> On Feb 28, 2017, at 10:39 PM, David Hart <[email protected]> wrote:
>
>>
>> On 28 Feb 2017, at 22:53, Jordan Rose via swift-evolution
>> <[email protected] <mailto:[email protected]>> wrote:
>>
>> Nitpick: 'C<T> & P' is just 'C<T>' in this example. You'd need a refinement
>> of 'P' to make it interesting ('C<T> & Q’).
>
> Could generic specialisation be disallowed in constraints? I need to think
> about this.
I don't think there's any added complexity alone in allowing generic base class
constraints in existentials, since we already support `<T: C<U>>` as a
constraint on a generic parameter. It's the interaction between classes and
protocols with associated types that's interesting. You don't even need a
generic class:
protocol P { associatedtype T; func foo(_: T) }
class C: P { func foo(_: Int) {} }
protocol Q: P {}
let x: C & Q
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