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 template <class _Tp>
23 struct add_lvalue_reference {
24   using type _LIBCPP_NODEBUG = __add_lvalue_reference(_Tp);
25 };
26 #else
27 template <class _Tp, bool = __libcpp_is_referenceable<_Tp>::value>
28 struct __add_lvalue_reference_impl {
29   typedef _LIBCPP_NODEBUG _Tp type;
30 };
31 template <class _Tp                                       > struct __add_lvalue_reference_impl<_Tp, true> { typedef _LIBCPP_NODEBUG _Tp& type; };
32 
33 template <class _Tp> struct _LIBCPP_TEMPLATE_VIS add_lvalue_reference
34 {typedef _LIBCPP_NODEBUG typename  __add_lvalue_reference_impl<_Tp>::type type;};
35 #endif // __has_builtin(__add_lvalue_reference)
36 
37 #if _LIBCPP_STD_VER > 11
38 template <class _Tp> using add_lvalue_reference_t = typename add_lvalue_reference<_Tp>::type;
39 #endif
40 
41 _LIBCPP_END_NAMESPACE_STD
42 
43 #endif // _LIBCPP___TYPE_TRAITS_ADD_LVALUE_REFERENCE_H
44