tests/ui/parser/issue-116781.rs - rust-lang/rust - Git at Google

 #[derive(Debug)]
 struct Foo {
     #[cfg(true)]
     field: fn(($),), //~ ERROR expected pattern, found `$`
     //~^ ERROR expected pattern, found `$`
 }

 fn main() {}
	#[derive(Debug)]
	struct Foo {
	#[cfg(true)]
	field: fn(($),), //~ ERROR expected pattern, found `$`
	//~^ ERROR expected pattern, found `$`
	}

	fn main() {}