[swift-evolution] [Accepted] SE-0169: Improve Interaction Between `private` Declarations and Extensions

[Xiaodi Wu]

On Thu, Apr 20, 2017 at 6:31 PM, Douglas Gregor <dgregor at apple.com> wrote:

>
> On Apr 20, 2017, at 3:39 PM, John McCall <rjmccall at apple.com> wrote:
>
> On Apr 20, 2017, at 6:35 PM, Xiaodi Wu via swift-evolution <
> swift-evolution at swift.org> wrote:
> On Thu, Apr 20, 2017 at 5:03 PM, Douglas Gregor <dgregor at apple.com> wrote:
>
>>
>>
>> On Apr 20, 2017, at 11:33 AM, Jordan Rose <jordan_rose at apple.com> wrote:
>>
>>
>> On Apr 18, 2017, at 20:40, Douglas Gregor via swift-evolution <
>> swift-evolution at swift.org> wrote:
>>
>> This makes the private/fileprivate distinction meaningful for extensions.
>> I think also bans the use of "private" at global scope for non-nominal
>> types or extensions thereof.  A clarifying update to the proposal is in
>> order, so developers can better understand the semantics.
>>
>>
>> Wait, hang on, then people have to write 'fileprivate' instead of
>> 'private' for top-level typealiases (and functions?).
>>
>>
>> That seems like the correct behavior; private is about members with
>> SE-0169. What do you think?
>>
>
> ...that seems suboptimal, given that the goal has been to make it possible
> for people to use `private` more and not less frequently. IMO, there's no
> need for `private typealias` at the global level to be prohibited.
>
>
> Yeah, I see no reason for this to change the behavior of private
> extensions to be more restrictive than before.
>
>
> So you’re okay with:
>
> private extension X {
>   func foo() { }
> }
>
> being equivalent to
>
> extension X {
>   fileprivate func foo() { }
> }
>
> rather than
>
> extension X {
>   private func foo() { }
> }
>
> ?
>
> That seems unintuitive at best.
>

Agree, but the rules for access modifiers in front of extensions have
always been different from those for everything else. Surely, we can
rationalize extensions here as you suggest without having to prohibit
private typealiases.
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