Are there any examples of macros or compiler plugins that have access to type information?
Some of clippy's lints run after type checking passes: GitHub - Manishearth/rust-clippy: A bunch of lints to catch common mistakes and improve your Rust code
Plugins that modify the AST will always run before type checking, though.
Hm, wasn't there some talk about having plugins modify AST and have access to type information?
Rust does not do type checking on the AST I believe. I think type checking is done on HIR, and borrow checking is/will soon be done even later (on MIR).
Yeh, I think this is a bit of a gap in what compiler plugins can do.
The best I've been able to do is build plugins in such a way that the emitted code can call out to methods that infer the type and do something based on that.