Proposal: configuration for cross compilation

[David Nadlinger via digitalmars-d-ldc]

Hi Kai,

On 5 May 2014, at 12:37, Kai Nacke via digitalmars-d-ldc wrote:
> More and more people use LDC to cross-compile for other architectures. 
> But end-to-end support is still missing.

We are in desperate need of improvements on this front, I agree. I have 
been using various kludges to switch between environments and ldc2.conf 
files when cross-compiling myself too. And this in fact should be an 
area where LDC can really shine compared to e.g. GCC-based compilers, 
which basically require a whole separate install per target.

> The lookup would sue the triple. The lookup order would be triple 
> including environment, triple without environment, os only and 
> default. The first entry matched is used. The config file would look 
> like:
> […]

This looks like a good start. Two ideas:
  - What format do you want to use for the config file? libconfig, like 
we are doing right now? (I didn't know what to make of the missing 
quotes in your example.)

  - Do more specific keys always completely override what a more general 
configuration group might contain? If yes, might there be situations 
where this gets cumbersome? The example I'm thinking about here is a 
possible future druntime version with different "ports" directories for 
the platform specific files, as has been discussed in the past. In this 
case, there might be an additional import path per platform, which 
should just be added to the other list of locations. (The question would 
be whether a facility to address this would be worth the added 
complexity, though…)

Another topic we need to address after this has been finalized is how to 
best integrate cross-compilation into the build process (this mainly 
concerns building druntime/Phobos).

Glad to see progress on this front!

Best,
David