Rustc should at the very least warn you if you export something that doesn't exist.

[eholk]

[brson]

I think it should be an error, but I do have one wrinkle. Currently, tests need to be exported in order to run, so you might have a test module:

mod my {

  export test;

  #[test]
  mod test {
  }
}

When compiled normally, mod test doesn't exist, so it would be an error. I'd like to fix this by giving tests some magic (#721) and not requiring them to be exported. But fwiw, this isn't actually a problem we're running into currently.