message: fix ptr comparison test
diff: -fn f() -> i32 {
  +trait Answer {
  + fn answer() -> Self;
  +}
  +
  +impl Answer for i32 {
  + fn answer() -> i32 {
  42
  }
  +}
  +
  +// A generic function, to make its address unstable
  +fn f<T: Answer>() -> T {
  + Answer::answer()
  +}
  fn g(i: i32) -> i32 {
  i*42
  