//@ run-pass use std::fmt::Debug; trait InTraitDefnParameters { fn in_parameters(_: impl Debug) -> String; } impl InTraitDefnParameters for () { fn in_parameters(v: impl Debug) -> String { format!("() + {:?}", v) } } fn main() { let s = <() as InTraitDefnParameters>::in_parameters(22); assert_eq!(s, "() + 22"); }