rust???

busted.rs

enum IResult<I = u32, E = u32> {
  Done(I),
  Error(E)
}

fn main() {
  IResult::Done(0);
}

invocation.sh

rustc busted.rs
error[E0282]: unable to infer enough type information about `E`
 --> busted.rs:7:2
  |
7 |     IResult::Done(0);
  |     ^^^^^^^^^^^^^ cannot infer type for `E`
  |
  = note: type annotations or generic parameter binding required

error: aborting due to previous error