DMD Symbol Reference Analysis Pass

[via Digitalmars-d-learn]

Does DMD currently do any analysis of references to a symbol in a 
given scope? If not where could this information be extracted (in 
which visitor/callback) and in what structure should it, if so, 
be stored?

Reason: After having read about Rust's data-flow (and in turn 
escape) analysis I'm very curious about how difficult it would be 
to add more clever type inference, of for example symbol 
mutability, based on this analysis.

I'm asking again because of the work recently done in DIP-25, 
that may be related to this problem.