[D-runtime] Supporting different C libraries and architectures

[David Nadlinger]

Just a few quick ideas, I must admit that I didn't really think the 
issue through yet:

On 26 Feb 2012, at 14:32, Johannes Pfau wrote:
> Kagamin suggested to add complete glibc, bionic, etc bindings to 
> deimos, then core.* could publically import the approriate modules 
> from deimos. […]

This poses a question though: If we already have the files in Deimos, 
why offer the interfaces through druntime at all (besides backwards 
compatibility)? Which parts of Posix, … should be offered through 
core.*?

> Seems like a good idea to me. We'd need some way to determine the used 
> C library with static if(), to import the correct files, […]

Just a -version switch defined in dmd.conf/sc.ini (resp. ldc.conf, or 
the GDC equivalent) seems like a fine solution for me. It would probably 
mapped to an enum by a druntime module for easier handling, and if not 
present, we could simply print out a pragma(msg) and default to glibc 
where appropriate to offer a smooth transition for people who don't 
routinely upgrade their DMD config files.

> Technically this means druntime depends on deimos, but those are only 
> bindings which could be compiled/shipped with druntime.

Note aside: Deimos bindings never ever need to be compiled. If they do 
require linking in symbols besides the C library itself, it's a bug (at 
least in my opinion).


David