Macro register_intrinsic 

macro_rules! register_intrinsic {
    ($def:expr $(,)?) => { ... };
}

Register a built-in intrinsic with the global registry.

Takes a unit-struct value implementing Intrinsic; the registry stores it as a &'static dyn Intrinsic.

struct Rol;
impl Intrinsic for Rol { /* … */ }
register_intrinsic!(Rol);