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, c++11, c++14, c++17 10 11 // constexpr iterator& operator--() requires decrementable<W>; 12 // constexpr iterator operator--(int) requires decrementable<W>; 13 14 #include <cassert> 15 #include <ranges> 16 #include <type_traits> 17 18 #include "test_macros.h" 19 #include "../types.h" 20 21 template<class T> 22 concept Decrementable = 23 requires(T i) { 24 --i; 25 } || 26 requires(T i) { 27 i--; 28 }; 29 test()30constexpr bool test() { 31 { 32 std::ranges::iota_view<int> io(0); 33 auto iter1 = std::next(io.begin()); 34 auto iter2 = std::next(io.begin()); 35 assert(iter1 == iter2); 36 assert(--iter1 != iter2--); 37 assert(iter1 == iter2); 38 39 static_assert(!std::is_reference_v<decltype(iter2--)>); 40 static_assert( std::is_reference_v<decltype(--iter2)>); 41 static_assert(std::same_as<std::remove_reference_t<decltype(--iter2)>, decltype(iter2--)>); 42 } 43 { 44 std::ranges::iota_view io(SomeInt(0)); 45 auto iter1 = std::next(io.begin()); 46 auto iter2 = std::next(io.begin()); 47 assert(iter1 == iter2); 48 assert(--iter1 != iter2--); 49 assert(iter1 == iter2); 50 51 static_assert(!std::is_reference_v<decltype(iter2--)>); 52 static_assert( std::is_reference_v<decltype(--iter2)>); 53 static_assert(std::same_as<std::remove_reference_t<decltype(--iter2)>, decltype(iter2--)>); 54 } 55 56 static_assert(!Decrementable<std::ranges::iota_view<NotDecrementable>>); 57 58 return true; 59 } 60 main(int,char **)61int main(int, char**) { 62 test(); 63 static_assert(test()); 64 65 return 0; 66 } 67