[Bug c/30086] New: Initialize struct to avoid warnings shouldn't be needed

[Bug c/30086] New: Initialize struct to avoid warnings shouldn't be needed

[midoegal at web dot de]

When compiling GDB 6.5.90 on x86 (FC5) GCC gives following warning. So it is
needed to initialize tmp_obstack to avoid this warning. This isn't necessary
and GCC should detect this.

/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c: In function 
'pascal_object_print_value_fields':
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.alloc_failed' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.maybe_empty_object' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.use_extra_arg' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.extra_arg' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.freefun' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.chunkfun' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.alignment_mask' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.temp' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.chunk_limit' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.next_free' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.object_base' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.chunk' may be used uninitialized in this function
/home/user/gdb/6.5.90/gdb-6.5.90/gdb/p-valprint.c:756: warning:
'tmp_obstack.chunk_size' may be used uninitialized in this function
make[2]: *** [p-valprint.o] Error 1
make[2]: Leaving directory `/home/user/gdb/6.5.90/gdb-6.5.90/build_werr/gdb'
make[1]: *** [all-gdb] Error 2
make[1]: Leaving directory `/home/user/gdb/6.5.90/gdb-6.5.90/build_werr'
make: *** [all] Error 2


-- 
           Summary: Initialize struct to avoid warnings shouldn't be needed
           Product: gcc
           Version: 4.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: midoegal at web dot de
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30086

[Bug middle-end/30086] Initialize struct to avoid warnings shouldn't be needed

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-12-06 23:14 -------
Depends how the source looks, it might be actually used uninitialized which
means the code is undefined anyways.
Can you attach the preprocessed source?

I have seen stuff like:

struct a{int t; int t1};

void f(struct a);

void g(void)
{
  struct a b;
  b.t = 1;
  f(b);
}
(maybe a little more complex but you get the idea).
How does GCC know that not all the elements of b are not used.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |middle-end


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30086

[Bug middle-end/30086] Initialize struct to avoid warnings shouldn't be needed

[midoegal at web dot de]

------- Comment #2 from midoegal at web dot de  2006-12-07 09:54 -------
Created an attachment (id=12764)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=12764&action=view)
Source file mentioned in the description


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30086

[Bug middle-end/30086] Initialize struct to avoid warnings shouldn't be needed

[midoegal at web dot de]

------- Comment #3 from midoegal at web dot de  2006-12-07 09:55 -------
I attached the file. Its from GDB 6.5.90 release.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30086

[Bug middle-end/30086] Initialize struct to avoid warnings shouldn't be needed

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2006-12-13 07:31 -------
The problem here is the same as PR 5035 really, just this case has structs and
the other case is for scalars but the problems are the same.

*** This bug has been marked as a duplicate of 5035 ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30086