tests/ui/mut/mut-cross-borrowing.rs - rust-lang/rust - Git at Google

 fn f(_: &mut isize) {}

 fn main() {

     let mut x: Box<_> = Box::new(3);

     f(x)    //~ ERROR mismatched types
 }
	fn f(_: &mut isize) {}

	fn main() {

	let mut x: Box<_> = Box::new(3);

	f(x) //~ ERROR mismatched types
	}