[SR-2371] Run-time crash in ObjC code accessing date added to NSMutableDictionary by Swift code

[swift-ci]

Previous ID	SR-2371
Radar	rdar:///27875914
Original Reporter	curt (JIRA User)
Type	Bug

Attachment: Download

Environment

Xcode 8b6

Additional Detail from JIRA

Votes	0
Component/s	Compiler
Labels	Bug, RunTimeCrash
Assignee	None
Priority	Medium

md5: 277dd98cf382487b488e4fb3c9d336e4

Issue Description:

1. In the attached code, an NSMutableDictionary instance is created in an Obj-C method, +[OldSchool dictionary], that is called by Swift code, NewSchool.getDict().

The Swift code updates the dictionary to map a String to a Date, then attempts to pass that dictionary back to a C function, stringValueFromDictionary(), that expects an NSDictionary.

The compiler in Xcode 8b6 surfaces the C function as taking an argument of type [AnyHashable: Any], per #116. To provide the right type, we copy the NSMutableDictionary instance and cast it to [AnyHashable: Any].

In the implementation of stringValueFromDictionary(), we retrieve the date from the dictionary, expecting it to be an NSDate object. Calling any NSDate method on the value crashes.

Steps to Reproduce:

Compile and run the attached project.

Expected Results:

The bridging of the [AnyHashable: Any] value in Swift back to NSDictionary in C should bridge the Date object to NSDate.

Actual Results:

Crash:

2016-08-16 15:51:25.232 AnyWhatNow[62058:772408] -[_SwiftValue dateByAddingTimeInterval:]: unrecognized selector sent to instance 0x100d02420
2016-08-16 15:51:25.234 AnyWhatNow[62058:772408] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[_SwiftValue dateByAddingTimeInterval:]: unrecognized selector sent to instance 0x100d02420'

• • • First throw call stack:
      (
      0 CoreFoundation 0x00007fff8a6064f2 __exceptionPreprocess + 178
      1 libobjc.A.dylib 0x00007fff916c8f7e objc_exception_throw + 48
      2 CoreFoundation 0x00007fff8a6701ad -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
      3 CoreFoundation 0x00007fff8a576571 _forwarding_ + 1009
      4 CoreFoundation 0x00007fff8a5760f8 _CF_forwarding_prep_0 + 120
      5 AnyWhatNow 0x0000000100001f5b stringValueFromDictionary + 91
      6 AnyWhatNow 0x000000010000228d _TFC10AnyWhatlibc++abi.dylib: terminating with uncaught exception of type NSException

Notes:

It's entirely possible that I'm just "holding it wrong", but I've found no way to insert an date object into a dictionary in Swift and successfully make that date usable in Objective-C code that receives the dictionary.

[swift-ci]

Comment by Curt Clifton (JIRA)

Replacing the Date instance in the code with a literal string and trying to call an NSString method on it in the ObjectiveC code crashes in the same way. It appears that the problem is with the boxing, as the value type appears to be a "Swift.Optional<Any>" in the debugger:

(lldb) p (char *)swift_getTypeName((void *)[date _swiftTypeMetadata], 1)
(char *) $2 = 0x0000000100b03920 "Swift.Optional<Any>"

I'm not sure where the optionality is coming from, except in the boxing.

[jckarter]

Trying a fix: #4339

[swift-ci]

Comment by Curt Clifton (JIRA)

Replacing:

d["date"] = Date()

with:

d.setObject(Date(), forKey: "date" as NSString)

in NewSchool.getDict() works around the problem.