src/test/ui/unsafe/unsafe-fn-used-as-value.rs - third_party/rust - Git at Google

 unsafe fn f() { return; }

 fn main() {
     let x = f;
     x();    //~ ERROR call to unsafe function is unsafe
 }
	unsafe fn f() { return; }

	fn main() {
	let x = f;
	x(); //~ ERROR call to unsafe function is unsafe
	}