constexpr initializing static member using static function

Question

Requirements

I want a constexpr value (i.e. a compile-time constant) computed from a constexpr function. And I want both of these scoped

Answer 1

#include 

class C1 
{
public:
    constexpr static int foo(constexpr int x)
    { 
        return x + 1;
    }

    static constexpr int bar;
};

constexpr int C1::bar = C1::foo(sizeof(int));

int main()
{
    std::cout << C1::bar << std::endl;
    return 0;
}

Such initialization works well but only on clang