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git.ipfire.org Git - thirdparty/gcc.git/blob - libstdc++-v3/testsuite/20_util/result_of/sfinae_friendly_2.cc
1 // { dg-do compile { target c++11 } }
3 // Copyright (C) 2012-2017 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING3. If not see
18 // <http://www.gnu.org/licenses/>.
22 #include <type_traits>
25 struct eat
{ template<typename T
> eat(T
const &) {} };
26 struct not_incrementable
{};
30 auto operator()(T t
) const -> decltype(t
++)
35 typename
std::result_of
<inc(A
)>::type
// sfinae here
42 return not_incrementable();
46 struct never
{ static const bool value
= false; };
51 static_assert(never
<T
>::value
, "duh");
58 typename Fail
<T
>::type
operator()(T
)
63 typename
std::result_of
<Fun(T
)>::type
foo(T
)
70 void result_of_sfinae() {
71 int x
= try_inc(1); // OK
72 not_incrementable y
= try_inc(std::string("foo")); // OK, not_incrementable