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 // <iterator>
12 // template <class C> constexpr auto ssize(const C& c)
13 // -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>; // C++20
14 // template <class T, ptrdiff_t> constexpr ptrdiff_t ssize(const T (&array)[N]) noexcept; // C++20
15
16 #include <array>
17 #include <cassert>
18 #include <cstdint>
19 #include <initializer_list>
20 #include <iterator>
21 #include <limits>
22 #include <list>
23 #include <string_view>
24 #include <type_traits>
25 #include <vector>
26
27 #include "test_macros.h"
28
29 // Ignore warning about std::numeric_limits comparisons being tautological.
30 TEST_GCC_DIAGNOSTIC_IGNORED("-Wtype-limits")
31
32 struct short_container {
sizeshort_container33 std::uint16_t size() const { return 60000; } // not noexcept
34 };
35
36 template<typename C>
test_container(C & c)37 void test_container(C& c)
38 {
39 // Can't say noexcept here because the container might not be
40 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
41 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
42 }
43
44 template<typename C>
test_const_container(const C & c)45 void test_const_container(const C& c)
46 {
47 // Can't say noexcept here because the container might not be
48 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
49 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
50 }
51
52 template<typename T>
test_const_container(const std::initializer_list<T> & c)53 void test_const_container(const std::initializer_list<T>& c)
54 {
55 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept
56 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
57 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
58 }
59
60 template<typename T>
test_container(std::initializer_list<T> & c)61 void test_container(std::initializer_list<T>& c)
62 {
63 LIBCPP_ASSERT_NOEXCEPT(std::ssize(c)); // our std::ssize is conditionally noexcept
64 static_assert( std::is_signed_v<decltype(std::ssize(c))>, "");
65 assert ( std::ssize(c) == static_cast<decltype(std::ssize(c))>(c.size()));
66 }
67
68 template<typename T, std::size_t Sz>
test_const_array(const T (& array)[Sz])69 void test_const_array(const T (&array)[Sz])
70 {
71 ASSERT_NOEXCEPT(std::ssize(array));
72 static_assert( std::is_signed_v<decltype(std::ssize(array))>, "");
73 assert ( std::ssize(array) == Sz );
74 }
75
main(int,char **)76 int main(int, char**)
77 {
78 std::vector<int> v; v.push_back(1);
79 std::list<int> l; l.push_back(2);
80 std::array<int, 1> a; a[0] = 3;
81 std::initializer_list<int> il = { 4 };
82 using SSize = std::common_type_t<std::ptrdiff_t, std::make_signed_t<std::size_t>>;
83 test_container ( v );
84 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(v)));
85 test_container ( l );
86 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(l)));
87 test_container ( a );
88 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(a)));
89 test_container ( il );
90 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(il)));
91
92 test_const_container ( v );
93 test_const_container ( l );
94 test_const_container ( a );
95 test_const_container ( il );
96
97 std::string_view sv{"ABC"};
98 test_container ( sv );
99 ASSERT_SAME_TYPE(SSize, decltype(std::ssize(sv)));
100 test_const_container ( sv );
101
102 static constexpr int arrA [] { 1, 2, 3 };
103 ASSERT_SAME_TYPE(std::ptrdiff_t, decltype(std::ssize(arrA)));
104 static_assert( std::is_signed_v<decltype(std::ssize(arrA))>, "");
105 test_const_array ( arrA );
106
107 // From P1227R2:
108 // Note that the code does not just return the std::make_signed variant of
109 // the container's size() method, because it's conceivable that a container
110 // might choose to represent its size as a uint16_t, supporting up to
111 // 65,535 elements, and it would be a disaster for std::ssize() to turn a
112 // size of 60,000 into a size of -5,536.
113
114 short_container sc;
115 // is the return type signed? Is it big enough to hold 60K?
116 // is the "signed version" of sc.size() too small?
117 static_assert( std::is_signed_v< decltype(std::ssize(sc))>, "");
118 static_assert( std::numeric_limits< decltype(std::ssize(sc))>::max() > 60000, "");
119 static_assert( std::numeric_limits<std::make_signed_t<decltype(std:: size(sc))>>::max() < 60000, "");
120 assert (std::ssize(sc) == 60000);
121 LIBCPP_ASSERT_NOT_NOEXCEPT(std::ssize(sc));
122
123 return 0;
124 }
125