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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef TRANSPARENT_H
#define TRANSPARENT_H
#include "test_macros.h"
#include <functional> // for std::equal_to
// testing transparent
#if TEST_STD_VER > 11
struct transparent_less
{
template <class T, class U>
constexpr auto operator()(T&& t, U&& u) const
noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
-> decltype (std::forward<T>(t) < std::forward<U>(u))
{ return std::forward<T>(t) < std::forward<U>(u); }
using is_transparent = void; // correct
};
struct transparent_less_not_referenceable
{
template <class T, class U>
constexpr auto operator()(T&& t, U&& u) const
noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
-> decltype (std::forward<T>(t) < std::forward<U>(u))
{ return std::forward<T>(t) < std::forward<U>(u); }
using is_transparent = void () const &; // it's a type; a weird one, but a type
};
struct transparent_less_no_type
{
template <class T, class U>
constexpr auto operator()(T&& t, U&& u) const
noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
-> decltype (std::forward<T>(t) < std::forward<U>(u))
{ return std::forward<T>(t) < std::forward<U>(u); }
private:
// using is_transparent = void; // error - should exist
};
struct transparent_less_private
{
template <class T, class U>
constexpr auto operator()(T&& t, U&& u) const
noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
-> decltype (std::forward<T>(t) < std::forward<U>(u))
{ return std::forward<T>(t) < std::forward<U>(u); }
private:
using is_transparent = void; // error - should be accessible
};
struct transparent_less_not_a_type
{
template <class T, class U>
constexpr auto operator()(T&& t, U&& u) const
noexcept(noexcept(std::forward<T>(t) < std::forward<U>(u)))
-> decltype (std::forward<T>(t) < std::forward<U>(u))
{ return std::forward<T>(t) < std::forward<U>(u); }
int is_transparent; // error - should be a type
};
struct C2Int { // comparable to int
C2Int() : i_(0) {}
C2Int(int i): i_(i) {}
int get () const { return i_; }
private:
int i_;
};
bool operator <(int rhs, const C2Int& lhs) { return rhs < lhs.get(); }
bool operator <(const C2Int& rhs, const C2Int& lhs) { return rhs.get() < lhs.get(); }
bool operator <(const C2Int& rhs, int lhs) { return rhs.get() < lhs; }
#endif // TEST_STD_VER > 11
#endif // TRANSPARENT_H
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