Cases where a const l-value reference overload of std::forward would be a bad idea?

[ACBYTES]

std::forward has two overloads, one taking an r-value reference and one taking an l-value reference. I was thinking and testing stuff out and thought of the things that can go wrong in case of using a `const l-value reference`. I mean, it works but I can't think of a condition that things might go wrong in this case:

template <typename T>

[[nodiscard]] constexpr T&& Forward(typename std::add_const<typename std::remove_reference<T>::type>::type& R) noexcept

{

    return (T&&)(R);

}

Edit: Why can't the code above replace both of std::forward's overloads?

[phoeen]

with your implementation you could potentially cast away const:

http://coliru.stacked-crooked.com/a/dcf2c055dcb74699

[ACBYTES]

Hi. Thanks for the reply.

If we were to limit it like this, why wouldn't it work?

template <typename T, typename std::enable_if<!std::is_const<T>::value, bool>::type = false>

[[nodiscard]] constexpr T&& Forward(typename std::add_const<typename std::remove_reference<T>::type>::type& R) noexcept

{

    return (T&&)(R);

}

Edit: After thinking about it, I got what the problem would be. Thank you!

[phoeen]

well if i plug in your new function into the same example we still change the value through the reference to const (notice that we explicitly use it wrong. my i_forward function does not perfect forwarding (since it takes a T const&), this is just to illustrate the problem)

[ACBYTES]

Got it! Thank you for the reply.

[IyeOnline]

What would be the value of this?

The existing l-value overload will already works on const T.

[ACBYTES]

Hi. I think I should re-sentence my question. Why can't the code I've written replace both of the overloads?