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66 lines
1.9 KiB
C++
66 lines
1.9 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03
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// <queue>
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// template <class... Args> decltype(auto) emplace(Args&&... args);
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// return type is 'decltype(auto)' in C++17; 'void' before
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// whatever the return type of the underlying container's emplace_back() returns.
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#include <queue>
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#include <cassert>
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#include <list>
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#include "test_macros.h"
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#include "../../../Emplaceable.h"
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template <typename Queue>
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void test_return_type() {
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typedef typename Queue::container_type Container;
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typedef typename Container::value_type value_type;
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typedef decltype(std::declval<Queue>().emplace(std::declval<value_type &>())) queue_return_type;
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#if TEST_STD_VER > 14
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typedef decltype(std::declval<Container>().emplace_back(std::declval<value_type>())) container_return_type;
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static_assert(std::is_same<queue_return_type, container_return_type>::value, "");
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#else
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static_assert(std::is_same<queue_return_type, void>::value, "");
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#endif
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}
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int main()
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{
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test_return_type<std::queue<int> > ();
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test_return_type<std::queue<int, std::list<int> > > ();
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std::queue<Emplaceable> q;
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#if TEST_STD_VER > 14
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typedef Emplaceable T;
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T& r1 = q.emplace(1, 2.5);
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assert(&r1 == &q.back());
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T& r2 = q.emplace(2, 3.5);
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assert(&r2 == &q.back());
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T& r3 = q.emplace(3, 4.5);
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assert(&r3 == &q.back());
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assert(&r1 == &q.front());
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#else
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q.emplace(1, 2.5);
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q.emplace(2, 3.5);
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q.emplace(3, 4.5);
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#endif
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assert(q.size() == 3);
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assert(q.front() == Emplaceable(1, 2.5));
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assert(q.back() == Emplaceable(3, 4.5));
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}
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