Remove MaybeUninit::slice_as_(mut_)ptr and optionally add *const/*mut MaybeUninit<T> -> *const/*mut T type safe conversions #245
Description
Proposal
This ACP breaks off a small piece of #122 that wasn't discussed in depth.
Problem statement
The MaybeUninit::slice_as_(mut_)ptr methods force you to elide bounds checks to go from MaybeUninit<T> to T.
fn slice_as_ptr(this: &[MaybeUninit<T>]) -> *const TMotivating examples or use cases
There is evidence of unnecessary bounds elision occurring in the stdlib: notice the places that were switched to using array indexing in rust-lang/rust@f2e9b40.
Solution sketch
Remove MaybeUninit::slice_as_(mut_)ptr.
Optionally, I'd like to add methods for *const/*mut MaybeUninit<T> -> *const/*mut T. This restores the type safety provided by slice_as_ptr and enables improved type safety in other cases where one has a raw pointer to a MaybeUninit and wishes to get at the wrapped type. Without these methods, you'd just have to do the cast manually which isn't the end of the world.
impl<T> *const MaybeUninit<T> {
pub const fn raw_as_ptr(self) -> *const T
}
impl<T> *mut MaybeUninit<T> {
pub const fn raw_as_mut_ptr(self) -> *mut T
}