Oh, another random thing that may figure into proc macro APIs: what about the general desire for “collector” macros, that is, some kind of facility for aggregating info from annotated items and feeding that into another macro (see pre-rfc, and RFC 2318 proposes a restricted step in the same direction). This can be useful for things like test harnesses to grab all the tests, or web frameworks to grab all the routes, etc. You can currently hack this in with global variables in the proc macro crate and careful ordering of macro invocations, but that’s obviously brittle and doesn’t work at all in the presence of incremental compilation. Is there a solution for this use-case on the horizon?