[swift-evolution] Enhancing access levels without breaking changes

[Chris Lattner]

On Apr 11, 2017, at 10:30 PM, David Hart <david at hartbit.com> wrote:
>> To me, the reason for limiting it to a file is about predictability, the ability to locally reason about a type, and the need to define some boundary (for symbol visibility reasons).  Saying that extensions to a type have access to private members if they are in the same module is just as arbitrary as limiting it to a single file, and a whole lot less useful from the “reasoning about a type” perspective.
> 
> I think you misunderstand. We were talking about two extensions of a type, in a different file from the type, to share private members between themselves.
> 
> Doug Gregor mentioned it during the PR process and we added an example to disallow it, but in hindsight, I think it should be allowed.

Ah, you’re saying:

a.swift:
struct X {}

b.swift:
extension X {
  private func f() {}
}

extension X {
  func g() { f() }
}

If so, then yes, I agree we should accept that.

-Chris







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