tests/ui/macros/issue-30007.rs - third_party/github.com/rust-lang/rust - Git at Google

 macro_rules! t {
     () => ( String ; );     //~ ERROR macro expansion ignores token `;`
 }

 fn main() {
     let i: Vec<t!()>;
 }
	macro_rules! t {
	() => ( String ; ); //~ ERROR macro expansion ignores token `;`
	}

	fn main() {
	let i: Vec<t!()>;
	}