RFC: Move runtime hook definitions to a .di file in druntime

[Kevin Lamonte via D.gnu]

On Sunday, 12 October 2014 at 00:12:47 UTC, Mike wrote:
> Sounds like you you and I are after pretty much the same thing.
>  I'm not really trying to build anything, like a kernel, just 
> yet.
>  Rather, I'm just trying to get a decent runtime built so we 
> can all have a reasonably polished language to work with.
>
> You can find my work here: 
> https://github.com/JinShil/druntime_level_0.  I'm afraid it's 
> not any further along then yours.  I actually became quite 
> discouraged and stalled.  I'm trying to explore other options, 
> hence this post.

Thank you for the pointer, I'll be checking in periodically.

I'm linking now with a restricted subset of druntime, and capable 
of minimally using structs and enums.  (That's actually almost 
enough to write a C-language kernel using GDC. :-) )

I am thinking of two useful outcomes from this GDC feature 
request:

1. A "libd.di" listing all of the extern function signatures the 
compiler can automatically insert.  (They can remain in mangled 
form for now, ddemangle does good enough.)  This would clear the 
way for many new runtimes to be built.

2. Initiate discussion between GDC/LDC2/DMD on one or more 
version labels for druntime features (what you have as level0, 
level1, etc.).  This would not only help enable new runtimes feed 
implementations back to upstream druntime, it would also help 
identify where druntime can be refactored for internal 
decoupling.  This would permit things like pluggable GCs.