Method for `Option<&T>` that converts to `*const T`

I find myself often wanting to go from an Option<&T> to a *const T, which SHOULD be an easy and safe conversion, as every Option<&T> is guaranteed to correspond a *const T identical to it in representation. We already have a conversion, std::pointer::as_ref, the other way around, so I find it strange that the shortest way to do so (without defining a new function) is this:

.map_or(ptr::null(), |x| x)

It's just as easy to do the same for Option<&mut T> -> *mut T, of course, although I can't see the utility in it.

It's not as fundamental as Option<&T> -> *const T, but it would also be nice to have Option<&CStr> -> *const c_char.

Start with the issue's proposed conversions and compare them with the existing std::pointer::as_ref API. Follow the Rust RFC process and related standard-library pointer APIs to determine the desired scope, including Option<&T>, Option<&mut T>, and Option<&CStr>. Done means the API design is resolved and the relevant RFC or implementation work is accepted.