LYR-SEM0055

a member that needs a receiver named without one

error · spec 04-modules

A method or field of a type is named bare inside the type (without this.), an instance member is reached through the type, or a static member through a value; a variant is named bare inside its enum.

Explanation

Inside a type's body, its methods and fields are not in scope as bare names: an instance method is called on a value, this.get(), and a field is read as this.x. Through the type name only static members are reached (Point.new()), and through a value only instance members. A variant is written .Leaf or Tree.Leaf.

The rule keeps one way of naming a member, so a bare name always means a local, a parameter or a module-level declaration. Write the receiver, or declare the function static if it needs none.

Wrong

struct Point {
    x: int,
    fn get(): int { return this.x; }
    fn twice(): int { return get() * 2; }
}

fn main(): void {
    let _ = Point { x = 3 }.twice();
}

Right

struct Point {
    x: int,
    fn get(): int { return this.x; }
    fn twice(): int { return this.get() * 2; }
}

fn main(): void {
    let _ = Point { x = 3 }.twice();
}