[cfe-dev] ARC + goto into protected scope error

[Jordan Rose]

If you put the variable in its own scope, preventing accidental access, you won't get the error:

int main() {
  goto cleanup;
  {
     NSString *str;
  }
cleanup:
  return 0;
}

If you don't do this, you bypass the zero-initialization of 'str', and when ARC tries to clean it up, it'll end up trying to release some random bit of memory.

This should handle any valid case; if you want to use 'goto' but can't enclose the variables in their own scope, you'll have to move the declarations before the goto (as K&R intended *grin*).

Jordan


On Aug 16, 2012, at 18:47 , Dave Keck <davekeck at gmail.com> wrote:

> Hi all,
> 
> I use the "check for success/goto failed" pattern everywhere, but
> Clang refuses to compile such code with ARC enabled if the goto
> bypasses a variable declaration (giving a "goto into protected scope"
> error.)
> 
> Is this something that's likely to be fixed? Compiling the program
> below triggers the error.
> 
>    // compile with: clang -framework Foundation -fobjc-arc <file>.m
>    #import <Foundation/Foundation.h>
>    int main() {
>        goto cleanup;
>        NSString *str;
>        cleanup:
>        return 0;
>    }
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