};
#endif
+// Tag used to default initialize one or both of the pair's elements.
+struct __default_init_tag {};
+
template <class _Tp, int _Idx,
bool _CanBeEmptyBase =
is_empty<_Tp>::value && !__libcpp_is_final<_Tp>::value>
#ifndef _LIBCPP_CXX03_LANG
_LIBCPP_INLINE_VISIBILITY constexpr __compressed_pair_elem() : __value_() {}
+ _LIBCPP_INLINE_VISIBILITY constexpr
+ __compressed_pair_elem(__default_init_tag) {}
template <class _Up, class = typename enable_if<
!is_same<__compressed_pair_elem, typename decay<_Up>::type>::value
#else
_LIBCPP_INLINE_VISIBILITY __compressed_pair_elem() : __value_() {}
_LIBCPP_INLINE_VISIBILITY
+ __compressed_pair_elem(__default_init_tag) {}
+ _LIBCPP_INLINE_VISIBILITY
__compressed_pair_elem(_ParamT __p) : __value_(std::forward<_ParamT>(__p)) {}
#endif
--- /dev/null
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <assert.h>
+#include <memory>
+
+#include "test_macros.h"
+
+typedef std::__compressed_pair<int, unsigned> IntPair;
+
+void test_constructor() {
+ IntPair value;
+ assert(value.first() == 0);
+ assert(value.second() == 0);
+
+ value.first() = 1;
+ value.second() = 2;
+ new (&value) IntPair;
+ assert(value.first() == 0);
+ assert(value.second() == 0);
+}
+
+void test_constructor_default_init() {
+ IntPair value;
+ value.first() = 1;
+ value.second() = 2;
+
+ new (&value) IntPair(std::__default_init_tag(), 3);
+ assert(value.first() == 1);
+ assert(value.second() == 3);
+
+ new (&value) IntPair(4, std::__default_init_tag());
+ assert(value.first() == 4);
+ assert(value.second() == 3);
+
+ new (&value) IntPair(std::__default_init_tag(), std::__default_init_tag());
+ assert(value.first() == 4);
+ assert(value.second() == 3);
+}
+
+int main(int, char**)
+{
+ test_constructor();
+ test_constructor_default_init();
+ return 0;
+}