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 { 33 std::uint16_t size() const { return 60000; } // not noexcept 34 }; 35 36 template<typename 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> 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> 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> 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> 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 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(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