[Issue 13517] Only touch .di generated file if changed

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=13517

--- Comment #3 from Vladimir Panteleev <thecybershadow at gmail.com> ---
(In reply to Ketmar Dark from comment #1)
> but why compiler should do that? it's a build tool task. the build tool
> should know that .di file is generated from .d and invoke generator only if
> .di file is missing or older than .d.

That idea only applies if you want to do .di generation as a separate compiler
invocation from compilation.

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