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[SR-13564] ObjectIdentifier's equal has an unexpected result #56002

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swift-ci opened this issue Sep 18, 2020 · 3 comments
Open

[SR-13564] ObjectIdentifier's equal has an unexpected result #56002

swift-ci opened this issue Sep 18, 2020 · 3 comments
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. standard library Area: Standard library umbrella

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@swift-ci
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Previous ID SR-13564
Radar rdar://problem/69169351
Original Reporter 酷酷的哀殿 (JIRA User)
Type Bug

Attachment: Download

Additional Detail from JIRA
Votes 0
Component/s Standard Library
Labels Bug
Assignee None
Priority Medium

md5: b66954dda298d0c551eb157c90071d53

Issue Description:

//代码占位符
    func makeIdentifier(input: Int) -> ObjectIdentifier {
        ObjectIdentifier(NSNumber(value:input));
    }
    
    let a = makeIdentifier(input: Int.min);
    let b = makeIdentifier(input: Int.max);
    print(a == b) // print: true

we expected it is false

Reason:

The first IntegerRef will be free after ObjectIdentifier.init, so the second will use the same heap memory.
@typesanitizer
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@swift-ci
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Comment by Kyle Macomber (JIRA)

We should document that ObjectIdentifier are only unique while the object is alive.

@lorentey
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ObjectIdentifier is only guaranteed unique as long as the underlying object exists – when the instance gets deallocated, its object identifier may be reused for a different object. (Internally, objects are identified by their memory location.)

This works as intended, although the documentation ought to describe this fact.

@swift-ci swift-ci transferred this issue from apple/swift-issues Apr 25, 2022
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bug A deviation from expected or documented behavior. Also: expected but undesirable behavior. standard library Area: Standard library umbrella
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@lorentey @typesanitizer @swift-ci