Some confusion about inferred type signature of closures

[alice]

Honestly, the compiler is just being kinda stupid with this issue.

See also:

Rust Quiz 5: when will higher-ranked closure type be yielded?

https://dtolnay.github.io/rust-quiz/5 Here is the code: trait Trait { fn p(self); } impl<T> Trait for fn(T) { fn p(self) { print!("1"); } } impl<T> Trait for fn(&T) { fn p(self) { print!("2"); } } fn f(_: u8) {} fn g(_: &u8) {} fn main() { let a: fn(_) = f; let b: fn(_) = g; let c: fn(&_) = g; a.p(); // 1 b.p(); // 1 c.p(); // 2 } I'm kind of confused about the output of c.p(). According to the revelation: For b we infer _ =…