Re: [Patch, Fortran] Cleanup of gfc_extend_expr

[Janus Weil <janus at gcc dot gnu dot org>]

> At least add a comment about the re-use (abuse?) of the
> enum.

Updated patch attached, which adds a short comment on the usage of 'match'.


> This should reduce confusion months from when
> someone wonders why gfc_extend_expr returns a "match"
> for a non-matching function.

Well, I think my approach is not as far-fetched as you seem to imply:
There are already a good number of procedures which use the 'match'
enum, although they're not related to matching at all. Listing only
those that occur in gfortran.h (I'm sure there are more):

 * match gfc_mod_pointee_as (gfc_array_spec *);
 * match gfc_intrinsic_func_interface (gfc_expr *, int);
 * match gfc_intrinsic_sub_interface (gfc_code *, int);
 * match gfc_iso_c_sub_interface(gfc_code *, gfc_symbol *);

The reason for this is of course that the YES/NO/ERROR triple is not
only useful in matching, but also in many other situations.

Cheers,
Janus

Index: gcc/fortran/interface.c
===================================================================
--- gcc/fortran/interface.c	(revision 180820)
+++ gcc/fortran/interface.c	(working copy)
@@ -3220,12 +3220,11 @@ build_compcall_for_operator (gfc_expr* e, gfc_actu
    with the operator.  This subroutine builds an actual argument list
    corresponding to the operands, then searches for a compatible
    interface.  If one is found, the expression node is replaced with
-   the appropriate function call.
-   real_error is an additional output argument that specifies if FAILURE
-   is because of some real error and not because no match was found.  */
+   the appropriate function call. We use the 'match' enum to specify
+   whether a replacement has been made or not, or if an error occurred.  */
 
-gfc_try
-gfc_extend_expr (gfc_expr *e, bool *real_error)
+match
+gfc_extend_expr (gfc_expr *e)
 {
   gfc_actual_arglist *actual;
   gfc_symbol *sym;
@@ -3239,7 +3238,6 @@ build_compcall_for_operator (gfc_expr* e, gfc_actu
   actual = gfc_get_actual_arglist ();
   actual->expr = e->value.op.op1;
 
-  *real_error = false;
   gname = NULL;
 
   if (e->value.op.op2 != NULL)
@@ -3343,16 +3341,16 @@ build_compcall_for_operator (gfc_expr* e, gfc_actu
 
 	  result = gfc_resolve_expr (e);
 	  if (result == FAILURE)
-	    *real_error = true;
+	    return MATCH_ERROR;
 
-	  return result;
+	  return MATCH_YES;
 	}
 
       /* Don't use gfc_free_actual_arglist().  */
       free (actual->next);
       free (actual);
 
-      return FAILURE;
+      return MATCH_NO;
     }
 
   /* Change the expression node to a function call.  */
@@ -3365,12 +3363,9 @@ build_compcall_for_operator (gfc_expr* e, gfc_actu
   e->user_operator = 1;
 
   if (gfc_resolve_expr (e) == FAILURE)
-    {
-      *real_error = true;
-      return FAILURE;
-    }
+    return MATCH_ERROR;
 
-  return SUCCESS;
+  return MATCH_YES;
 }
 
 
Index: gcc/fortran/gfortran.h
===================================================================
--- gcc/fortran/gfortran.h	(revision 180820)
+++ gcc/fortran/gfortran.h	(working copy)
@@ -2831,7 +2831,7 @@ void gfc_procedure_use (gfc_symbol *, gfc_actual_a
 void gfc_ppc_use (gfc_component *, gfc_actual_arglist **, locus *);
 gfc_symbol *gfc_search_interface (gfc_interface *, int,
 				  gfc_actual_arglist **);
-gfc_try gfc_extend_expr (gfc_expr *, bool *);
+match gfc_extend_expr (gfc_expr *);
 void gfc_free_formal_arglist (gfc_formal_arglist *);
 gfc_try gfc_extend_assign (gfc_code *, gfc_namespace *);
 gfc_try gfc_add_interface (gfc_symbol *);
Index: gcc/fortran/resolve.c
===================================================================
--- gcc/fortran/resolve.c	(revision 180820)
+++ gcc/fortran/resolve.c	(working copy)
@@ -4034,11 +4034,10 @@ resolve_operator (gfc_expr *e)
 bad_op:
 
   {
-    bool real_error;
-    if (gfc_extend_expr (e, &real_error) == SUCCESS)
+    match m = gfc_extend_expr (e);
+    if (m == MATCH_YES)
       return SUCCESS;
-
-    if (real_error)
+    if (m == MATCH_ERROR)
       return FAILURE;
   }