What do you want to see for a mature DLang?

[IM]

I will start:

    -- Better compiler errors, better compiler errors, better 
compiler errors.


I really wish that the compiler errors could receive some 
refinement. Mostly it feels like some error text just being 
thrown at me. It needs to be better formatted, more helpful, with 
suggestions about how to fix (if possible).

To illustrate my point:

- See the compile errors I've just encountered with DMD: 
https://cdn.pbrd.co/images/H0q609l.png

- Now compare that with an error produced by rustc:
https://cdn.pbrd.co/images/H0q6bLi.png


Simple things like these make a big difference. D Lang has been 
around for a long while now, and hence signs of its maturity has 
to show everywhere, especially in the compiler, as well as the 
package manager.