1 //===----------------------------------------------------------------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is dual licensed under the MIT and the University of Illinois Open 6 // Source Licenses. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 10 // UNSUPPORTED: c++98, c++03 11 12 // <stack> 13 14 // template <class... Args> decltype(auto) emplace(Args&&... args); 15 // return type is 'decltype(auto)' in C++17; 'void' before 16 // whatever the return type of the underlying container's emplace_back() returns. 17 18 #include <stack> 19 #include <cassert> 20 #include <vector> 21 22 #include "test_macros.h" 23 24 #include "../../../Emplaceable.h" 25 26 template <typename Stack> 27 void test_return_type() { 28 typedef typename Stack::container_type Container; 29 typedef typename Container::value_type value_type; 30 typedef decltype(std::declval<Stack>().emplace(std::declval<value_type &>())) stack_return_type; 31 32 #if TEST_STD_VER > 14 33 typedef decltype(std::declval<Container>().emplace_back(std::declval<value_type>())) container_return_type; 34 static_assert(std::is_same<stack_return_type, container_return_type>::value, ""); 35 #else 36 static_assert(std::is_same<stack_return_type, void>::value, ""); 37 #endif 38 } 39 40 int main() 41 { 42 test_return_type<std::stack<int> > (); 43 test_return_type<std::stack<int, std::vector<int> > > (); 44 45 std::stack<Emplaceable> q; 46 #if TEST_STD_VER > 14 47 typedef Emplaceable T; 48 T& r1 = q.emplace(1, 2.5); 49 assert(&r1 == &q.top()); 50 T& r2 = q.emplace(2, 3.5); 51 assert(&r2 == &q.top()); 52 T& r3 = q.emplace(3, 4.5); 53 assert(&r3 == &q.top()); 54 #else 55 q.emplace(1, 2.5); 56 q.emplace(2, 3.5); 57 q.emplace(3, 4.5); 58 #endif 59 assert(q.size() == 3); 60 assert(q.top() == Emplaceable(3, 4.5)); 61 } 62
