Re: DIP66 1.2 (Multiple) alias this. Continuation of work.

[IgorStepanov via Digitalmars-d]

Hello, comrades. Lets put into the schedule reviewing of this PR 
(https://github.com/D-Programming-Language/dmd/pull/3998).
It contains a very much changes and it is hard to maintain its 
performance: each foreign PR may break it.