#include <cstddef>

struct wrapped_float
{
    std::size_t value; //Initialize with sizeof(wrapped_float)
    float other; //Actual info
};

constexpr wrapped_float const a{ sizeof(a), 0 }; //OK

struct test1 {
    static constexpr wrapped_float const b{ sizeof(b), 0 }; //Error!
};

struct test2 {
    static constexpr wrapped_float const b{ sizeof(test::b), 0 };
};

struct test3 {
    static constexpr wrapped_float const b{ sizeof(decltype(b)), 0 };
};

int main() {
    return a.value + test1::b.value + test2::b.value + test3::b.value;
}