is std::string now usable as compile time constant?

First of all, I assume with C++20 we have a constexpr std::string in C++20. If that is the case, it should be possible to write something like:

struct MyType { constexpr MyType(int n_):n{n_}{}; int n; };

template < auto a > struct Something {};
template <> struct Something< MyType{1} > { void Do() { std::cout << "Special One" << std::endl;} };
template <> struct Something< MyType{2} > { void Do() { std::cout << "Super Two" << std::endl;} };


int main()
{
    Something<MyType{1}> s; // works fine as expected
    s.Do();

    Something< std::string("Hallo")> s2; // did not work. See error message below
}

But gcc 10.1 complains, that std::string is not a literal type because the destructor is not constexpr. But if I understand the current standard correctly, std::string should be "fully" constexpr.

I am wrong? Or is the current STL from gcc not c++20 "ready"?

Full error message from gcc 10.1 ( same with current g++ trunk ).

/usr/include/c++/10/bits/basic_string.h:77:11: note: 'std::__cxx11::basic_string<char>' is  not literal because:
   77 |     class basic_string
      |           ^~~~~~~~~~~~
/usr/include/c++/10/bits/basic_string.h:77:11: note:   'std::__cxx11::basic_string<char>' does not have 'constexpr' destructor