E4018

Cannot resolve trait for the given type.

Erroneous Example

struct S { v : Int }

let s : S = { v: 3 }
let t = Show::to_string(s)

The example above tries to call the method to_string from the Show trait on a type S, but since S does not implement that trait, it gives the following error on line 4:

Type S does not implement trait Show: method output is missing

Suggestion

Implement the Show trait for the type S:

struct S { v : Int }

let s : S = { v: 3 }
let t = Show::to_string(s)

impl Show for S with output(self, logger) {
  logger.write_object(self.v)
}