[Bug c/27289] New: Gcc produces spurious -Wuninitialized warning compiling gdb

[gcc-bugzilla at gcc dot gnu dot org]

When building gdb with -Werror, the compile fails due to what looks
like a spurious warning from using -Wuninitialized.  I've reduced the
testcase down to a minimal one, hopefully preserving the original
cause of the warning.

Environment:
System: Linux puffer.diveadx.com 2.6.16-1.2069_FC4smp #1 SMP Tue Mar 28
12:47:32 EST 2006 i686 i686 i386 GNU/Linux
Architecture: i686

host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: /src/latest/trunk/src/gcc/configure -v
--prefix=/opt/local/latest/trunk --enable-languages=c,c++
--cache-file=.././config.cache --srcdir=/src/latest/trunk/src/gcc

How-To-Repeat:

/* Run as:

     $ gcc -c -O2 -Wuninitialized bug.c
     bug.c: In function ‘foo’:
     bug.c:19: warning: ‘tmp_obstack.chunk_size’ may be used uninitialized
in this function
*/

struct obstack
{
  long chunk_size;
};

static struct obstack dont_print_statmem_obstack;

void
foo (int dont_print_statmem, int start)
{
  int i;
  struct obstack tmp_obstack;

  if (dont_print_statmem == 0)
    {
      tmp_obstack = dont_print_statmem_obstack;
    }

  for (i = start; i < 7; i++)
    {
    }

  if (dont_print_statmem == 0)
    {
      dont_print_statmem_obstack = tmp_obstack;
    }
}


-- 
           Summary: Gcc produces spurious -Wuninitialized warning compiling
                    gdb
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: fnf at specifix dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=27289