@swift-ci create

The best implementation plan I have now is:

1. An AccessScope for a private declaration within an extension is no longer simply its DeclContext. Instead, if the enclosing type is defined in the same file, the type's declaration becomes the AccessScope. Otherwise, the last extension of the type in the file is the AccessScope. This collapses the various extensions in a file into the same AccessScope.

2. When checking if one access scope is contained within another, if the access scope is an extension, look at the base type. If it's defined in the same file, the containing access scope is the private access scope for the base type declaration as described in (1). Otherwise, it's the last extension of the base type in the current file, rather than the file in which it was defined. (If there is no such extension, move up to the next parent.) This allows the example below to compile:

struct Outer {
  struct Middle {
    struct Inner {}
  }
}

extension Outer {
  private static func foo() {}
}

extension Outer.Middle.Inner {
  func bar() {
    Outer.foo()
  }
}

I don't love this because it's a lot of extra work to determine access, but it's the best I have. An invariant here is that a parent access scope never crosses file boundaries, and the three outermost access scopes are still "the current file", "the current module", and "the world".

Ah, I didn't know KingOfBrian (JIRA User) already took this task. Go for it.
FWIW, here's WIP branch of mine.
master...rintaro:ast-accesscope-se-169

Comment by Brian (JIRA)

Thanks @rintaro, things are coming along: – master...KingOfBrian:feature/SE-0169 Should have a PR in tomorrow.

Pull request:

#9098

Merged to `master`.