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 // <iterator>
10
11 // All of these became constexpr in C++17
12 //
13 // template <InputIterator Iter, class Distance>
14 // constexpr void advance(Iter& i, Distance n);
15 //
16 // template <BidirectionalIterator Iter, class Distance>
17 // constexpr void advance(Iter& i, Distance n);
18 //
19 // template <RandomAccessIterator Iter, class Distance>
20 // constexpr void advance(Iter& i, Distance n);
21
22 // Make sure we catch forced conversions to the difference_type if they happen.
23 // ADDITIONAL_COMPILE_FLAGS: -Wsign-conversion
24
25 #include <iterator>
26 #include <cassert>
27 #include <cstddef>
28 #include <type_traits>
29
30 #include "test_macros.h"
31 #include "test_iterators.h"
32
33 template <class Distance, class It>
34 TEST_CONSTEXPR_CXX17
check_advance(It it,Distance n,It result)35 void check_advance(It it, Distance n, It result)
36 {
37 static_assert(std::is_same<decltype(std::advance(it, n)), void>::value, "");
38 std::advance(it, n);
39 assert(it == result);
40 }
41
tests()42 TEST_CONSTEXPR_CXX17 bool tests()
43 {
44 const char* s = "1234567890";
45
46 // Check with iterator_traits::difference_type
47 {
48 typedef std::iterator_traits<const char*>::difference_type Distance;
49 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
50 check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
51 check_advance<Distance>(bidirectional_iterator<const char*>(s+5), 5, bidirectional_iterator<const char*>(s+10));
52 check_advance<Distance>(bidirectional_iterator<const char*>(s+5), -5, bidirectional_iterator<const char*>(s));
53 check_advance<Distance>(random_access_iterator<const char*>(s+5), 5, random_access_iterator<const char*>(s+10));
54 check_advance<Distance>(random_access_iterator<const char*>(s+5), -5, random_access_iterator<const char*>(s));
55 check_advance<Distance>(s+5, 5, s+10);
56 check_advance<Distance>(s+5, -5, s);
57 }
58
59 // Also check with other distance types
60 {
61 typedef int Distance;
62 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10, cpp17_input_iterator<const char*>(s+10));
63 check_advance<Distance>(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
64 check_advance<Distance>(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10));
65 check_advance<Distance>(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10));
66 }
67
68 // Check with unsigned distance types to catch signedness-change issues
69 {
70 typedef std::size_t Distance;
71 check_advance<Distance>(cpp17_input_iterator<const char*>(s), 10u, cpp17_input_iterator<const char*>(s+10));
72 check_advance<Distance>(forward_iterator<const char*>(s), 10u, forward_iterator<const char*>(s+10));
73 check_advance<Distance>(bidirectional_iterator<const char*>(s), 10u, bidirectional_iterator<const char*>(s+10));
74 check_advance<Distance>(random_access_iterator<const char*>(s), 10u, random_access_iterator<const char*>(s+10));
75 }
76
77 return true;
78 }
79
main(int,char **)80 int main(int, char**)
81 {
82 tests();
83 #if TEST_STD_VER >= 17
84 static_assert(tests(), "");
85 #endif
86 return 0;
87 }
88