According to the example from the std::fmt
docs:
extern crate uuid;
use uuid::Uuid;
use std::fmt;
struct BlahLF {
id: Uuid,
}
impl fmt::Debug for BlahLF {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
write!(f, "Hi: {}", self.id)
}
}
The part to emphasize is the fmt::
in fmt::Result
. Without that you’re referring to the plain Result
type. The plain Result
type does have two generic type parameters, fmt::Result
has none.