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From: "mengli.ming at outlook dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug analyzer/108492] New: __analyzer_eval has effect on the
 analysis result of gcc static analyzer
Date: Mon, 23 Jan 2023 10:44:47 +0000
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X-Bugzilla-Type: new
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: analyzer
X-Bugzilla-Version: 13.0
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X-Bugzilla-Who: mengli.ming at outlook dot com
X-Bugzilla-Status: UNCONFIRMED
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X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: dmalcolm at gcc dot gnu.org
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D108492

            Bug ID: 108492
           Summary: __analyzer_eval has effect on the analysis result of
                    gcc static analyzer
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: mengli.ming at outlook dot com
  Target Milestone: ---

case:

```c
void __analyzer_eval();

void f(int b)
{
    int c =3D 1;
    __analyzer_eval(c && (c =3D 0) | b);
    if (c && (c =3D 0) | b)
    {
        int *p =3D (int *)0;
        __analyzer_eval(c && (c =3D 0) | b);
        if (c && (c =3D 0) | b)
        {
            *p =3D 42;
        }
    }
}

```

In this case, when `__analyzer_eval` is added at line 6
(https://godbolt.org/z/defnzqKPn), the eval statement inside the if branch =
has
no output. However, when line 6 is commented out
(https://godbolt.org/z/j4dGGEM1s), then the result is output.=20

Also, the eval result of `(c && (c =3D 0) | b)` should probably be TRUE aft=
er
analyzer goes inside the if branch.

Thank you for taking the time to review this case.=