Generate .di files

[andralex]

Always generate .di files (even if unused for now) so developers can discuss them a la "array.di line 23 in master".

[andralex]

I could measure a degradation of debug build time by less than 5%.

[MartinNowak]

What's the purpose of this?

[kuettler]

I did not know you could do that, it sure is a useful feature. I like it.

[JinShil]

so developers can discuss them a la "array.di line 23 in master".

I don't understand the motivation. Using github, you can currently refer to array.d line 23 (even at a specific commit) in a convenient link.

[quickfur]

I don't understand the motivation either. Why is it necessary for developers to reference line numbers, and how does this PR help? Most of Phobos is templated, meaning the template body gets included in the .di file, so most of the changes checked into Phobos will also change the line numbers in the .di file. So generating .di files doesn't really help retain consistent line numbers either, given the rapid rate at which Phobos changes are merged.

[DmitryOlshansky]

I don't understand the motivation either. Why is it necessary for developers to reference line numbers, and how does this PR help?

Same here and it's looks abandoned.
@andralex OK to close?