found fn item `extern "rust-intrinsic" fn(_) -> _ {unlikely}`
+ = note: different `fn` items always have unique types, even if their signatures are the same
+ = help: change the expected type to be function pointer `extern "rust-intrinsic" fn(bool) -> bool`
+ = help: if the expected type is due to type inference, cast the expected `fn` to a function pointer: `likely as extern "rust-intrinsic" fn(bool) -> bool`