LYR-SEM0235

a member two seen modules add

error · spec 04-modules

A call names a member that two modules this one sees add to the type, each in an extend block, at a count both take.

Explanation

An extend block in a module other than its type's adds members where that module is imported — directly, or through a pub import that passes it on. Where two such modules are seen and both add the name, a call cannot tell which is meant, and taking one would depend on the order of the imports.

Import only the module whose member is meant, or rename one of the two.

Wrong

//- src/loud.lyr
pub extend string {
    pub fn shout(): string {
        return this + "!";
    }
}
//- src/soft.lyr
pub extend string {
    pub fn shout(): string {
        return this + "?";
    }
}
//- src/main.lyr
import app.loud;
import app.soft;

fn main(): void {
    let _ = "hey".shout();
}

Right

//- src/loud.lyr
pub extend string {
    pub fn shout(): string {
        return this + "!";
    }
}
//- src/soft.lyr
pub extend string {
    pub fn shout(): string {
        return this + "?";
    }
}
//- src/main.lyr
import app.loud;

fn main(): void {
    let _ = "hey".shout();
}