Extend the lifetime of the buffer while copying from a _CocoaArrayWrapper

[DougGregor]

Thanks to @atrick for finding the issue

Fixes rdar://90108215.

[DougGregor]

@swift-ci swift please smoke test

[DougGregor]

@swift-ci please smoke test

[atrick]

LGTM. It's reasonable to keep the source array alive until the method is done accessing the copied elements. I'm guessing the array might be copied to itself. Actually, any call to NSArray.getObjects needs to be guarded by something that forces the array to be alive as long as the copied array contents are accessed.

Adding the withExtendedLifetime here is definitely harmless.

[atrick]

@lorentey Heads up for any calls to NSArray/NSDictionary getObjects. It copies into a C array without retaining the elements so we need to manually keep the original container alive.

[lorentey]

🙀 Wow, thanks for catching this!

I would've probably looked at this for hours, assuming self was kept alive, and completely missing that this is a __consuming method.