[lldb] Return the correct utility function in AppleObjCRuntimeV2

[JDevlieghere]

Summary

A copy/paste error in GetClassInfoUtilityFunction resulted in the wrong
utility function being returned: copyRealizedClassList instead of
getRealizedClassList_trylock.

[aprantl]

Oh boy, these are scary. Should LLDB fail harder when the utility expression fails, so we can detect these earlier?

[JDevlieghere]

In D128378#3602888, @aprantl wrote:

Oh boy, these are scary. Should LLDB fail harder when the utility expression fails, so we can detect these earlier?

Fortunately we print an error, but we're also pretty resilient against some of this information missing. This bug was particularly tricky because it only causes a problem the second time that you execute the utility function, which only occurs when you have lazily instantiated classes (in Swift) which is why we didn't see this on llvm.org

lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp

if (!m_objc_copyRealizedClassList_helper.utility_function)
       m_objc_copyRealizedClassList_helper.utility_function =
           GetClassInfoUtilityFunctionImpl(exe_ctx, helper,
                                           g_get_dynamic_class_info2_body,
                                           g_get_dynamic_class_info2_name);
     return m_objc_copyRealizedClassList_helper.utility_function.get();
   }
   case objc_getRealizedClassList_trylock: {
     if (!m_objc_getRealizedClassList_trylock_helper.utility_function)
-      m_objc_copyRealizedClassList_helper.utility_function =
+      m_objc_getRealizedClassList_trylock_helper.utility_function =
           GetClassInfoUtilityFunctionImpl(exe_ctx, helper,
                                           g_get_dynamic_class_info3_body,
                                           g_get_dynamic_class_info3_name);
-    return m_objc_copyRealizedClassList_helper.utility_function.get();
+    return m_objc_getRealizedClassList_trylock_helper.utility_function.get();
   }
   }
   llvm_unreachable("Unexpected helper");
 }
 
 lldb::addr_t &
 AppleObjCRuntimeV2::DynamicClassInfoExtractor::GetClassInfoArgs(Helper helper) {
   switch (helper) {