[patch, fortran] Fix PR 57048

[Steve Kargl]

On Mon, Jan 28, 2019 at 08:49:52PM +0100, Thomas König wrote:
> 
> the attached patch fixes a long-time regression where a c_funptr from a
> module could not be found.
> 
> The solution is a bit of a hack, but so is our whole implementation of
> the C interop stuff.
> 
> Regression-tested. OK for trunk?
> 
> Regards
> 
> 	Thomas
> 
> 2019-01-28  Thomas Koenig  <tkoenig@gcc.gnu.org>
> 
> 	PR fortran/57048
> 	* interface.c (gfc_compare_types): If a derived type and an
> 	integer both have a derived type, and they are identical,
> 	this is a C binding type and compares equal.

I don't understand this sentence.  How can an INTEGER have a
derived type?

> 
> 2019-01-28  Thomas Koenig  <tkoenig@gcc.gnu.org>
> 
> 	PR fortran/57048
> 	* gfortran.dg/c_funptr_1.f90: New file.
> 	* gfortran.dg/c_funptr_1_mod.f90: New file.

> Index: interface.c
> ===================================================================
> --- interface.c	(Revision 268104)
> +++ interface.c	(Arbeitskopie)
> @@ -692,6 +692,15 @@ gfc_compare_types (gfc_typespec *ts1, gfc_typespec
>    if (ts1->type == BT_VOID || ts2->type == BT_VOID)
>      return true;
>  
> +  /* Special case for our C interop types.  There should be a better
> +     way of doing this...  */
> +
> +  if (((ts1->type == BT_INTEGER && ts2->type == BT_DERIVED)
> +       || (ts1->type == BT_DERIVED && ts2->type == BT_INTEGER))
> +      && ts1->u.derived && ts2->u.derived
> +      && ts1->u.derived == ts2->u.derived)
> +    return true;

If the above is a test for ISO C binding, shouldn't the test
also check (ts1->is_c_interop || ts1->is_iso_c) and similar
for ts2?

-- 
Steve