std::slice::from_raw_parts alternative that would accept a null pointer if len == 0 by returning an empty slice

Proposal

Problem statement

Currently, it's not allowed to pass a NULL pointer to std::slice::from_raw_parts, but

I have a pointer that comes from a C function that can be either:

A) A non-NULL with a len > 0
B) A NULL with a len == 0

Solution sketch

It would be neat if it was possible to just write something like:

let values = unsafe { std::slice::from_raw_parts_or_empty(c_ptr_to_values, len) }; // Still panic if c_ptr_to_values == NULL and len > 0.
for value in values {
   // This can be skipped if values is an empty slice when c_ptr_to_values == NULL and len == 0.
   // Or values can be iterated when c_ptr_to_values != NULL and len > 0.
}

Start by reading the documented behavior of std::slice::from_raw_parts and the proposal's two C-pointer cases. The issue names no files or tests; done would require a settled library API design for producing an empty slice when the pointer is null and len is zero while rejecting the other null-pointer case.