Re: libobjc2 message-to-nil inconsistency

[Greg Parker]

On May 8, 2012, at 12:24 PM, Jens Alfke wrote:

On May 8, 2012, at 12:19 PM, David Chisnall wrote:

although the old behaviour is still consistent with OS X (return results greater than the size of a pointer are undefined).

I am pretty sure that’s not true anymore, although I am not sure whether I read so in the Apple docs or in comments by Apple runtime engineers on their mailing lists (I have a feeling Greg Parker has brought this up.)

I can say that the exact code I posted before works reliably in 32-bit processes in OS X 10.7 and iOS 5. That’s why I’m only running into this now — I haven’t had any trouble with 64-bit return values until trying to run my code on GNUstep.

OS X and iOS have implemented 64-bit integer return as 0 since time immemorial. 

With current OS and tools, every return type is now zero-filled.

http://www.sealiesoftware.com/blog/archive/2012/2/29/objc_explain_return_value_of_message_to_nil.html

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Greg Parker     gparker@apple.com     Runtime Wrangler