re PR fortran/34558 (ICE with same TYPE in both program and interface)

2007-12-31  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/34558
	* interface.c (gfc_compare_types): Prevent linked lists from
	putting this function into an endless recursive loop.

2007-12-31  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/34558
	* gfortran.dg/linked_list_1.f90: New test.

From-SVN: r131239

gcc/fortran/interface.c

@@ -407,17 +407,19 @@ gfc_compare_derived_types (gfc_symbol *derived1, gfc_symbol *derived2)
       if (dt1->dimension && gfc_compare_array_spec (dt1->as, dt2->as) == 0)
 	return 0;
 
-      /* Make sure that link lists do not put this function in an
-	 endless loop!  */
+      /* Make sure that link lists do not put this function into an 
+	 endless recursive loop!  */
       if (!(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.derived)
 	    && !(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.derived)
 	    && gfc_compare_types (&dt1->ts, &dt2->ts) == 0)
 	return 0;
 
-      else if (dt1->ts.type != BT_DERIVED
-		 || derived1 != dt1->ts.derived
-		 || dt2->ts.type != BT_DERIVED
-		 || derived2 != dt2->ts.derived)
+      else if ((dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.derived)
+		&& !(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.derived))
+	return 0;
+
+      else if (!(dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.derived)
+		&& (dt1->ts.type == BT_DERIVED && derived1 == dt1->ts.derived))
 	return 0;
 
       dt1 = dt1->next;