Here the initializer for x is represented as an empty CONSTRUCTOR due to
its empty element type. So during constexpr evaluation of the ARRAY_REF
x[0], we end up trying to value initialize the omitted element at index 0,
which fails because the element type is not default constructible.
This patch makes cxx_eval_array_reference specifically handle the case
where the element type is an empty type.
PR c++/101194
gcc/cp/ChangeLog:
* constexpr.c (cxx_eval_array_reference): When the element type
is an empty type and the corresponding element is omitted, just
return an empty CONSTRUCTOR instead of attempting value
initialization.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-empty16.C: New test.
directly for non-aggregates to avoid creating a garbage CONSTRUCTOR. */
tree val;
constexpr_ctx new_ctx;
- if (CP_AGGREGATE_TYPE_P (elem_type))
+ if (is_really_empty_class (elem_type, /*ignore_vptr*/false))
+ return build_constructor (elem_type, NULL);
+ else if (CP_AGGREGATE_TYPE_P (elem_type))
{
tree empty_ctor = build_constructor (init_list_type_node, NULL);
val = digest_init (elem_type, empty_ctor, tf_warning_or_error);
--- /dev/null
+// PR c++/101194
+// { dg-do compile { target c++11 } }
+
+struct nodefault {
+ constexpr nodefault(int) { }
+};
+
+constexpr nodefault x[1] = { nodefault{0} };
+
+constexpr nodefault y = x[0];