What are (were) the most difficult parts of D?

[Christopher Katko]

Is there any way we can get numbered errors like C++ / Microsoft 
have?

  E2040 Declaration terminated incorrectly

Because then we could easily have a wiki for common error cases 
with code snippets of it occurring, and a fix for it. Common 
triggers of this error vs the proper code.

And a neat feature that Allegro.cc does, it automatically scans 
forum posts for usages of Allegro functions (e.g. 
al_draw_bitmap() man page will include links to posts that ask 
about al_draw_bitmap and has a Yes/No question next to it "was 
this a helpful post" so you can remove bad matches). Here it 
would be even easier than matching random questions because error 
codes are specific string literals ("E2040") and not some sort of 
regex attempt to match someone asking a question about 'R[][][] 
datatypes' or something like that.

Here is an example:

https://www.allegro.cc/manual/5/al_draw_bitmap

and an C++ error page:

https://docwiki.embarcadero.com/RADStudio/Sydney/en/E2040_Declaration_terminated_incorrectly_(C%2B%2B)