diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 031e46d1457..78b43a31a9a 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1168,6 +1168,11 @@ typedef struct gfc_actual_arglist
   gfc_param_spec_type spec_type;
 
   struct gfc_expr *expr;
+
+  /*  The dummy arg this actual arg is associated with, if the interface
+      is explicit.  NULL otherwise.  */
+  gfc_dummy_arg *associated_dummy;
+
   struct gfc_actual_arglist *next;
 }
 gfc_actual_arglist;
@@ -2174,7 +2179,6 @@ struct gfc_intrinsic_arg : public gfc_dummy_arg
   gfc_typespec ts;
   unsigned optional:1, value:1;
   ENUM_BITFIELD (sym_intent) intent:2;
-  gfc_actual_arglist *actual;
 
   struct gfc_intrinsic_arg *next;
 };
diff --git a/gcc/fortran/interface.c b/gcc/fortran/interface.c
index 9e3e8aa9da9..b763f87e8bd 100644
--- a/gcc/fortran/interface.c
+++ b/gcc/fortran/interface.c
@@ -3131,6 +3131,8 @@ gfc_compare_actual_formal (gfc_actual_arglist **ap, gfc_formal_arglist *formal,
 			   "call at %L", where);
 	  return false;
 	}
+      else
+	a->associated_dummy = f;
 
       if (a->expr == NULL)
 	{
@@ -3546,9 +3548,12 @@ gfc_compare_actual_formal (gfc_actual_arglist **ap, gfc_formal_arglist *formal,
   /* The argument lists are compatible.  We now relink a new actual
      argument list with null arguments in the right places.  The head
      of the list remains the head.  */
-  for (i = 0; i < n; i++)
+  for (f = formal, i = 0; f; f = f->next, i++)
     if (new_arg[i] == NULL)
-      new_arg[i] = gfc_get_actual_arglist ();
+      {
+	new_arg[i] = gfc_get_actual_arglist ();
+	new_arg[i]->associated_dummy = f;
+      }
 
   if (na != 0)
     {
diff --git a/gcc/fortran/intrinsic.c b/gcc/fortran/intrinsic.c
index 2b7b72f03e2..ef5da389434 100644
--- a/gcc/fortran/intrinsic.c
+++ b/gcc/fortran/intrinsic.c
@@ -4290,8 +4290,14 @@ sort_actual (const char *name, gfc_actual_arglist **ap,
   remove_nullargs (ap);
   actual = *ap;
 
+  auto_vec<gfc_intrinsic_arg *> dummy_args;
+  auto_vec<gfc_actual_arglist *> ordered_actual_args;
+
   for (f = formal; f; f = f->next)
-    f->actual = NULL;
+    dummy_args.safe_push (f);
+
+  ordered_actual_args.safe_grow_cleared (dummy_args.length (),
+					 /* exact = */true);
 
   f = formal;
   a = actual;
@@ -4343,7 +4349,7 @@ sort_actual (const char *name, gfc_actual_arglist **ap,
 	}
     }
 
-  for (;;)
+  for (int i = 0;; i++)
     {		/* Put the nonkeyword arguments in a 1:1 correspondence */
       if (f == NULL)
 	break;
@@ -4353,7 +4359,7 @@ sort_actual (const char *name, gfc_actual_arglist **ap,
       if (a->name != NULL)
 	goto keywords;
 
-      f->actual = a;
+      ordered_actual_args[i] = a;
 
       f = f->next;
       a = a->next;
@@ -4371,7 +4377,8 @@ keywords:
      to be keyword arguments.  */
   for (; a; a = a->next)
     {
-      for (f = formal; f; f = f->next)
+      int idx;
+      FOR_EACH_VEC_ELT (dummy_args, idx, f)
 	if (strcmp (a->name, f->name) == 0)
 	  break;
 
@@ -4386,21 +4393,21 @@ keywords:
 	  return false;
 	}
 
-      if (f->actual != NULL)
+      if (ordered_actual_args[idx] != NULL)
 	{
 	  gfc_error ("Argument %qs appears twice in call to %qs at %L",
 		     f->name, name, where);
 	  return false;
 	}
-
-      f->actual = a;
+      ordered_actual_args[idx] = a;
     }
 
 optional:
   /* At this point, all unmatched formal args must be optional.  */
-  for (f = formal; f; f = f->next)
+  int idx;
+  FOR_EACH_VEC_ELT (dummy_args, idx, f)
     {
-      if (f->actual == NULL && f->optional == 0)
+      if (ordered_actual_args[idx] == NULL && f->optional == 0)
 	{
 	  gfc_error ("Missing actual argument %qs in call to %qs at %L",
 		     f->name, name, where);
@@ -4413,9 +4420,9 @@ do_sort:
      together in a way that corresponds with the formal list.  */
   actual = NULL;
 
-  for (f = formal; f; f = f->next)
+  FOR_EACH_VEC_ELT (dummy_args, idx, f)
     {
-      a = f->actual;
+      a = ordered_actual_args[idx];
       if (a && a->label != NULL && f->ts.type)
 	{
 	  gfc_error ("ALTERNATE RETURN not permitted at %L", where);
@@ -4428,6 +4435,8 @@ do_sort:
 	  a->missing_arg_type = f->ts.type;
 	}
 
+      a->associated_dummy = f;
+
       if (actual == NULL)
 	*ap = a;
       else