25     std::span<               int> s1;  in checkCV()
26     std::span<const          int> s2;  in checkCV()
27     std::span<      volatile int> s3;  in checkCV()
28     std::span<const volatile int> s4;  in checkCV()
34     std::span<               int,0> s1;  in checkCV()
35     std::span<const          int,0> s2;  in checkCV()
36     std::span<      volatile int,0> s3;  in checkCV()
37     std::span<const volatile int,0> s4;  in checkCV()
46     std::span<const T>    s1;  in testConstexprSpan()
47     std::span<const T, 0> s2;  in testConstexprSpan()
58     std::span<const T>    s1;  in testRuntimeSpan()
59     std::span<const T, 0> s2;  in testRuntimeSpan()
82     static_assert( std::is_default_constructible_v<std::span<int, std::dynamic_extent>>, "");  in main()
83     static_assert( std::is_default_constructible_v<std::span<int, 0>>, "");  in main()
84     static_assert(!std::is_default_constructible_v<std::span<int, 2>>, "");  in main()