Type Alias NonZeroI64

pub type NonZeroI64 = NonZero<i64>;

An integer that is known not to equal zero.

This enables some memory layout optimization. For example, Option<NonZeroI64> is the same size as i64:

use std::mem::size_of;
assert_eq!(size_of::<Option<core::num::NonZeroI64>>(), size_of::<i64>());

Layout

NonZeroI64 is guaranteed to have the same layout and bit validity as i64 with the exception that 0 is not a valid instance. Option<NonZeroI64> is guaranteed to be compatible with i64, including in FFI.

Thanks to the null pointer optimization, NonZeroI64 and Option<NonZeroI64> are guaranteed to have the same size and alignment:

use std::num::NonZeroI64;

assert_eq!(size_of::<NonZeroI64>(), size_of::<Option<NonZeroI64>>());
assert_eq!(align_of::<NonZeroI64>(), align_of::<Option<NonZeroI64>>());

Aliased Type

struct NonZeroI64(/* private fields */);