[Bug c/37178] New: false positive with -Wstrict-overflow=2 on code not involving signed overflow

[Bug c/37178] New: false positive with -Wstrict-overflow=2 on code not involving signed overflow

[edwintorok at gmail dot com]

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Using gcc version 4.3.1 (Debian 4.3.1-9) on amd64 I get a warning I shouldn't:
$ gcc -O2 -Wstrict-overflow=2 testcase-min.i -c
testcase-min.i: In function ‘cli_scanrar’:
testcase-min.i:40: warning: assuming signed overflow does not occur when
simplifying conditional to constant

At line 40 there is this (ret is int, but  it only gets values assigned, no
arithmetic is performed on it)
if(ret == 2)  ret = 0;

I am attaching the reduced testcase.

More system info:
$ uname -a
Linux lightspeed2 2.6.26-1-amd64 #1 SMP Fri Aug 8 13:17:41 UTC 2008 x86_64
GNU/Linux
$ gcc -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.3.1-9'
--with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared
--with-system-zlib --libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3
--program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug
--enable-objc-gc --enable-mpfr --enable-cld --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.3.1 (Debian 4.3.1-9)


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           Summary: false positive with -Wstrict-overflow=2 on code not
                    involving signed overflow
           Product: gcc
           Version: 4.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: edwintorok at gmail dot com
 GCC build triplet: x86_64-linux-gnu
  GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37178

[Bug c/37178] false positive with -Wstrict-overflow=2 on code not involving signed overflow

[edwintorok at gmail dot com]

------- Comment #1 from edwintorok at gmail dot com  2008-08-20 17:52 -------
Created an attachment (id=16115)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=16115&action=view)
reduced testcase

the testcase is reduced from clamav's scanners.c


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37178

[Bug c/37178] false positive with -Wstrict-overflow=2 on code not involving signed overflow

[manu at gcc dot gnu dot org]

-- 

manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |manu at gcc dot gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-08-21 16:51:54
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37178

[Bug c/37178] false positive with -Wstrict-overflow=2 on code not involving signed overflow

[manu at gcc dot gnu dot org]

------- Comment #2 from manu at gcc dot gnu dot org  2008-08-21 16:53 -------
This happens also in trunk.


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manu at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |iant at google dot com
   Last reconfirmed|2008-08-21 16:51:54         |2008-08-21 16:53:46
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37178