Projects to the index-th element of slice_ptr, as the same kind of pointer as the slice was provided -- so &mut [T] → &mut T, &[T] → &T, *mut [T] → *mut T, or *const [T] → *const T -- without a bounds check.

This is exposed via <usize as SliceIndex>::get(_unchecked)(_mut), and isn't intended to be used elsewhere.

Expands in MIR to {&, &mut, &raw const, &raw mut} (*slice_ptr)[index], depending on the types involved, so no backend support is needed.

Safety

• index < PtrMetadata(slice_ptr), so the indexing is in-bounds for the slice
• the resulting offsetting is in-bounds of the allocation, which is always the case for references, but needs to be upheld manually for pointers