llvm-project/clang/test/SemaObjC/va-method-1.m

// RUN: clang -cc1 -fsyntax-only -verify %s

#include <stdarg.h>

@interface NSObject @end
@interface XX : NSObject @end

@implementation XX
- (void)encodeValuesOfObjCTypes:(const char *)types, ... {
   va_list ap;
   va_start(ap, types); 
   while (*types) ;
   va_end(ap);
}

@end