1 // Copyright (C) 2019-2022 Free Software Foundation, Inc.
3 // This file is part of the GNU ISO C++ Library. This library is free
4 // software; you can redistribute it and/or modify it under the
5 // terms of the GNU General Public License as published by the
6 // Free Software Foundation; either version 3, or (at your option)
9 // This library is distributed in the hope that it will be useful,
10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 // GNU General Public License for more details.
14 // You should have received a copy of the GNU General Public License along
15 // with this library; see the file COPYING3. If not see
16 // <http://www.gnu.org/licenses/>.
18 // { dg-options "-std=gnu++2a" }
19 // { dg-do compile { target c++2a } }
23 // C++20 [func.identity]
24 static_assert( std::is_default_constructible_v
<std::identity
> );
25 static_assert( std::is_copy_constructible_v
<std::identity
> );
26 static_assert( std::is_move_constructible_v
<std::identity
> );
27 static_assert( std::is_copy_assignable_v
<std::identity
> );
28 static_assert( std::is_move_assignable_v
<std::identity
> );
30 static_assert( !std::is_invocable_v
<std::identity
> );
31 static_assert( !std::is_invocable_v
<std::identity
, int&, int&> );
32 static_assert( std::is_nothrow_invocable_r_v
<int&, std::identity
&, int&> );
33 static_assert( std::is_nothrow_invocable_r_v
<const long&, std::identity
, const long&> );
34 static_assert( std::is_nothrow_invocable_r_v
<short&&, const std::identity
&, short> );
35 static_assert( std::is_nothrow_invocable_r_v
<const char&&, const std::identity
, const char> );
38 static_assert( std::addressof(std::identity
{}(i
)) == std::addressof(i
) );
40 using T
= std::identity::is_transparent
; // required typedef