`#[no_override]` for default methods

Issue by huonw
Monday Jul 08, 2013 at 14:16 GMT

For earlier discussion, see https://github.com/rust-lang/rust/issues/7649

This issue was labelled with: A-attributes, B-RFC in the Rust repository

If there was a #[no_override] attribute that made it impossible to override a default method, there would be very little need for the FooUtil traits (with this attribute default methods would have almost exactly the same properties as *Util, except the seperate trait can be imported separately). i.e.

trait Foo {
  fn bar(&self);

  #[no_override]
  fn call_bar(&self) { self.bar(); }
}
impl Foo for int {
  fn bar(&self) {}

  fn call_bar(&self) {} // error!
}

This would provide a workaround for #5898 that is a proper solution in its own right.

Start by reviewing the earlier discussion in issue #7649 and the workaround context in #5898; this issue names no files, tests, or entry points. Define the attribute's behavior for default methods and the error expected when an implementation overrides one, then verify the proposal against the Rust trait example shown here.