[ObjectiveC] Make NSObject.hashValue non-overridable #20129
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We deprecated overriding it in 4.2 with a custom compiler warning. This removes the ability to override it entirely. The correct way to customize hashing for NSObject subclasses is to override the `hash` property.
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@swift-ci please test |
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@swift-ci please test source compatibility |
parkera
reviewed
Oct 29, 2018
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| override func hash(into hasher: inout Hasher) { // expected-error {{overriding non-open instance method outside of its defining module}} expected-error {{overriding declarations in extensions is not supported}} | ||
| } | ||
| } |
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Maybe something here should show the correct way to override hash?
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Agreed! The warning we have in 4.2 is extremely helpful. I have a pending task to improve error diagnostics -- it's not ABI impacting though.
warning: override of 'NSObject.hashValue' is deprecated; override 'NSObject.hash' to get consistent hashing behavior
airspeedswift
approved these changes
Oct 29, 2018
parkera
approved these changes
Oct 29, 2018
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@swift-ci please test source compatibility |
DougGregor
approved these changes
Oct 30, 2018
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Luckily, the ReactiveCocoa/ReactiveSwift failures seem unrelated. |
This was referenced Jan 24, 2019
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Swift 4.2 deprecated overriding
NSObject.hashValue, by way of a custom compiler warning. This PR removes the ability to override it entirely.The correct way to customize hashing for
NSObjectsubclasses is to override thehashproperty. Classes that overridehashValueinstead breakNSObjectexpectations, and will not work correctly in Foundation'sNSSet,NSDictionaryand similar hashed collections.Note: This PR does not remove the compiler warning, as swift-corelibs-foundation still defines
NSObject.hashValueas open.rdar://problem/42623458