No clang diagnostic pragmas, the only trick is stuffing NSAutoreleasePool into a local to avoid the deprecation-under-ARC warning.

gistfile1.m

// Built for ARC, remove the __bridge and it should work in MRC as well.
void *NNCFAutorelease(CFTypeRef cfObject)
{
    if (cfObject) {
        static Class arp = Nil;
        static dispatch_once_t onceToken;
        dispatch_once(&onceToken, ^{
            arp = NSClassFromString(@"NSAutoreleasePool");
            Assert(arp);
        });
        
        [arp addObject:(__bridge id)cfObject];
    }
    
    return (void *)cfObject;
}