Unrecognized syntax in sample code

[Steve Frysinger]

I did a bunch of C++ programming back in the 1980s and early 90s, but not much since. In trying to program a CoreAudio application, about 10 years ago I found the sample below, and was able to use and compile it. But now it won't compile, complaining about the undeclared identifier "home". This seems to be some sort of a "go to" tag with which I'm not familiar. I guess it was legal 10 years ago but it's not now, and I don't even know what name to call it so that I can search for help about it. In the code below, it looks like the function require_noerr executes another function and, if there's an error, it jumps to the "home" tag at the end. Can anyone shed light on this construct? Is there a way to make this work? (And yes, I'm flying blind with CoreAudio just trying to make something simple work...)

 OSStatus PathToFSSpec ( const char *filename, FSSpec &outSpec )
{
  FSRef fsRef;
  OSStatus result;
  require_noerr ( result = FSPathMakeRef ((const UInt8*)filename, &fsRef, 0), home );
  require_noerr ( result = FSGetCatalogInfo (&fsRef, kFSCatInfoNone, NULL, NULL, &outSpec, NULL), home );

  home: return result;
}

[Ganado]

It's a label, which is used with goto.
Generally, the use of goto is considered a bad practice, although I have seen it in places where there's a lot of branching paths, but some sort of cleanup that needs to happen before a function returns.

The require_noerr basically has to be a macro for this to compile, because a label cannot be a function parameter.

If you search the web for require_noerr, you'll find similar issues people have had. Apparently, the require_noerr macro has changed for newer Apple systems, and has broken backwards compatibility.

See: https://stackoverflow.com/questions/46221364/xcode-9-throws-errors-involving-require
You need to change require_noerr to __Require_noErr.

[Steve Frysinger]

Thanks! Yes, I'm old enough to have read "Goto considered harmful", so I was surprised that this looked like that. I guess this is an alternative to the use of "break" to get to a recovery point. I did find that the "standard" syntax of changed, as you mention, and I was able to get this old code to compile by editing to include the leading spaces. Many thanks!