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 counted_iterator& operator-=(iter_difference_t<I> n) 12 // requires random_access_iterator<I>; 13 14 #include <iterator> 15 16 #include "test_macros.h" 17 #include "test_iterators.h" 18 19 template<class Iter> 20 concept MinusEqEnabled = requires(Iter& iter) { 21 iter -= 1; 22 }; 23 24 constexpr bool test() { 25 int buffer[8] = {1, 2, 3, 4, 5, 6, 7, 8}; 26 27 { 28 using Counted = std::counted_iterator<random_access_iterator<int*>>; 29 Counted iter(random_access_iterator<int*>{buffer + 2}, 6); 30 assert((iter -= 2) == Counted(random_access_iterator<int*>{buffer}, 8)); 31 assert((iter -= 0) == Counted(random_access_iterator<int*>{buffer}, 8)); 32 assert(iter.count() == 8); 33 34 ASSERT_SAME_TYPE(decltype(iter -= 2), Counted&); 35 } 36 { 37 using Counted = std::counted_iterator<contiguous_iterator<int*>>; 38 Counted iter(contiguous_iterator<int*>{buffer + 2}, 6); 39 assert((iter -= 2) == Counted(contiguous_iterator<int*>{buffer}, 8)); 40 assert((iter -= 0) == Counted(contiguous_iterator<int*>{buffer}, 8)); 41 assert(iter.count() == 8); 42 43 ASSERT_SAME_TYPE(decltype(iter -= 2), Counted&); 44 } 45 { 46 static_assert( MinusEqEnabled< std::counted_iterator<random_access_iterator<int*>>>); 47 static_assert(!MinusEqEnabled<const std::counted_iterator<random_access_iterator<int*>>>); 48 } 49 50 51 return true; 52 } 53 54 int main(int, char**) { 55 test(); 56 static_assert(test()); 57 58 return 0; 59 } 60