How do closures infer their type based on the trait they’re required to implement?

It seems to be a glitch. The Rust-analyzer LSP is able to infer what the type is supposed to be, but for whatever reason the compiler can’t.

From what I can tell, this code doesn’t compile on any version of Rust, and cannot be automatically fixed with cargo fix.

Interestingly, the compiler does seem to work on this equivalent code:

bar(|x| x ^ true);