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 // UNSUPPORTED: c++03, c++11, c++14, c++17
9 
10 // <span>
11 
12 // template<class OtherElementType, size_t OtherExtent>
13 //    constexpr span(const span<OtherElementType, OtherExtent>& s) noexcept;
14 //
15 //  Remarks: This constructor shall not participate in overload resolution unless:
16 //      Extent == dynamic_extent || Extent == OtherExtent is true, and
17 //      OtherElementType(*)[] is convertible to ElementType(*)[].
18 
19 
20 #include <span>
21 #include <cassert>
22 #include <string>
23 
24 #include "test_macros.h"
25 
26 template<class T, size_t extent, size_t otherExtent>
27 std::span<T, extent> createImplicitSpan(std::span<T, otherExtent> s) {
28     return {s}; // expected-error {{chosen constructor is explicit in copy-initialization}}
29 }
30 
31 void checkCV ()
32 {
33 //  std::span<               int>   sp;
34     std::span<const          int>  csp;
35     std::span<      volatile int>  vsp;
36     std::span<const volatile int> cvsp;
37 
38 //  std::span<               int, 0>   sp0;
39     std::span<const          int, 0>  csp0;
40     std::span<      volatile int, 0>  vsp0;
41     std::span<const volatile int, 0> cvsp0;
42 
43 //  Try to remove const and/or volatile (dynamic -> dynamic)
44     {
45     std::span<               int> s1{ csp}; // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
46     std::span<               int> s2{ vsp}; // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
47     std::span<               int> s3{cvsp}; // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
48 
49     std::span<const          int> s4{ vsp}; // expected-error {{no matching constructor for initialization of 'std::span<const int>'}}
50     std::span<const          int> s5{cvsp}; // expected-error {{no matching constructor for initialization of 'std::span<const int>'}}
51 
52     std::span<      volatile int> s6{ csp}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int>'}}
53     std::span<      volatile int> s7{cvsp}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int>'}}
54     }
55 
56 //  Try to remove const and/or volatile (static -> static)
57     {
58     std::span<               int, 0> s1{ csp0}; // expected-error {{no matching constructor for initialization of 'std::span<int, 0>'}}
59     std::span<               int, 0> s2{ vsp0}; // expected-error {{no matching constructor for initialization of 'std::span<int, 0>'}}
60     std::span<               int, 0> s3{cvsp0}; // expected-error {{no matching constructor for initialization of 'std::span<int, 0>'}}
61 
62     std::span<const          int, 0> s4{ vsp0}; // expected-error {{no matching constructor for initialization of 'std::span<const int, 0>'}}
63     std::span<const          int, 0> s5{cvsp0}; // expected-error {{no matching constructor for initialization of 'std::span<const int, 0>'}}
64 
65     std::span<      volatile int, 0> s6{ csp0}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int, 0>'}}
66     std::span<      volatile int, 0> s7{cvsp0}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int, 0>'}}
67     }
68 
69 //  Try to remove const and/or volatile (static -> dynamic)
70     {
71     std::span<               int> s1{ csp0}; // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
72     std::span<               int> s2{ vsp0}; // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
73     std::span<               int> s3{cvsp0}; // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
74 
75     std::span<const          int> s4{ vsp0}; // expected-error {{no matching constructor for initialization of 'std::span<const int>'}}
76     std::span<const          int> s5{cvsp0}; // expected-error {{no matching constructor for initialization of 'std::span<const int>'}}
77 
78     std::span<      volatile int> s6{ csp0}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int>'}}
79     std::span<      volatile int> s7{cvsp0}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int>'}}
80     }
81 
82 //  Try to remove const and/or volatile (static -> static)
83     {
84     std::span<               int, 0> s1{ csp}; // expected-error {{no matching constructor for initialization of 'std::span<int, 0>'}}
85     std::span<               int, 0> s2{ vsp}; // expected-error {{no matching constructor for initialization of 'std::span<int, 0>'}}
86     std::span<               int, 0> s3{cvsp}; // expected-error {{no matching constructor for initialization of 'std::span<int, 0>'}}
87 
88     std::span<const          int, 0> s4{ vsp}; // expected-error {{no matching constructor for initialization of 'std::span<const int, 0>'}}
89     std::span<const          int, 0> s5{cvsp}; // expected-error {{no matching constructor for initialization of 'std::span<const int, 0>'}}
90 
91     std::span<      volatile int, 0> s6{ csp}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int, 0>'}}
92     std::span<      volatile int, 0> s7{cvsp}; // expected-error {{no matching constructor for initialization of 'std::span<volatile int, 0>'}}
93     }
94 }
95 
96 int main(int, char**)
97 {
98     std::span<int>      sp;
99     std::span<int, 0>   sp0;
100 
101     std::span<float> s1{sp};    // expected-error {{no matching constructor for initialization of 'std::span<float>'}}
102     std::span<float> s2{sp0};   // expected-error {{no matching constructor for initialization of 'std::span<float>'}}
103     std::span<float, 0> s3{sp}; // expected-error {{no matching constructor for initialization of 'std::span<float, 0>'}}
104     std::span<float, 0> s4{sp0};    // expected-error {{no matching constructor for initialization of 'std::span<float, 0>'}}
105 
106     checkCV();
107 
108     // explicit constructor necessary
109     {
110     createImplicitSpan<int, 1>(sp);
111     }
112 
113   return 0;
114 }
115