Compile Error

Development Programming & Scripting C++
1

I’m getting a compile error that’s making me pull my hair out. I suspect it’s something simple, but I can’t seem to figure it out.

I have a subclass of [FONT=Courier New]ACharacter called [FONT=Courier New]ABaseNPCCharacter, which has a lot of generic code to determine things like LOS, nearby friend and enemies, etc.

There are two subclasses of ABaseNPCCharacter ([FONT=Courier New]AEnemyCharacter and [FONT=Courier New]AFriendCharacter), but as of right now they are empty subclasses except they add a tag to the Actor’s [FONT=Courier New]Tag array.

All was well until I went to override [FONT=Courier New]PostInitializeComponents() in [FONT=Courier New]ABaseNPCCharacter.

I added this to ABaseNPCCharacter.h:



virtual void PostInitializeComponents() override;

and this to ABaseNPCCharacter.cp:



void ABaseNPCCharacter::PostInitializeComponents()
{
    Super::PostInitializeComponents();
    
    if (WaypointAutoBuildTag != NULL)
    {
        // TODO: Build waypoint array from tag
    }
    
}

Basically, just a stub for future functionality. When I go to compile, I get this result, though;



[11/11] Link UE4Editor-RepublicSniperAI-Mac-DebugGame.dylib
Undefined symbols for architecture x86_64:
  "ABaseNPCCharacter::PostInitializeComponents()", referenced from:
      vtable for AEnemyCharacter in EnemyCharacter.cpp.o
      vtable for AFriendCharacter in FriendCharacter.cpp.o
  "vtable for ABaseNPCCharacter", referenced from:
      ABaseNPCCharacter::ABaseNPCCharacter(FPostConstructInitializeProperties const&) in BaseNPCCharacter.cpp.o
      ABaseNPCCharacter::~ABaseNPCCharacter() in EnemyCharacter.cpp.o
      ABaseNPCCharacter::~ABaseNPCCharacter() in FriendCharacter.cpp.o
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
-------- End Detailed Actions Stats -----------------------------------------------------------
ERROR: UBT ERROR: Failed to produce item: /Users//Dropbox (MartianCraft)/RepublicSniperAI/Binaries/Mac/UE4Editor-RepublicSniperAI-Mac-DebugGame.dylib
Cumulative action seconds (8 processors): 0.00 building projects, 55.85 compiling, 0.00 creating app bundles, 0.00 generating debug info, 0.17 linking, 0.00 other
UBT execution time: 14.11 seconds
Command /Users/Shared/UnrealEngine/4.4/Engine/Build/BatchFiles/Mac/RocketBuild.sh failed with exit code 2

I’ve tried a bunch of permuatations, including also adding overrides to the child classes, but nothing seems to get rid of this message. I’ve very confused, because neither AFriendCharacter or AEnemyCharacter implements a destructor.

Please, if anyone knows what boneheaded thing I’m doing here, I’d love to be pointed in the right direction.

Thanks!

2

The code looks right and I event tried it out (Using VS2013 Update 4).

Unless the problem is else where in the header, perhaps it’s something to do with your compiler setup? http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-April/020637.html

3

Hmm… I’ve tried both GCC and LLVM as my C++ compiler, I’ve tried C++14 and C++11 (both GNU and LLVM’s library) in addition to the compiler default value. I even tried C++98. I’ve also tried every stdlib option I can think of.

My C++ is a little rusty, admittedly, but this is making me feel downright stupid.

4

Well I’m stumped. This perhaps needs someone with a Mac to try out.

I remember when developing iOS apps in C++ the file extension made a huge difference. Perhaps try .cpp But that was making sure Objective-C and C++ play nice. Yup scrapping the bottom of the barrel here…

Other than that… perhaps post your entire header file? But I doubt it’ll help.

I’m guessing it’s an obscure environmental issue.

Hopefully someone working on a Mac can chime in.

Edit: Trust me you’re not stupid.