[Bug c/25801] New: bad diagnostic for increment/decrement of pointer to incomplete array

[Bug c/25801] New: bad diagnostic for increment/decrement of pointer to incomplete array

[jsm28 at gcc dot gnu dot org]

extern int (*a)[];
void g(void) { a++; }

yields the diagnostics

t2.c: In function 'g':
t2.c:2: error: increment of pointer to unknown structure
t2.c:2: error: arithmetic on pointer to an incomplete type

This isn't a pointer to a structure, it's one to an array; and after giving the
first diagnostic, it's useless to go on and give the second as well.


-- 
           Summary: bad diagnostic for increment/decrement of pointer to
                    incomplete array
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: jsm28 at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25801

[Bug c/25801] bad diagnostic for increment/decrement of pointer to incomplete array

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2006-01-16 01:25 -------
The problem with the first error message is obvious where it goes wrong (in
c-typeck.c):
            if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (result_type)))
              {
                if (code == PREINCREMENT_EXPR || code == POSTINCREMENT_EXPR)
                  error ("increment of pointer to unknown structure");
                else
                  error ("decrement of pointer to unknown structure");

The second one comes from calling c_size_in_bytes.  It seems like we can remove
the error call from c_size_in_bytes as the other place were we call it, we
check for a imcomplete type right before calling it.
Oh and the second error message also happens with the struct case too.

Both are these problems are not a regression as far as I can tell as both wrong
error messages are in 2.95.3.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |diagnostic
      Known to fail|                            |2.95.3 3.3.1 3.0.4 3.4.0
                   |                            |4.0.0 4.1.0 4.2.0
   Last reconfirmed|0000-00-00 00:00:00         |2006-01-16 01:25:15
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25801

[Bug c/25801] bad diagnostic for increment/decrement of pointer to incomplete array

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25801

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

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

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed.

[Bug c/25801] bad diagnostic for increment/decrement of pointer to incomplete array

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25801

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Author: mpolacek
Date: Fri May  2 18:13:43 2014
New Revision: 210013

URL: http://gcc.gnu.org/viewcvs?rev=210013&root=gcc&view=rev
Log:
    PR c/25801
    * c-typeck.c (c_size_in_bytes): Update comment.  Don't call error.
    Return size_one_node when the type is not complete.
    (pointer_diff): Remove comment.
    (build_unary_op): Improve error messages.

    * gcc.dg/pr25801.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr25801.c
Modified:
    trunk/gcc/c/ChangeLog
    trunk/gcc/c/c-typeck.c
    trunk/gcc/testsuite/ChangeLog

[Bug c/25801] bad diagnostic for increment/decrement of pointer to incomplete array

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25801

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
                 CC|                            |mpolacek at gcc dot gnu.org
           Assignee|unassigned at gcc dot gnu.org      |mpolacek at gcc dot gnu.org

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I'm testing a patch.