Unresolved external symbol: inheriting from URadialForceComponent

Development Programming & Scripting
1

This question was already posted at the forums but I’m hoping to find answers here since this looks like an engine problem.

After inheriting from URadialForceComponent and trying to compile, I ended up with several unresolved external symbol errors.

[.h]

#pragma once

#include "PhysicsEngine/RadialForceComponent.h"
#include "SF_RadialForceComponent.generated.h"

/**
 * 
 */
UCLASS()
class SHOOTERGAME_API USF_RadialForceComponent : public URadialForceComponent
{
	GENERATED_BODY()

	
};

[.cpp]

#include "ShooterGame.h"
#include "SF_RadialForceComponent.h"

Compiling this gives me a set of errors:

1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::FireImpulse(void)" (?FireImpulse@URadialForceComponent@@UEAAXXZ)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::FireImpulse(void)" (?FireImpulse@URadialForceComponent@@UEAAXXZ)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::FireImpulse(void)" (?FireImpulse@URadialForceComponent@@UEAAXXZ)
1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::AddObjectTypeToAffect(class TEnumAsByte<enum EObjectTypeQuery>)" (?AddObjectTypeToAffect@URadialForceComponent@@UEAAXV?$TEnumAsByte@W4EObjectTypeQuery@@@@@Z)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::AddObjectTypeToAffect(class TEnumAsByte<enum EObjectTypeQuery>)" (?AddObjectTypeToAffect@URadialForceComponent@@UEAAXV?$TEnumAsByte@W4EObjectTypeQuery@@@@@Z)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::AddObjectTypeToAffect(class TEnumAsByte<enum EObjectTypeQuery>)" (?AddObjectTypeToAffect@URadialForceComponent@@UEAAXV?$TEnumAsByte@W4EObjectTypeQuery@@@@@Z)
1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::RemoveObjectTypeToAffect(class TEnumAsByte<enum EObjectTypeQuery>)" (?RemoveObjectTypeToAffect@URadialForceComponent@@UEAAXV?$TEnumAsByte@W4EObjectTypeQuery@@@@@Z)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::RemoveObjectTypeToAffect(class TEnumAsByte<enum EObjectTypeQuery>)" (?RemoveObjectTypeToAffect@URadialForceComponent@@UEAAXV?$TEnumAsByte@W4EObjectTypeQuery@@@@@Z)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl URadialForceComponent::RemoveObjectTypeToAffect(class TEnumAsByte<enum EObjectTypeQuery>)" (?RemoveObjectTypeToAffect@URadialForceComponent@@UEAAXV?$TEnumAsByte@W4EObjectTypeQuery@@@@@Z)
1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::TickComponent(float,enum ELevelTick,struct FActorComponentTickFunction *)" (?TickComponent@URadialForceComponent@@MEAAXMW4ELevelTick@@PEAUFActorComponentTickFunction@@@Z)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::TickComponent(float,enum ELevelTick,struct FActorComponentTickFunction *)" (?TickComponent@URadialForceComponent@@MEAAXMW4ELevelTick@@PEAUFActorComponentTickFunction@@@Z)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::TickComponent(float,enum ELevelTick,struct FActorComponentTickFunction *)" (?TickComponent@URadialForceComponent@@MEAAXMW4ELevelTick@@PEAUFActorComponentTickFunction@@@Z)
1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::BeginPlay(void)" (?BeginPlay@URadialForceComponent@@MEAAXXZ)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::BeginPlay(void)" (?BeginPlay@URadialForceComponent@@MEAAXXZ)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::BeginPlay(void)" (?BeginPlay@URadialForceComponent@@MEAAXXZ)
1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::PostLoad(void)" (?PostLoad@URadialForceComponent@@MEAAXXZ)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::PostLoad(void)" (?PostLoad@URadialForceComponent@@MEAAXXZ)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::PostLoad(void)" (?PostLoad@URadialForceComponent@@MEAAXXZ)
1>Module.ShooterGame.1_of_3.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::PostEditChangeProperty(struct FPropertyChangedEvent &)" (?PostEditChangeProperty@URadialForceComponent@@MEAAXAEAUFPropertyChangedEvent@@@Z)
1>ShooterGame.generated.1.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::PostEditChangeProperty(struct FPropertyChangedEvent &)" (?PostEditChangeProperty@URadialForceComponent@@MEAAXAEAUFPropertyChangedEvent@@@Z)
1>ShooterGame.generated.2.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl URadialForceComponent::PostEditChangeProperty(struct FPropertyChangedEvent &)" (?PostEditChangeProperty@URadialForceComponent@@MEAAXAEAUFPropertyChangedEvent@@@Z)

I’m using UE4 version 4.15.

After doing some research, I found a 2 year-old Answerhub thread with exactly the same error, but with no clear solutions.

Any thoughts? Thanks.

2

Hi ,

The reason that you are getting these errors is because URadialForceComponent is missing ENGINE_API in its declaration. Simply add that tag and remove the MinimalAPI meta data tag to get it to compile successfully.

EDIT: I created a PR that addresses this issue #3346.

Cheers,

3

Thanks.

Strangely, it did not compiled succesfully, giving me these errors:

1>D:\Epic Games\UE_4.15\Engine\Source\Runtime\Engine\Classes\PhysicsEngine/RadialForceComponent.h(18): error C2487: 'GetPrivateStaticClass': member of dll interface class may not be declared with dll interface
1>D:\Epic Games\UE_4.15\Engine\Source\Runtime\Engine\Classes\PhysicsEngine/RadialForceComponent.h(18): error C2487: 'URadialForceComponent::{ctor}': member of dll interface class may not be declared with dll interface

Did you manage to compile it?

4

I did a full recompile on the engine, and it completed without issues :S .

5

Created a clean project to test this.

At first I compiled the whole solution, and it was sucessfull:

========== Rebuild All: 2 succeeded, 0 failed, 0 skipped ==========

Then, I did the changings at RadialForceComponent.h as suggested, and after compilling it gave me this:

2>D:\Epic Games\UE_4.15\Engine\Source\Runtime\Engine\Classes\PhysicsEngine/RadialForceComponent.h(18): error C2487: 'GetPrivateStaticClass': member of dll interface class may not be declared with dll interface
2>D:\Epic Games\UE_4.15\Engine\Source\Runtime\Engine\Classes\PhysicsEngine/RadialForceComponent.h(18): error C2487: 'URadialForceComponent::{ctor}': member of dll interface class may not be declared with dll interface
2>ERROR : UBT error : Failed to produce item: D:\UnrealEngineProjects\RadCompBlank\Binaries\Win64\UE4Editor-RadCompBlank.dll
2>  Total build time: 71,15 seconds (Local executor: 0,00 seconds)
2>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Microsoft.MakeFile.Targets(46,5): error MSB3073: The command ""D:\Epic Games\UE_4.15\Engine\Build\BatchFiles\Rebuild.bat" RadCompBlankEditor Win64 Development "D:\UnrealEngineProjects\RadCompBlank\RadCompBlank.uproject" -waitmutex" exited with code -1.
========== Rebuild All: 1 succeeded, 1 failed, 0 skipped ==========

How did you manage to make this work? :o