Async Transformers

I was using Compiler API and basically changed program.emit at host.afterProgramCreate just like examples and hooked my transformers into emit function. But one thing i couldn't find anywhere is a async transformer. Im using PostCSS and some other stuff like that and implementing those to a single typescript compiler but some plugins are async in postcss and i cant use them at the moment. Is there any way to implement this that im missing or undocumented ? And in case somebody offers to use webpack my code is mostly javascript based and i need really good static analysis for it with type data included that's also reason i use typescript's api instead of using babel which have those cases mostly covered with plugins. I'm implementing all-in-one solution for my company/community project so ideally it needs to be inside typescript compiler.

Start with the Compiler API entry points named in the issue: program.emit and host.afterProgramCreate, then compare the transformer lifecycle with the asynchronous PostCSS plugins involved. Done means establishing whether async transformers are supported or documenting a concrete, scoped compiler change needed to support them.