[Patch, fortran] Fix PR 51338 - ICE with front-end optimization and assumed character lengths

[Tobias Burnus]

Thomas Koenig wrote:
> Regression-tested. OK for trunk?
>
> 2011-11-29  Thomas Koenig <tkoenig@gcc.gnu.org>
>
>         PR fortran/51338
>         * dependency.c (are_identical_variables):  Handle case where
>         end fields of substring references are NULL.
>
> 2011-11-29  Thomas Koenig <tkoenig@gcc.gnu.org>
>
>         PR fortran/51338
>         * gfortran.dg/assumed_charlen_substring_1.f90:  New test.
> +	  /* This can only happen for assumed-length character arguments.
> +	     If both are NULL, the end length compares equal, because we
> +	     are looking at the same variable.  */
> +	  if (r1->u.ss.end == NULL&&  r2->u.ss.end == NULL)
> +	    break;

Well, it can also happen for deferred-length arguments; how about:

+	  /* If both are NULL, the end length compares equal, because we
+	     are looking at the same variable. This can only happen for
+	     assumed- or deferred-length character arguments.  */


OK with that change.

Thanks for the patch and sorry for the slow review.

Tobias

PS: Patches which still need to be reviewed:
- http://gcc.gnu.org/ml/fortran/2011-11/msg00250.html - no 
-fcheck=bounds for character(LEN=:) to avoid ICE
- http://gcc.gnu.org/ml/fortran/2011-11/msg00253.html - (Re)enable 
warning if a function result variable is not set [4.4-4.7 diagnostics 
regression]
- http://gcc.gnu.org/ml/fortran/2011-12/msg00018.html - fix ASSOCIATE 
with extended types