Name resolution for lifetimes: type declarations.
Maps the id of each lifetime reference to the lifetime decl that it corresponds to.
The origin of a named lifetime definition.
This is used in diagnostics to improve suggestions for missing generic arguments.
It gives information on the type of lifetimes that are in scope for a particular
so that we can e.g. suggest elided-lifetimes-in-paths of the form <’, ’> e.g.
A set containing, at most, one known element.
If two distinct values are inserted into a set, then it
Many, which can be used to detect ambiguities.