use query_group_macro::query_group; #[query_group] pub trait ArityDb: salsa::Database { fn one(&self, a: ()) -> String; fn two(&self, a: (), b: ()) -> String; fn three(&self, a: (), b: (), c: ()) -> String; fn none(&self) -> String; } fn one(_db: &dyn ArityDb, _a: ()) -> String { String::new() } fn two(_db: &dyn ArityDb, _a: (), _b: ()) -> String { String::new() } fn three(_db: &dyn ArityDb, _a: (), _b: (), _c: ()) -> String { String::new() } fn none(_db: &dyn ArityDb) -> String { String::new() }