Fix printing of class-constrained protocols [4.0] #11786
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Instead of treating this as its own thing, just parse it as if the user wrote 'AnyObject'.
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@DougGregor Are you OK with taking this for 4.0? The main change is that 'protocol P : class' now parses and prints as 'protocol P : AnyObject'. Since TSPL now only talks about the latter, I think it makes sense to clean up the parser this way. This fix is not quite as narrow as I would like (I originally did it on master and then decided to cherry-pick) but I think we did enough cleanup while implementing subclass existentials that I feel confident in always modeling this as inheritance from AnyObject. |
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@swift-ci Please test |
slavapestov
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Description: In Swift 4.0, we implemented SE-0156, which stipulates that 'protocol P : AnyObject' should be equivalent to 'protocol P : class'. Because of unfortunate representational issues, the generated interface for such a protocol produced ridiculous output like 'protocol P : class, AnyObject where Self : AnyObject'. This PR fixes that and now it just says 'protocol P : AnyObject'.
Scope of the issue: This is just a cosmetic issue, but it was reported by a user on Twitter, who was confused by the redundant constraints. It's also a regression in the sense that we're not asking users to write 'AnyObject' instead of 'class' everywhere, and the new form had this problem.
Tested: New test added to ensure the generated interface looks reasonable.
Risk: Low, I think we tested subclass existentials well enough that folding ': class' into ': AnyObject' in the parser should work as before.
Radar: rdar://problem/34274386
Reviewed by: @DougGregor