Function disambiguate 

fn disambiguate(
    collected: BTreeMap<String, BTreeSet<(Kind, String)>>,
) -> BTreeMap<String, String>

Flattens a multimap into the map the file carries.

A key with one item keeps its bare spelling. A key with several gets one entry per item under rustdoc’s own disambiguator syntax (trait@atune::Space) and no bare entry, so a page that names the ambiguous spelling fails in the macro with both alternatives rather than silently linking to whichever item sorted first.