[swift-evolution] IUO in Swift 3.0

Chris Lattner clattner at apple.com
Wed Jun 22 15:03:28 CDT 2016

> On Jun 22, 2016, at 8:56 AM, Joe Groff <jgroff at apple.com> wrote:
>> I think that there is some confusion here: it is true that IUO exists internally as a type within the compiler, but the idea of our current implementation is that that is just an implementation detail within the compiler (similar to LValueType, which has no user syntax), not an exposed part of the programmer model.
>> That said, the “T!” *syntax* is intended to stay in Swift.  This is the way to model the IUO declaration modifier, as outlined in the proposal.
> As implemented in the seed, T! still leaks into the user type system.

Are there specific examples of that?  Those examples are bugs, that should be fixed.


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