Macro `impl_partial_eq_for_primitive`

macro_rules! impl_partial_eq_for_primitive {
    ($($t:ty)*) => { ... };
}

Implements PartialEq for primitive types.

Primitive types have a compiler-defined primitive implementation of == and !=. This implements the PartialEq trait in terms of those primitive implementations.

NOTE: Calling this on a non-primitive type (such as ()) leads to an infinitely-looping self-recursive implementation.