{dmd, druntime} -> {dmd+druntime} i.e. Monorepo?

[Dukc]

On Monday, 23 August 2021 at 07:51:52 UTC, IGotD- wrote:
> Yes, if you for example want to develop a special druntime, 
> then it is better to have dmd and druntime separated as you 
> don't need the extra dmd baggage.
>
> A similar argument can be done to merge phobos and druntime 
> because they are somewhat connected as well. I'm not suggesting 
> this however.

These two are totally dissimilar cases.

Everything in `core` is part of the language. Any D compiler is 
allowed to specially recognize functions in the `core` API. And 
vice-versa, any D compiler is allowed to translate language 
constructs to DRuntime calls. The latter is done in DMD for 
`assert` failures and `new`, for example. It follows that what 
DRuntime is fundamentally dependent on the compiler 
implementation, and there is a good case for having a same 
repository for both of them.

Conversely the `std` is just a library that obeys normal language 
rules. It's implementation should try to avoid compiler 
implementation dependency where possible, and no D compiler 
should handle anything in `std` namespace as special. Ideally, 
you could compile multiple different versions of Phobos with any 
D compiler. I don't think Phobos is nearly that portable in 
practice but that's the ideal. It follows that it should always 
be a separate repository from the compiler and/or DRuntime.