[swift-evolution] SR-104: Improve Crash-Safety when Importing Objective-C Code Without Nullability Attributes

Jordan Rose jordan_rose at apple.com
Fri Dec 11 12:04:39 CST 2015


> On Dec 10, 2015, at 14:28 , Douglas Gregor via swift-evolution <swift-evolution at swift.org> wrote:
> 
>> I noticed there are many constants that get translated to implicitly unwrapped optionals (e.g. in iOS CoreFoundation.swift). Would they be affected by the change in this proposal? Or are they "explicitly set to implicitly unwrapped" by the importer?
> 
> You can grep for “ull_unspecified” in the SDK to find the cases where things are explicitly set to implicitly unwrapped optionals; I doubt there are many.

Please don't forget null_resettable properties, of which there are probably several. Until we have a good answer for Swift here, that's one more reason to keep IUOs.

(The other major feature that uses IUOs is two-phase initialization, like IBOutlets. I don't think we have an answer for that yet either.)

Jordan
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