Speeding up importing Phobos files

[KnightMare]

On Saturday, 8 June 2019 at 11:58:36 UTC, Adam D. Ruppe wrote:
>> +1 for AST.
>
> This doesn't make a significant difference. Parsing D source 
> into an AST is quick and easy. The problem is applying that ast 
> to user types.

one more idea. allow to store in AST-packages user/any metadata.
LDC can store there optimized LLVM-IR code for AST-tree, so 
compilation time will be: compile user code only, link and write 
result to FS