Open Radar

 
This crash is only reproducible on iOS 10 when building with Xcode 8 or 8.1.

Summary:
Given a function or method with an NSError** handle as a parameter:
void __VIPErrorHandleBrokenTestFunction(NSError **error)
{
	NSBlockOperation *operation  = [NSBlockOperation blockOperationWithBlock:^{
		if (error) {
			*error = [[NSError alloc] initWithDomain:@"VIPTesting" code:-123 userInfo:@{}];
		}
	}];
	NSOperationQueue *queue = [[NSOperationQueue alloc] init];
	[queue addOperations:@[operation] waitUntilFinished:YES];
}

If I de-reference that error and assign it within a block the compiler will produce crashing code and not flag this as an error or warning.

Steps to Reproduce:
1. Set xcodebuild to use the Xcode 8 toolchain.
2. Compile the attached file in terminal with: `clang -fobjc-arc -framework Foundation NSErrorCrash.m -o NSErrorCrash`
3. Run the compiled executable in terminal with: `./NSErrorCrash `


Expected Results:
Compiler should emit an error or warning indicating that the syntax is wrong and that the inner *error de-reference is going to cause a crash because it is assigning a pointer that is nor marked as __block.

Actual Results:
No warnings/errors are emitted by the compiler. Executable crashes at runtime.

Version:
Xcode 8 and 8.1 all GM versions. Have not tested on Xcode 8 betas.

Notes:


Configuration:


Attachments:
'NSErrorCrash.m' was successfully uploaded.

```
#import <Foundation/Foundation.h>

void __VIPErrorHandleBrokenTestFunction(NSError * __autoreleasing *error)
{
	NSBlockOperation *operation  = [NSBlockOperation blockOperationWithBlock:^{
		if (error) {
			*error = [[NSError alloc] initWithDomain:@"VIPTesting" code:-123 userInfo:@{}];
		}
	}];
	NSOperationQueue *queue = [[NSOperationQueue alloc] init];
	[queue addOperations:@[operation] waitUntilFinished:YES];
}

void __VIPTestBlockCrashOnIOS10BuiltWithXcode8(void)
{
	for (int i = 0; i < 10; i++) {
		NSError *error;
		__VIPErrorHandleBrokenTestFunction(&error);
		//NSLog(@"Error: %@", error);
	}
}


int main(int argc, char *argv[]) {
	@autoreleasepool {
		__VIPTestBlockCrashOnIOS10BuiltWithXcode8();
		
		[[NSRunLoop mainRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:5.0]];
		NSLog(@"iOS X autorelease crash bug is fixed!");
	}
}
```