I've created pull request, which introduces multiple alias this. https://github.com/D-Programming-Language/dmd/pull/3998 Please see the additional tests and comment it.
Further, could this also be used to somehow simplify hierarchically defined enumerators? Typically the enumerators and predicates related to the enumeration WordKind defined here
https://github.com/nordlow/justd/blob/master/languages.d#L485
