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//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11, c++14
// template <class T> constexpr add_const<T>& as_const(T& t) noexcept; // C++17
// template <class T> add_const<T>& as_const(const T&&) = delete; // C++17
#include <utility>
#include <cassert>
struct S {int i;};
bool operator==(const S& x, const S& y) { return x.i == y.i; }
bool operator==(const volatile S& x, const volatile S& y) { return x.i == y.i; }
template<typename T>
void test(T& t)
{
static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const (t))>::type>::value, "");
static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const< T>(t))>::type>::value, "");
static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<const T>(t))>::type>::value, "");
static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<volatile T>(t))>::type>::value, "");
static_assert(std::is_const<typename std::remove_reference<decltype(std::as_const<const volatile T>(t))>::type>::value, "");
assert(std::as_const(t) == t);
assert(std::as_const< T>(t) == t);
assert(std::as_const<const T>(t) == t);
assert(std::as_const<volatile T>(t) == t);
assert(std::as_const<const volatile T>(t) == t);
}
int main()
{
int i = 3;
double d = 4.0;
S s{2};
test(i);
test(d);
test(s);
}
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