[Bug c/50179] New: wrong "set but not used" warning

[Bug c/50179] New: wrong "set but not used" warning

[aldot at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50179

             Bug #: 50179
           Summary: wrong "set but not used" warning
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: aldot@gcc.gnu.org


To me it looks like the warning below is not correct. The variable is in fact
used.

$ gcc-4.6 -c -o bug.o bug.c -Wall
bug.c: In function ‘huh’:
bug.c:5:15: warning: variable ‘b__’ set but not used
[-Wunused-but-set-variable]
$ cat bug.c
#include <stdio.h>
void huh(void) {
    printf("%s", (__extension__(
        {
        static char b__[129];
        b__[0] = 1;
        b__[1] = 2;
        b__[2] = 0;
        b__;
        }))
    );
}

[Bug c/50179] wrong "set but not used" warning

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50179

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2011-08-25
         AssignedTo|unassigned at gcc dot       |jakub at gcc dot gnu.org
                   |gnu.org                     |
     Ever Confirmed|0                           |1

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-25 10:25:17 UTC ---
Created attachment 25098
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25098
gcc47-pr50179.patch

Untested fix.

[Bug c/50179] [4.6/4.7 Regression] wrong "set but not used" warning

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50179

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.6.2
            Summary|wrong "set but not used"    |[4.6/4.7 Regression] wrong
                   |warning                     |"set but not used" warning

[Bug c/50179] [4.6/4.7 Regression] wrong "set but not used" warning

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50179

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-26 14:37:25 UTC ---
Author: jakub
Date: Fri Aug 26 14:37:22 2011
New Revision: 178110

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178110
Log:
    PR c/50179
    * c-typeck.c (c_process_expr_stmt): Skip over nops and
    call mark_exp_read even if exprv is ADDR_EXPR.

    * c-c++-common/Wunused-var-14.c: New test.

Added:
    trunk/gcc/testsuite/c-c++-common/Wunused-var-14.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-typeck.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/50179] [4.6/4.7 Regression] wrong "set but not used" warning

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50179

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-26 14:48:13 UTC ---
Author: jakub
Date: Fri Aug 26 14:48:10 2011
New Revision: 178112

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=178112
Log:
    PR c/50179
    * c-typeck.c (c_process_expr_stmt): Skip over nops and
    call mark_exp_read even if exprv is ADDR_EXPR.

    * c-c++-common/Wunused-var-14.c: New test.

Added:
    branches/gcc-4_6-branch/gcc/testsuite/c-c++-common/Wunused-var-14.c
Modified:
    branches/gcc-4_6-branch/gcc/ChangeLog
    branches/gcc-4_6-branch/gcc/c-typeck.c
    branches/gcc-4_6-branch/gcc/testsuite/ChangeLog

[Bug c/50179] [4.6/4.7 Regression] wrong "set but not used" warning

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50179

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

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> 2011-08-26 16:26:52 UTC ---
Fixed.