From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id E3BE63858C53; Sun, 19 Mar 2023 12:15:57 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E3BE63858C53
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1679228157;
	bh=jhepRbWfdo2GMzgUA4R0pihuI5g0Wr9KgEXkx/lYPFM=;
	h=From:To:Subject:Date:From;
	b=t5AXGFtjIRArSOCroi7Cy8ptwlQBe6IO3hCTud+TI/U9CEf8XngTmGlN0UAGR6tuy
	 ok3GZivt/dczCQ1Y+/cYRsGj6j+VVtUQn6GbNruDjra3ilJivBHahs8ApsSBXJeinv
	 2n1kCv/4qIfRgtjgvO9ZF5PrfrVcodtKVOEa7MWI=
From: "geoffreydgr at icloud dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug analyzer/109193] New: GCC Static Analyzer does not know 1-a >
 0-b" in the true branch of "if (a < b && 0 < a) "
Date: Sun, 19 Mar 2023 12:15:57 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: analyzer
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: geoffreydgr at icloud dot com
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: dmalcolm at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-109193-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109193

            Bug ID: 109193
           Summary: GCC Static Analyzer does not know 1-a > 0-b" in the
                    true branch of "if (a < b && 0 < a) "
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: analyzer
          Assignee: dmalcolm at gcc dot gnu.org
          Reporter: geoffreydgr at icloud dot com
  Target Milestone: ---

I found a problem that GCC Static Analyzer does not know 1-a > 0-b" (line 1=
2)
in the true branch of "if (a < b && 0 < a) ", but it knows =E2=80=9C0-a > 0=
-b" (line
11) .

I run gcc (trunk) with options -fanalyzer -O0.

See it live: https://godbolt.org/z/6MjobMqnM

Input:
```
#include <stdint.h>
#include <stdbool.h>

int foo(int a, int b) {
    if ((a<b) && (0 < a)){
        //Negation
        __analyzer_eval(!(a<b) =3D=3D false);=20
        __analyzer_eval(-a > -b);

        // Add a positive number after the negation
        __analyzer_eval(0-a > 0-b);
        __analyzer_eval(1-a > 0-b);
        __analyzer_eval(1-a > 1-b);
        __analyzer_eval(2-a > 0-b);
        __analyzer_eval(2-a > 1-b);
        __analyzer_eval(2-a > 2-b);

    }
}
```


Output:
```
<source>: In function 'foo':
<source>:7:9: warning: implicit declaration of function '__analyzer_eval'
[-Wimplicit-function-declaration]
    7 |         __analyzer_eval(!(a<b) =3D=3D false);
      |         ^~~~~~~~~~~~~~~
<source>:7:9: warning: TRUE
    7 |         __analyzer_eval(!(a<b) =3D=3D false);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:8:9: warning: TRUE
    8 |         __analyzer_eval(-a > -b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~
<source>:11:9: warning: TRUE
   11 |         __analyzer_eval(0-a > 0-b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:12:9: warning: UNKNOWN
   12 |         __analyzer_eval(1-a > 0-b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:13:9: warning: TRUE
   13 |         __analyzer_eval(1-a > 1-b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:14:9: warning: UNKNOWN
   14 |         __analyzer_eval(2-a > 0-b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:15:9: warning: UNKNOWN
   15 |         __analyzer_eval(2-a > 1-b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
<source>:16:9: warning: TRUE
   16 |         __analyzer_eval(2-a > 2-b);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 0
```=