[swift-evolution] [Proposal] Allow upgrading weak self to strong self by assignment

[Evan Maloney]

> On Feb 19, 2016, at 8:40 PM, Andrew Bennett via swift-evolution <swift-evolution at swift.org> wrote:
> 
> A quick note, I'm not sure if it's a hack but you can probably still do this:
> 
>    guard let `self` = self else { return }

IIRC, the fact that this works is accidental and Chris Lattner mentioned that it should be considered a bug.