[fortran] Fix PR 38536

Submitted by Tobias Burnus on Jan. 22, 2011, 6:03 p.m.

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Message ID 4D3B1C08.2050709@net-b.de
State New
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Commit Message

Tobias Burnus Jan. 22, 2011, 6:03 p.m.
On 01/15/2011 02:45 PM, Thomas Koenig wrote:
>>> here is an update of the patch.  This one just warns about array
>>> sections if they are followed by component references.

s/warns/prints an error/

> Revision 169130 ├╝bertragen.

How about the following patch on top of it? I think the crucial part 
(for F2008 at least) is rather the contiguity. The patch looks longer 
than it is due to white space changes.

Tobias

Comments

Thomas Koenig Jan. 23, 2011, 11:27 a.m.
Hi Tobias,

> On 01/15/2011 02:45 PM, Thomas Koenig wrote:
>>>> here is an update of the patch.  This one just warns about array
>>>> sections if they are followed by component references.
> 
> s/warns/prints an error/
> 
>> Revision 169130 ├╝bertragen.
> 
> How about the following patch on top of it? I think the crucial part
> (for F2008 at least) is rather the contiguity. The patch looks longer
> than it is due to white space changes.

Shouldn't the test on gfc_is_simply_contiguous be reversed?  The test
case in c_loc_tests_16.f90 would then have to be changed.

	Thomas
Thomas Koenig Jan. 23, 2011, 1:28 p.m.
Hi Tobias,

>> > On 01/15/2011 02:45 PM, Thomas Koenig wrote:
>>>>> >>>> here is an update of the patch.  This one just warns about array
>>>>> >>>> sections if they are followed by component references.
>> > 
>> > s/warns/prints an error/
>> > 
>>> >> Revision 169130 ├╝bertragen.
>> > 
>> > How about the following patch on top of it? I think the crucial part
>> > (for F2008 at least) is rather the contiguity. The patch looks longer
>> > than it is due to white space changes.
> Shouldn't the test on gfc_is_simply_contiguous be reversed?  The test
> case in c_loc_tests_16.f90 would then have to be changed.

I applied your patch with the test reversed and tested it with the
following source:

ig25@linux-fd1f:~/Krempel/Ref-c> cat cloc.f90
! { dg-do compile }
! PR 38536 - array sections as arguments to c_loc are illegal.
program main
  use iso_c_binding
  implicit none
  interface
     subroutine fun(arg) BIND(C)
       use iso_c_binding
       type(c_ptr) :: arg
     end subroutine fun
  end interface

  integer(c_int), target :: n(3)

  type(C_PTR) :: p

  n(1) = 3
  n(2) = 5
  n(3) = 7
  p = c_loc(n)
  call fun(p)
  p = c_loc(n(2:3))  ! { dg-warning "Array section" }
  call fun(p)
  print *,n
end program main
ig25@linux-fd1f:~/Krempel/Ref-c> cat fun.c
#include <stdio.h>

void fun(void *);

void fun(void *p)
{
  int *pp;
  pp = p;
  printf("%p %d %d\n",p, pp[0], pp[1]);
}
ig25@linux-fd1f:~/Krempel/Ref-c> gfortran cloc.f90 fun.c
ig25@linux-fd1f:~/Krempel/Ref-c> ./a.out
0x7fff4e19b508 1310307600 32767
0x7fff4e19b508 1310307604 32767
           3           5           7

Either my test program is wrong (which is entirely possible because I
don't use ISO C binding myself, much), or there are at least two
problems with using c_loc like this - the first version should have
worked in any case.

	Thomas
Tobias Burnus Jan. 23, 2011, 2:13 p.m.
Dear Thomas,

Thomas Koenig wrote:
> I applied your patch with the test reversed and tested it with the
> following source:
>
> [...]
>    interface
>       subroutine fun(arg) BIND(C)
>         use iso_c_binding
>         type(c_ptr) :: arg
[...]
> void fun(void *);

The interface does not really match. On the Fortran side, you have "void 
**" on the C side you only have "void *". Try:

        type(c_ptr), VALUE :: arg


The result is then:

0x7fffc66564c0 3 5
0x7fffc66564c4 5 7
            3           5           7

C Binding is described at 
http://gcc.gnu.org/onlinedocs/gfortran/Mixed_002dLanguage-Programming.html 
-- and the pointer handling in particular at 
http://gcc.gnu.org/onlinedocs/gfortran/Working-with-Pointers.html

Side remark: If it were not for a C_LOC example, I had used "int *" on 
the C side and "integer(c_int) :: arg(*)" on the Fortran side.

Tobias
Thomas Koenig Jan. 23, 2011, 2:52 p.m.
Hi Tobias,

> Dear Thomas,
> 
> Thomas Koenig wrote:
>> I applied your patch with the test reversed and tested it with the
>> following source:
>>
>> [...]
>>    interface
>>       subroutine fun(arg) BIND(C)
>>         use iso_c_binding
>>         type(c_ptr) :: arg
> [...]
>> void fun(void *);
> 
> The interface does not really match. On the Fortran side, you have "void
> **" on the C side you only have "void *".

You learn something new every day...

Your patch is OK with the test for gfc_is_simply_contiguous reversed,
regression-testing and an appropriate test case and change to
c_loc_tests_16.f90.

	Thomas

Patch hide | download patch | download mbox

diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index 9f0d675..f458cbe 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -2700,7 +2700,6 @@  gfc_iso_c_func_interface (gfc_symbol *sym, gfc_actual_arglist *args,
       else if (sym->intmod_sym_id == ISOCBINDING_LOC)
         {
 	  gfc_ref *ref;
-	  bool seen_section;
 
           /* Make sure we have either the target or pointer attribute.  */
 	  if (!arg_attr.target && !arg_attr.pointer)
@@ -2722,35 +2721,29 @@  gfc_iso_c_func_interface (gfc_symbol *sym, gfc_actual_arglist *args,
 
 	  /* Follow references to make sure there are no array
 	     sections.  */
-	  seen_section = false;
 
 	  for (ref=args->expr->ref; ref; ref = ref->next)
 	    {
 	      if (ref->type == REF_ARRAY)
-		{
-		  if (ref->u.ar.type == AR_SECTION)
-		    seen_section = true;
-
-		  if (ref->u.ar.type != AR_ELEMENT)
-		    {
-		      gfc_ref *r;
-		      for (r = ref->next; r; r=r->next)
-			if (r->type == REF_COMPONENT)
-			  {
+		if (ref->u.ar.type != AR_ELEMENT)
+		  {
+		    gfc_ref *r;
+		    for (r = ref->next; r; r=r->next)
+		      if (r->type == REF_COMPONENT)
+			{
 			    gfc_error_now ("Array section not permitted"
 					   " in '%s' call at %L", name,
 					   &(args->expr->where));
 			    retval = FAILURE;
 			    break;
-			  }
-		    }
-		}
+			}
+		  }
 	    }
 
-	  if (seen_section && retval == SUCCESS)
-	    gfc_warning ("Array section in '%s' call at %L", name,
+	  if (retval == SUCCESS && gfc_is_simply_contiguous (args->expr, false))
+	    gfc_warning ("Array might be not contiguous in '%s' call at %L", name,
 			 &(args->expr->where));
-			 
+
           /* See if we have interoperable type and type param.  */
           if (verify_c_interop (arg_ts) == SUCCESS
               || gfc_check_any_c_kind (arg_ts) == SUCCESS)