1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___TYPE_TRAITS_ADD_LVALUE_REFERENCE_H
10#define _LIBCPP___TYPE_TRAITS_ADD_LVALUE_REFERENCE_H
11
12#include <__config>
13#include <__type_traits/is_referenceable.h>
14
15#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
16#  pragma GCC system_header
17#endif
18
19_LIBCPP_BEGIN_NAMESPACE_STD
20
21#if __has_builtin(__add_lvalue_reference)
22
23template <class _Tp>
24using __add_lvalue_reference_t = __add_lvalue_reference(_Tp);
25
26#else
27
28template <class _Tp, bool = __libcpp_is_referenceable<_Tp>::value>
29struct __add_lvalue_reference_impl {
30  typedef _LIBCPP_NODEBUG _Tp type;
31};
32template <class _Tp >
33struct __add_lvalue_reference_impl<_Tp, true> {
34  typedef _LIBCPP_NODEBUG _Tp& type;
35};
36
37template <class _Tp>
38using __add_lvalue_reference_t = typename __add_lvalue_reference_impl<_Tp>::type;
39
40#endif // __has_builtin(__add_lvalue_reference)
41
42template <class _Tp>
43struct add_lvalue_reference {
44  using type _LIBCPP_NODEBUG = __add_lvalue_reference_t<_Tp>;
45};
46
47#if _LIBCPP_STD_VER > 11
48template <class _Tp> using add_lvalue_reference_t = __add_lvalue_reference_t<_Tp>;
49#endif
50
51_LIBCPP_END_NAMESPACE_STD
52
53#endif // _LIBCPP___TYPE_TRAITS_ADD_LVALUE_REFERENCE_H
54