[swift-evolution] Allow protocol vars to match derived types

[Mark Anders]

Thanks Joe, bug submitted!

Mark

On March 8, 2016 at 2:27:57 PM, Joe Groff (jgroff at apple.com) wrote:


On Mar 8, 2016, at 1:15 PM, Mark Anders via swift-evolution <swift-evolution at swift.org> wrote:

Slava/Joe, thanks for clarifying the issue and Slava for providing more depth on what needs to happen. Like David, I was unsure if this was just a bug or an enhancement.

Out of curiosity, you mention some related issues, and I just ran into something similar and wonder if it’s related too.

class A {}
class B : A {}

var arrayOfA = [A]()
let arrayOfB : [B] = [B()]
arrayOfA.appendContentsOf(arrayOfB)

This fails to compile, though doing arrayOfA.append(B()) works as I would expect.

This one seems like a plain bug to me, since it should be possible to convert arrayOfB to [A] and hand the [A] off to appendContentsOf.

-Joe
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