
            * gimplify.cc (gimple_add_init_for_auto_var): Use sprintf to
replace
            xasprintf.
            * tree-ssa-uninit.cc (warn_uninit): Handle the case when the
            LHS varaible of a .DEFERRED_INIT call doesn't have a DECL_NAME.

    gcc/testsuite/ChangeLog:

            PR middle-end/107411
            * g++.dg/pr107411.C: New test.=