Unresolved import despite explicit `extern mod module;`

[Florob]

An extern mod example; inside another module is apparently ignored:

#[cfg(test)]
mod test {
    extern mod extra;
    use extra::test;
}

test.rs:3:8: 3:13 error: unresolved import. maybe a missing `extern mod extra`?
test.rs:3     use extra::test;
                  ^~~~~
test.rs:3:8: 3:19 error: failed to resolve import `extra::test`
test.rs:3     use extra::test;
                  ^~~~~~~~~~~
error: aborting due to 2 previous errors

[alexcrichton]

This is actually working as intended. As is documented in the manual, all paths referenced from use statements must be crate-relative, not module relative. For code like this to compile, it must be of the form:

#[cfg(test)]         
mod test {           
    extern mod extra;
    use self::extra::test; 
}                    

Arguably the error could be improved upon noticing that the name extra is already in scope of the current module, but it's difficult because of the interdependency of resolving imports at the same time that you're suggesting others.

I'm going to leave this open for now (because the error message can certainly be improved).

[flaper87]

Visiting for triage.

Leaving this open for now. I agree the error message could certainly be better and give the proper hint.

[alexcrichton]

This error message has since greatly improved and now suggested "Did you mean ..." with the appropriate suggestion.