[Bug c++/50158] New: [4.7 Regression] invalid 'variable set but not used' warning (boolean used as index to an array)

[Bug c++/50158] New: [4.7 Regression] invalid 'variable set but not used' warning (boolean used as index to an array)

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

             Bug #: 50158
           Summary: [4.7 Regression] invalid 'variable set but not used'
                    warning (boolean used as index to an array)
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 25080
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25080
reduced testcase

Compiler output:
$ gcc -Wunused-but-set-variable testcase.cpp -c
testcase.cpp: In function 'int foo(int)':
testcase.cpp:5:7: warning: variable 'array' set but not used
[-Wunused-but-set-variable]

The warning is give only when compiles as C++.

Tested revisions:
r177949 - fail
r173150 - OK
4.6.1 - OK

[Bug c++/50158] [4.7 Regression] invalid 'variable set but not used' warning (boolean used as an index to an array)

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

Zdenek Sojka <zsojka at seznam dot cz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.7 Regression] invalid    |[4.7 Regression] invalid
                   |'variable set but not used' |'variable set but not used'
                   |warning (boolean used as    |warning (boolean used as an
                   |index to an array)          |index to an array)

--- Comment #1 from Zdenek Sojka <zsojka at seznam dot cz> 2011-08-22 19:21:43 UTC ---
> The warning is give only when compiles as C++.

I am sorry for all the typos...

[Bug c++/50158] [4.7 Regression] invalid 'variable set but not used' warning (boolean used as an index to an array)

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.7.0

[Bug c++/50158] [4.7 Regression] invalid 'variable set but not used' warning (boolean used as an index to an array)

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011-08-22
                 CC|                            |jakub at gcc dot gnu.org
     Ever Confirmed|0                           |1

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-22 20:58:20 UTC ---
Caused by http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=176072

[Bug c++/50158] [4.7 Regression] invalid 'variable set but not used' warning (boolean used as an index to an array)

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-23 12:48:15 UTC ---
Created attachment 25082
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25082
gcc47-pr50158.patch

Untested fix.

[Bug c++/50158] [4.7 Regression] invalid 'variable set but not used' warning (boolean used as an index to an array)

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-23 15:53:23 UTC ---
Author: jakub
Date: Tue Aug 23 15:53:18 2011
New Revision: 177992

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=177992
Log:
    PR c++/50158
    * typeck.c (cp_build_modify_expr): Call mark_rvalue_use on rhs
    if it has side-effects and needs to be preevaluated.

    * g++.dg/warn/Wunused-var-16.C: New test.

Added:
    trunk/gcc/testsuite/g++.dg/warn/Wunused-var-16.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/typeck.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/50158] [4.7 Regression] invalid 'variable set but not used' warning (boolean used as an index to an array)

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50158

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-23 15:57:36 UTC ---
Fixed.