Type Alias NonZeroU16

pub type NonZeroU16 = NonZero<u16>;

A u16 that is known not to equal zero.

This enables some memory layout optimization. For example, Option<NonZeroU16> is the same size as u16:

use std::mem::size_of;
assert_eq!(size_of::<Option<core::num::NonZeroU16>>(), size_of::<u16>());

Layout

NonZeroU16 is guaranteed to have the same layout and bit validity as u16 with the exception that 0 is not a valid instance. Option<NonZeroU16> is guaranteed to be compatible with u16, including in FFI.

Thanks to the null pointer optimization, NonZeroU16 and Option<NonZeroU16> are guaranteed to have the same size and alignment:

use std::num::NonZeroU16;

assert_eq!(size_of::<NonZeroU16>(), size_of::<Option<NonZeroU16>>());
assert_eq!(align_of::<NonZeroU16>(), align_of::<Option<NonZeroU16>>());

Aliased Type

struct NonZeroU16(/* private fields */);