Macro __impl_inferbase 

#[doc(hidden)]
macro_rules! __impl_inferbase {
    ($ty:ty, $base:ident, $make_fn:path, $install_fn:ident) => { ... };
}

Parametric implementation of InferBase for any ALTREP family.

Takes the type, RBase variant, R_make_alt*_class function, and family installer.