[D-runtime] Why does druntime us .di files instead of .d?

[Walter Bright]

On 7/13/2011 2:21 PM, Jonathan M Davis wrote:
> On 2011-07-13 13:36, Walter Bright wrote:
>> .di files are used when they are generated from .d files.
> Yes. I get that. But why are .di files generated in the first place?

To 1. hide implementation details and 2. speed up compilation.

>   Phobos just uses .d files.

It'll eventually migrate to .di files.

>   It doesn't generate any .di files. druntime, on the other
> hand, generates .di files, and that's what you end up importing when you
> import core.*. I don't understand why the .di files are being used at all.
>