Migrating dmd to D?

[Daniel Murphy]

"David Nadlinger" <see at klickverbot.at> wrote in message 
news:tbfgbhevqojgnawnxgns at forum.dlang.org...
>
> Second, rewriting all of *LDC's* code in D would be a huge task, as the 
> use of C++ templates is pervasive through the LLVM C++ API (even if they 
> are used pretty judiciously), and the LLVM C API is a lot less powerful in 
> some aspects. Thus, care should be taken that the D frontend can actually 
> be used with some of the virtual method implementations still in C++ (e.g. 
> toElem/toElemDtor and similar LDC-specific ones).
>
> Your (Andrei's) initial post sounded like this would be the case. But if I 
> interpreted some of the posts correctly, Daniel Murphy has an automatic 
> translator in the works for porting over the whole compiler (except for 
> the backend) at once, which might be a problem for LDC.
>
> David

I think we can solve this, but it's a lot of work.

1. Refactor the glue layer to use a proper visitor pattern
2. Implement extern(C++) classes (where 
https://github.com/D-Programming-Language/dmd/pull/644 was supposed to be 
headed)

This should allow us to have the dmd glue layer written in D, with the 
ldc/gdc glue layers written in c++.

It would require all three glue layers to be refactored together, but I 
don't see a way to avoid this.  Hopefully we can get rid of most of the 
gdc/ldc specific frontend patches along the way.

What do you and Iain think about this approach?