Macro __impl_alt_get_region 

#[doc(hidden)]
macro_rules! __impl_alt_get_region {
    ($ty:ty, $trait:path, $buf_ty:ty) => { ... };
}

Shared get_region implementation for ALTREP families.

Generates const HAS_GET_REGION and fn get_region(...) inside an impl block. Used by integer, real, logical, raw, and complex families.