tests/ui/traits/impl-for-module.rs - toolchain/rustc - Git at Google

 mod a {
 }

 trait A {
 }

 impl A for a { //~ ERROR expected type, found module
 }

 fn main() {
 }
	mod a {
	}

	trait A {
	}

	impl A for a { //~ ERROR expected type, found module
	}

	fn main() {
	}