tests/ui/cast/unsupported-cast.rs - toolchain/rustc - Git at Google

 struct A;

 fn main() {
   println!("{:?}", 1.0 as *const A); //~ERROR  casting `f64` as `*const A` is invalid
 }
	struct A;

	fn main() {
	println!("{:?}", 1.0 as const A); //~ERROR casting `f64` as `const A` is invalid
	}