How do you handle 'require( ..., bail)' statements with ARC?

Question

I'm looking through some of the sample code for the Square Cam in Apple's sample code. I want to replicate some of it's functionality in a modern project using ARC. However, there are a ton of require statements such as:

BOOL success = (destination != NULL);
require(success, bail);

Which generates the compiler error:

Goto into protected scope.

My question is -- what is the appropriate way to handle such statements in a project using ARC?

Answer 1

I had the same problem (with the same sample code). The code looked like this:

BOOL success = (destination != NULL);
require(success, bail);

//Initialise some variables

bail:
//Deal with errors

I added braces around the block with the declarations to make their scope clear:

BOOL success = (destination != NULL);
require(success, bail);
{
    // *** Initialise some variables ***
}
bail:
{
    //Deal with errors
}

And it solved the problem for me. Through looking at this I also learned you can sometimes expand build errors to get more detail.

Answer 2

Apparently bail is in a scope with one or more __block variables; this is not allowed. See http://clang.llvm.org/compatibility.html#blocks-in-protected-scope for more. The solution proposed there is to limit the scope of the __block variable(s), by putting them in brace-delimited blocks. This may not work always; YMMV.