type <MODULE>::<STRUCT> does not implement any method in scope named <METHOD>

[Calamari]

Hello. I am not quite sure, if this is a bug, or I misunderstood something, but to me it looks wrong that I get the following error:

~/work/rusty/traits/src/main.rs:7:36: 7:43 error: type `traits::Point` does not implement any method in scope named `sub`
~/work/rusty/traits/src/main.rs:7   println!("p1-p2= x:{}, y:{}", p1.sub(p2).x, p1.sub(p2).y);
                                                                                   ^~~~~~~
~/work/rusty/traits/src/main.rs:7:50: 7:57 error: type `traits::Point` does not implement any method in scope named `sub`
~/work/rusty/traits/src/main.rs:7   println!("p1-p2= x:{}, y:{}", p1.sub(p2).x, p1.sub(p2).y);

Within this code:

fn main() {
  let p1 = traits::Point { x: 1, y: 1 };
  let p2 = traits::Point { x: 1, y: 1 };
  println!("p1+p2= x:{}, y:{}", p1.add(p2).x, p1.add(p2).y);
  println!("p1-p2= x:{}, y:{}", p1.sub(p2).x, p1.sub(p2).y);
}

mod traits {
  pub struct Point {
    pub x: int,
    pub y: int,
  }

  trait Subtract {
    pub fn sub(&self, p: Point) -> Point;
  }

  impl Point {
    pub fn add(&self, p: Point) -> Point {
      Point {
        x: self.x + p.x,
        y: self.y + p.y,
      }
    }
  }

  impl Subtract for Point {
    pub fn sub(&self, p: Point) -> Point {
      Point {
        x: self.x - p.x,
        y: self.y - p.y,
      }
    }
  }
}

While this code (same, but without the module definition) compiles and works perfectly:

//extern crate traits;

fn main() {
  let p1 = Point { x: 1, y: 1 };
  let p2 = Point { x: 1, y: 1 };
  println!("p1+p2= x:{}, y:{}", p1.add(p2).x, p1.add(p2).y);
  println!("p1-p2= x:{}, y:{}", p1.sub(p2).x, p1.sub(p2).y);
}

//mod traits {
  struct Point {
    x: int,
    y: int,
  }

  trait Subtract {
    fn sub(&self, p: Point) -> Point;
  }

  impl Point {
    fn add(&self, p: Point) -> Point {
      Point {
        x: self.x + p.x,
        y: self.y + p.y,
      }
    }
  }

  impl Subtract for Point {
    fn sub(&self, p: Point) -> Point {
      Point {
        x: self.x - p.x,
        y: self.y - p.y,
      }
    }
  }
//}

Is it a bug, or what am I doing wrong?

[Calamari]

Ah, Understood.
I missed a use traits::Subtract; statement.