Re: NSInvocation crashes in AutoreleasePool
Re: NSInvocation crashes in AutoreleasePool
- Subject: Re: NSInvocation crashes in AutoreleasePool
- From: "Gerriet M. Denkmann" <email@hidden>
- Date: Thu, 23 Oct 2014 00:46:30 +0700
> On 22 Oct 2014, at 03:17, Greg Parker <email@hidden> wrote:
>
>
>> On Oct 21, 2014, at 2:44 AM, Gerriet M. Denkmann <email@hidden> wrote:
>>
>> 10.10, Xcode 6.1, using Arc.
>>
>> The following code works fine, with USE_INVOCATION defined or not:
>
> [...]
>
>> Without USE_INVOCATION defined, I get some compiler warning about potential leaks, because selector is unknown.
>>
>> But with USE_INVOCATION defined, it will crash later (when all has been done), obviously while cleaning an AutoreleasePool:
>
> [...]
>
>> Seems like Arc (or I) is somehow confused.
>>
>> Any help would be greatly appreciated.
>
> Start with the Allocations instrument. It will show you the retain/release history of the dead object.
>
> (My guess is that the bug is the call to -getReturnValue:. That method simply copies the return value's bytes into the destination variable, but ARC thinks the destination variable stores a retained pointer. The Allocations instrument should show that the returned object is the one that is used after deallocation.)
I tried (with zombies on):
[ invocation invoke ];
NSDictionary *a;
[ invocation getReturnValue: &a ];
NSLog(@"%s got new %p",__FUNCTION__, a);
Result:
...
got new 0x6100004475c0
*** -[__NSDictionaryM release]: message sent to deallocated instance 0x6100004475c0
This seems to prove your guess that " the bug is the call to -getReturnValue:".
But how to fix this?
Kind regards,
Gerriet.
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