So did we ever start the effort to extract diagnostic handling into a library? (cc @Esteban Küber) If so, what is the library name?
But there may be more than that, not sure. @nikomatsakis ^
That's it but work on it has been sparse, other than getting it into the repo
the current integration of the library with rust is living here: https://github.com/rust-lang/rust/blob/master/src/librustc_errors/annotate_snippet_emitter_writer.rs
with some (but not all) remaining issues here: https://github.com/rust-lang/rust/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc+annotate-snippet+emitter