E4046

A public definition cannot depend on private entities.

Erroneous Example

priv trait I {
  m(Self) -> Unit
}

pub impl I for Int with m(self) {
  ignore(self)
}

The above example tries to implement a private trait I for the type Int, but the implementation itself is public, which is not allowed. This gives the following error on line 2:

A public definition cannot depend on private trait

Suggestion

Adjust the visibility of the trait or the implementation to match:

pub(open) trait I {
  m(Self) -> Unit
}

pub impl I for Int with m(self) {
  ignore(self)
}

pub fn call_i(x : Int) -> Unit {
  I::m(x)
}