Crash Xcode 14 with Swift -> Objective-C framework; AutoreleasingUnsafeMutablePointer; -O Optimize for Speed

I suspect the optimization may be at fault.

It’s certainly possible, but it’s also possible that something is wonky in the closed source code and the optimiser changes have exposed that.

func listItems() {
    var availableItems: NSMutableArray? = NSMutableArray()
    let result = itemSDK.getAvailableItemList(&availableItems)
   // ...
}

The standard pattern for this is would be to initialise availableItems to nil. Does that help?

The derived Swift interface for this is:

Please post the original C interface for this method.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
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Thanks, eskimo.

I notice another post with a similar issue:.

The header file for the framework had the following protocol...

@protocol itemSDK <NSObject>
- (SDK_RESULT) getAvailableItemList:(NSMutableArray**)itemList;
// ...
@end

I tested this specific API with the "standard pattern" and it does not fail. I will give it a try with the many other SDK interfaces for this framework and see if this can be the best solution. BTW, where is the standard pattern documented as the proper way to pass a value for an AutoreleasingUnsafeMutablePointer?. I found very few examples and most assign an initial value. I reviewed many of the videos from WWDC on unsafe pointers but none cover this particular pointer. Maybe I missed something.

I tested this specific API with the "standard pattern" and it does not fail.

Cool.

BTW, where is the standard pattern documented as the proper way to pass a value for an AutoreleasingUnsafeMutablePointer?.

That’s a good question. I’ve never gone looking for this because the approach I use is ‘obvious’. Most Objective-C code uses this ‘double star’ pattern for out parameters and, if you’re dealing with an out parameter, there’s no point setting up an initial value for it to be overwritten by the callee.

The header file for the framework had the following protocol...

Are there any doc comments, or just docs, that explain the expected calling conventions for this? It certainly looks like itemList is an out parameter but there’s nothing in that prototype that guarantees that [1].

btw I tried reproducing your crash with some test code that replicates the -getAvailableItemList: method but I never got it to crash. That suggests that the problem is somehow tied to the implementation of -getAvailableItemList:, which means it’ll be hard to make progress without cooperation of that code’s author [2].

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

[1] Indeed, the use of NSMutableArray, rather than NSArray, suggests that something else is going on here, but that could just be ignorance on the part of the library’s author. Type names like SDK_RESULT do not inspire me with confidence )-:

[2] Well, in your shoes I’d probably disassemble -getAvailableItemList: to see what it’s actually doing, but that’s definitely above and beyond the call of duty (-:

Again, thanks eskimo.

I tried several other of the APIs using the standard pattern as a solution. This does eliminate crashes but the results returned are not always the same as before when a value was provided instead of nil. In a different, but very similar API call to the getAvailableItemList, an NSMutableArray is to be returned but instead I get a SDK_RESULT value indicating that the invalid parameters have been supplied. If I use the workaround that I have instead (that does crash and provides a non-nil value), then I get a success SDK_RESULT along with the values in the array parameter. So I think each will need to be tested. I just wish I had worked as before without crashing.

I have also tried replicating the same crash with sample Object-C code with no success. Do you know if there might be some interoperbility differences with a framework compiled with an older Xcode but used with Swift code under Xcode 14 (with -O)?. I can try and ask the vendor what Xcode they use to build their frameowrk. Based on the warning in the usage sample code they provide...it is not a recent version.

In a different, but very similar API call to the getAvailableItemList, an NSMutableArray is to be returned but instead I get a SDK_RESULT value indicating that the invalid parameters have been supplied.

Well, that doesn’t exactly inspire me with confidence )-:

Do you know if there might be some interoperbility differences with a framework compiled with an older Xcode but used with Swift code under Xcode 14 (with -O)?

I’m not aware of any systematic problem in this space.

Keep in mind that Swift interacts with a lot of different libraries via the Objective-C ABI. This obviously works in general, otherwise apps would be failing left, right, and centre.

I can try and ask the vendor what Xcode they use to build their frameowrk.

If you do manage to engage with the vendor I recommend that you spend that time clarifying the expected calling conventions for these methods. Don’t muddy the waters by mentioning Swift; just ask ’em how you’re supposed to call these methods from Objective-C.

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"