1 //===----------------------------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 // UNSUPPORTED: c++03 10 11 // <stack> 12 13 // template <class... Args> decltype(auto) emplace(Args&&... args); 14 // return type is 'decltype(auto)' in C++17; 'void' before 15 // whatever the return type of the underlying container's emplace_back() returns. 16 17 #include <stack> 18 #include <cassert> 19 #include <vector> 20 21 #include "test_macros.h" 22 23 #include "../../../Emplaceable.h" 24 25 template <typename Stack> 26 void test_return_type() { 27 typedef typename Stack::container_type Container; 28 typedef typename Container::value_type value_type; 29 typedef decltype(std::declval<Stack>().emplace(std::declval<value_type &>())) stack_return_type; 30 31 #if TEST_STD_VER > 14 32 typedef decltype(std::declval<Container>().emplace_back(std::declval<value_type>())) container_return_type; 33 static_assert(std::is_same<stack_return_type, container_return_type>::value, ""); 34 #else 35 static_assert(std::is_same<stack_return_type, void>::value, ""); 36 #endif 37 } 38 39 int main(int, char**) 40 { 41 test_return_type<std::stack<int> > (); 42 test_return_type<std::stack<int, std::vector<int> > > (); 43 44 std::stack<Emplaceable> q; 45 #if TEST_STD_VER > 14 46 typedef Emplaceable T; 47 T& r1 = q.emplace(1, 2.5); 48 assert(&r1 == &q.top()); 49 T& r2 = q.emplace(2, 3.5); 50 assert(&r2 == &q.top()); 51 T& r3 = q.emplace(3, 4.5); 52 assert(&r3 == &q.top()); 53 #else 54 q.emplace(1, 2.5); 55 q.emplace(2, 3.5); 56 q.emplace(3, 4.5); 57 #endif 58 assert(q.size() == 3); 59 assert(q.top() == Emplaceable(3, 4.5)); 60 61 return 0; 62 } 63