c++: tweak PR103337 fix

Patrick suggested a way to implement the designated-init handling without
(temporarily) modifying the CONSTRUCTOR being reshaped.

	PR c++/103337

gcc/cp/ChangeLog:

	* decl.cc (reshape_single_init): New.
	(reshape_init_class): Use it.

diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 34d9dad..efef1b7 100644 (file)
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -6543,6 +6543,21 @@ reshape_init_vector (tree type, reshape_iter *d, tsubst_flags_t complain)
                               NULL_TREE, complain);
 }
 
+/* Subroutine of reshape_init*: We're initializing an element with TYPE from
+   INIT, in isolation from any designator or other initializers.  */
+
+static tree
+reshape_single_init (tree type, tree init, tsubst_flags_t complain)
+{
+  /* We could also implement this by wrapping init in a new CONSTRUCTOR and
+     calling reshape_init, but this way can just live on the stack.  */
+  constructor_elt elt = { /*index=*/NULL_TREE, init };
+  reshape_iter iter = { &elt, &elt + 1 };
+  return reshape_init_r (type, &iter,
+                        /*first_initializer_p=*/NULL_TREE,
+                        complain);
+}
+
 /* Subroutine of reshape_init_r, processes the initializers for classes
    or union. Parameters are the same of reshape_init_r.  */
 
@@ -6690,24 +6705,19 @@ reshape_init_class (tree type, reshape_iter *d, bool first_initializer_p,
 
       if (direct_desig)
        {
-         /* The designated field F is initialized from this one element:
-            Temporarily clear the designator so a recursive reshape_init_class
-            doesn't try to find it again in F, and adjust d->end so we don't
-            try to use the next initializer to initialize another member of F.
+         /* The designated field F is initialized from this one element.
 
-            Note that we don't want these changes if we found the designator
-            inside an anon aggr above; we leave them alone to implement:
+            Note that we don't want to do this if we found the designator
+            inside an anon aggr above; we use the normal code to implement:
 
             "If the element is an anonymous union member and the initializer
             list is a brace-enclosed designated- initializer-list, the element
             is initialized by the designated-initializer-list { D }, where D
             is the designated- initializer-clause naming a member of the
             anonymous union member."  */
-         auto end_ = make_temp_override (d->end, d->cur + 1);
-         auto idx_ = make_temp_override (d->cur->index, NULL_TREE);
-         field_init = reshape_init_r (TREE_TYPE (field), d,
-                                      /*first_initializer_p=*/NULL_TREE,
-                                      complain);
+         field_init = reshape_single_init (TREE_TYPE (field),
+                                           d->cur->value, complain);
+         d->cur++;
        }
       else
        field_init = reshape_init_r (TREE_TYPE (field), d,