Hi,

It is currently impossible to create a std::span from std::array<const T, X>:

    

std::array<const int, 4> a = {1, 2, 3, 4};

    std::span<const int> s{a}; // No overload can be found.

std::span s{a}; // CTAD doesn't help either.

Whereas constructing a std::span from a C-array is perfectly valid:

 

const int a[] = {1, 2, 3, 4};

std::span<const int> s{a}; // It works

Is there any reason for the template<size_t N> constexpr span(const array<value_type, N>& arr) noexcept overload not to take by element_type as the overload for C-array does? Is there any other solution to that problem?

gls::span had a constructor for a generic const Container constructor that does not SFINAE if the Containter type is a std::array:

Is that something we want in the standard? In other words, could we relax the two constraints (14.3) Container is not a specialization of array, (14.4) is_­array_­v<Container> is false, on the template<class Container> constexpr span(const Container& cont) overload?

It possible to manually extract the a pointer and a size from a std::array and feed it to a std::span, but I really think that these two classes ought to work well together out of the box!

Sincerely,

Jean Guegant