[Bug c/12391] New: regression: missing warning about assigning to an incomplete type

[Bug c/12391] New: regression: missing warning about assigning to an incomplete type

[levon at movementarian dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391

           Summary: regression: missing warning about assigning to an
                    incomplete  type
           Product: gcc
           Version: 3.4
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: levon at movementarian dot org
                CC: gcc-bugs at gcc dot gnu dot org

Consider:

typedef struct { int a; } b_t;
int foo() { b_t d; struct b_t * c = &d; c->a; }

gcc 3.2 says :

a.c: In function `foo':
a.c:2: warning: initialization from incompatible pointer type
a.c:2: dereferencing pointer to incomplete type

GNU C version 3.4 20030914 (experimental) (i686-pc-linux-gnu) says :

a.c: In function `foo':
a.c:2: error: dereferencing pointer to incomplete type

Note the missing warning on initialisation. This can be moderately confusing
because the latter looks exactly like a "missing header" problem, but in fact
the problem is prepending the "struct" before the typedef name, which is
actually an incomplete type of "struct b_t".

The missing warning makes it obvious that it's not as simple as a missing
header.

[Bug c/12391] [3.4 regression] missing warning about assigning to an incomplete type

[bangerth at dealii dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391


bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|minor                       |normal
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2003-09-24 18:40:24
               date|                            |
            Summary|regression: missing warning |[3.4 regression] missing
                   |about assigning to an       |warning about assigning to
                   |incomplete  type            |an incomplete  type
   Target Milestone|---                         |3.4


------- Additional Comments From bangerth at dealii dot org  2003-09-24 18:40 -------
Right, a mailine regression. What a vicious piece of code. The g++
front end gives this, btw, which I think is a good reason to change
your programming language :-)

g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ -c x.c -W -Wall
x.c: In function `int foo()':
x.c:2: error: using typedef-name `b_t' after `struct'
x.c:2: warning: statement has no effect

[Bug c/12391] [3.4 regression] missing warning about assigning to an incomplete type

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-12-19 05:59 -------
The regresion happened between 20030830 and 20030902.
I want to say it was caused by: <http://gcc.gnu.org/ml/gcc-patches/2003-09/msg00003.html>
Or one of these two:
2003-08-30  Zack Weinberg  <zack@codesourcery.com>

        * c-tree.h: Delete COMPARE_DIFFERENT_TU from enumeration.
        * c-typeck.c (same_translation_unit_p): New function.
        (comptypes): Use it instead of flags parameter to identify
        structure types from different translation units.
        * c-decl.c (duplicate_decls): Always call comptypes with
        COMPTYPE_STRICT flags argument.
        (c_reset_state): Set BLOCK_SUPERCONTEXT of the block formed
        to file_scope_decl.

2003-08-30  Zack Weinberg  <zack@codesourcery.com>

        * c-tree.h (C_TYPE_INCOMPLETE_VARS): New macro.
        * c-decl.c (struct c_scope): Remove "incomplete" field.
        (pushdecl): Attach variables with incomplete types to
        the TYPE_MAIN_VARIANT of the incomplete type in question.
        (finish_struct): Look at C_TYPE_INCOMPLETE_VARS for variables
        to complete, not at current_scope->incomplete.  All such
        variables do need completion.

These are the only patches which touched the c front-end which could cause this problem.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391

[Bug c/12391] [3.4/3.5 regression] missing warning about assigning to an incomplete type

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-02-28 02:35 -------
This is a very minor issue: postponed until GCC 3.4.1.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|3.4.0                       |3.4.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391

[Bug c/12391] [3.4/3.5 regression] missing warning about assigning to an incomplete type

[zack at gcc dot gnu dot org]

------- Additional Comments From zack at gcc dot gnu dot org  2004-03-16 20:57 -------
Fixed by the c-decl.c rewrite:
http://gcc.gnu.org/ml/gcc-patches/2004-03/msg01280.html

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391

[Bug c/12391] [3.4 regression] missing warning about assigning to an incomplete type

[zack at gcc dot gnu dot org]

------- Additional Comments From zack at gcc dot gnu dot org  2004-03-23 23:52 -------
fixed in 3.5

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|3.3                         |3.3 3.5.0
            Summary|[3.4/3.5 regression] missing|[3.4 regression] missing
                   |warning about assigning to  |warning about assigning to
                   |an incomplete  type         |an incomplete  type


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391

[Bug c/12391] [3.4 regression] missing warning about assigning to an incomplete type

[zack at gcc dot gnu dot org]

------- Additional Comments From zack at gcc dot gnu dot org  2004-06-01 04:25 -------
Suspending bugs which could be fixed by backporting the c-decl.c rewrite to 3.4.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |SUSPENDED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391

[Bug c/12391] [3.4 regression] missing warning about assigning to an incomplete type

[mmitchel at gcc dot gnu dot org]

------- Additional Comments From mmitchel at gcc dot gnu dot org  2004-06-09 19:20 -------
Fixed in 3.5, won't be fixed in 3.4.x.

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12391