===================================================================
@@ -6932,6 +6932,7 @@ components_to_record (tree gnu_record_ty
tree gnu_rep_list = NULL_TREE;
tree gnu_var_list = NULL_TREE;
tree gnu_self_list = NULL_TREE;
+ tree gnu_zero_list = NULL_TREE;
/* For each component referenced in a component declaration create a GCC
field and add it to the list, skipping pragmas in the GNAT list. */
@@ -7262,6 +7263,10 @@ components_to_record (tree gnu_record_ty
to do this in a separate pass since we want to handle the discriminants
but can't play with them until we've used them in debugging data above.
+ Similarly, pull out the fields with zero size and no rep clause, as they
+ would otherwise modify the layout and thus very likely run afoul of the
+ Ada semantics, which are different from those of C here.
+
??? If we reorder them, debugging information will be wrong but there is
nothing that can be done about this at the moment. */
gnu_last = NULL_TREE;
@@ -7300,6 +7305,19 @@ components_to_record (tree gnu_record_ty
continue;
}
+ if (DECL_SIZE (gnu_field) && integer_zerop (DECL_SIZE (gnu_field)))
+ {
+ DECL_FIELD_OFFSET (gnu_field) = size_zero_node;
+ SET_DECL_OFFSET_ALIGN (gnu_field, BIGGEST_ALIGNMENT);
+ DECL_FIELD_BIT_OFFSET (gnu_field) = bitsize_zero_node;
+ if (field_is_aliased (gnu_field))
+ TYPE_ALIGN (gnu_record_type)
+ = MAX (TYPE_ALIGN (gnu_record_type),
+ TYPE_ALIGN (TREE_TYPE (gnu_field)));
+ MOVE_FROM_FIELD_LIST_TO (gnu_zero_list);
+ continue;
+ }
+
gnu_last = gnu_field;
}
@@ -7392,6 +7410,11 @@ components_to_record (tree gnu_record_ty
finish_record_type (gnu_record_type, gnu_field_list, layout_with_rep ? 1 : 0,
debug_info && !maybe_unused);
+ /* Chain the fields with zero size at the beginning of the field list. */
+ if (gnu_zero_list)
+ TYPE_FIELDS (gnu_record_type)
+ = chainon (gnu_zero_list, TYPE_FIELDS (gnu_record_type));
+
return (gnu_rep_list && !p_gnu_rep_list) || variants_have_rep;
}