[Foundation] Fix Data.count’s setter #28919
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Data provides a settable `count` property. Its expected behavior is undocumented, but based on the implementation, it is intended to zero-extend (or truncate) the collection to the specified length. This does not work correctly if we start with an empty Data and we try to increase the count by a small integer: ``` import Foundation var d = Data() d.count = 2 print(d.count) // ⟹ 0⁉️ d.count = 100 print(d.count) // ⟹ 100 ✓ ``` It looks like this bug was introduced with the Data overhaul that shipped in Swift 5. (This issue was uncovered by swiftlang#28918.) rdar://58134026
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@swift-ci test |
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Looks good to me. Good catch: thanks! |
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This probably should also be applied to sclf too |
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Merging. It looks like corelibs-Foundation indeed has the same issue -- I'll submit a patch in a jiffy. |
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Dataprovides a settablecountproperty. Its expected behavior is undocumented, but based on the implementation, it is intended to zero-extend (or truncate) the collection to the specified length.This does not work correctly if we start with an empty
Dataand we try to increase the count by a small integer:It looks like this bug was introduced with the
Dataoverhaul that shipped in Swift 5.(This issue was uncovered by #28918.)
rdar://58134026