tests/ui/macros/auxiliary/or-pattern.rs - rust-lang/rust - Git at Google

 #![crate_type = "lib"]

 #[macro_export]
 macro_rules! a {
     ($x:pat|) => ();
 }
	#![crate_type = "lib"]

	#[macro_export]
	macro_rules! a {
	($x:pat\|) => ();
	}