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

[swift-ci]

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]

@swift-ci create

[swift-ci]

Comment by Kyle Macomber (JIRA)

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

[lorentey]

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.