According to cppreference, bit-fields can only be captured by copy: https://en.cppreference.com/w/cpp/language/lambda. Period.

At the same time, one can see certain scenarios, e.g.:

struct U {
    int i : 4;
};

constexpr int foo() {
    const auto & [y] = U{5};
    return [&y = y]() { return y; }();
}

static_assert( foo() == 5 );

where both GCC and Clang permit capture of bit-fields by reference even during evaluation of constant expressions. Online demo: https://gcc.godbolt.org/z/bcbqcGKd7

Are there any exceptions not mentioned in cppreference or proposals to future C++ standards, which legalize capture of bit-fields by reference?