[SR-912] Runtime exception casting an Any nil to an Optional. #43524

swift-ci · 2016-03-10T14:59:36Z


Previous ID	SR-912
Radar	None
Original Reporter	astmus (JIRA User)
Type	Bug
Status	Resolved
Resolution	Done

Environment

xcode 7.3 beta 5
os x 10.11.3

Additional Detail from JIRA


Votes	0
Component/s	Standard Library
Labels	Bug, RunTimeCrash, Runtime
Assignee	@atrick
Priority	Medium

md5: dfee632a8b003f40faceb3a233e6d950

Issue Description:

Example

Code below demonstrate type casting of 'Any' object to generic type. Conversion completed successful if optional types have concrete not nil value. If object value equal to nil then conversion to Int32? type by "as!" operator will throw exception.

Code Example

public class Cast<T>
{
    public func printConcrete(obj:Any)
    {
        print(obj as! T)
    }   
    public func printOptional(obj:Any)
    {
        print(obj as? T)
    }
}

let cast = Cast<Int32?>()
var oin : Int32? = 1
cast.printOptional(oin) // Optional(Optional(1))
cast.printConcrete(oin) // Optional(1)
oin = nil
cast.printOptional(oin) // nil
cast.printConcrete(oin) // Could not cast value of type 'Swift.Optional<Swift.Int32>' (0x10f475148) to 'Swift.Int32' (0x105eafd60).

Result for xCode Version 7.2 (7C68) / osX 10.10.5 (14F1509)

as expected code above gave next result

Optional(Optional(1))
Optional(1)
Optional(nil)
nil

belkadan · 2016-03-10T18:22:04Z

@jckarter, any ideas?

jckarter · 2016-03-10T18:24:05Z

@atrick, you fixed this in 7.3, right?

atrick · 2016-03-10T20:01:31Z

I handled the cast of casting Optional -> Optional, but did not handle the case in this example. This case casts an optional boxed within existential to another optional.

My implementation first checks if the source of the cast is optional. If not, it strips the optional from the target and recursively attempts the cast. I thought this was OK because Optional would never directly conform to a protocol. I don't have a better idea here than adding another case to handle Any existentials...

I can try to look at it sometime in the next few days, but any help or suggestions are appreciated.

jckarter · 2016-03-10T20:34:19Z

No rush, just checking to see if this was already fixed.

atrick · 2016-03-23T04:49:34Z

Fixed in
#1799
atrick merged commit 043a85e into apple:master

swift-ci transferred this issue from apple/swift-issues Apr 25, 2022

AnthonyLatsis added the crash Bug: A crash, i.e., an abnormal termination of software label Dec 12, 2022

This issue was closed.

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[SR-912] Runtime exception casting an Any nil to an Optional. #43524

[SR-912] Runtime exception casting an Any nil to an Optional. #43524

swift-ci commented Mar 10, 2016

belkadan commented Mar 10, 2016

jckarter commented Mar 10, 2016

atrick commented Mar 10, 2016

jckarter commented Mar 10, 2016

atrick commented Mar 23, 2016

[SR-912] Runtime exception casting an Any nil to an Optional. #43524

[SR-912] Runtime exception casting an Any nil to an Optional. #43524

Comments

swift-ci commented Mar 10, 2016

Example

Code Example

Result for xCode Version 7.2 (7C68) / osX 10.10.5 (14F1509)

belkadan commented Mar 10, 2016

jckarter commented Mar 10, 2016

atrick commented Mar 10, 2016

jckarter commented Mar 10, 2016

atrick commented Mar 23, 2016