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mayoff/unowned-safety-dance.swift

Created February 23, 2019 03:00
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test Swift unowned safety
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unowned-safety-dance.swift
class MyObject { }
var o = MyObject()
print("strong o = \(o)")
unowned let u = o
print("unowned u = \(u)")
o = MyObject()
print("new strong o = \(o)")
print("old unowned u = \(u)")
@robertmryan
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robertmryan commented Feb 25, 2019 •
edited

@hamishknight - that was in Swift 4.2.1.

Apple Swift version 4.2.1 (swiftlang-1000.11.42 clang-1000.11.45.1)

@hamishknight
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@robertmryan Ah interesting! Sorry, I missed that part in your original post. Upon re-inspection, you get the same behaviour in 4.2 and 5.0 – it just appears to be sometimes hitting the runtime error and sometimes crashing with EXC_BAD_ACCESS. Digging a bit further, when running with an assert Swift runtime it trips an assertion.

Filed a bug: SR-9999.

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