Why is it that no one writes with portability in mind in druntime?

[Joseph Rushton Wakeling]

On 25/11/13 13:28, qznc wrote:
> The gold standard: Every pull request (or every commit) should be tested with
> DMD/LDC/GDC on x86/amd64/arm with Linux/Win/OSX. That is already 27 variants.
> Actually there should probably be more like with/without SSE.

You have a challenge that (AFAIK, as things are) patches to the frontend can't 
be automatically guaranteed to apply cleanly to GDC and LDC as well as DMD.  And 
given that druntime and phobos patches can depend on frontend features, there's 
some difficulty in being able to automatically test patches to any part of the D 
core code against all the backends.