#![warn(clippy::unit_hash)] use std::collections::hash_map::DefaultHasher; use std::hash::Hash; enum Foo { Empty, WithValue(u8), } fn do_nothing() {} fn main() { let mut state = DefaultHasher::new(); let my_enum = Foo::Empty; match my_enum { Foo::Empty => ().hash(&mut state), Foo::WithValue(x) => x.hash(&mut state), } let res = (); res.hash(&mut state); #[allow(clippy::unit_arg)] do_nothing().hash(&mut state); }