Circular dependency detected for filename

Development Programming & Scripting C++
1

What is a ‘circular dependency’?

1>------ Rebuild All started: Project: DistantHome, Configuration: DebugGame_Editor x64 ------
1> Cleaning DistantHomeEditor Binaries…
1> Compiling game modules for hot reload
1> Compiling game modules for hot reload
1> Parsing headers for DistantHomeEditor
1>LogCompile : error : Circular dependency detected for filename D:\Library Storage\Documents\Unreal Projects\DistantHome\Source\DistantHome\Public\Game\DHGameInfo.h!
1> Reflection code generated for DistantHomeEditor
1> Performing 14 actions (2 in parallel)
1> [2/14] Resource ModuleVersionResource.rc.inl
1> PCH.DistantHome.h.cpp
1> [3/14] Resource PCLaunch.rc
1>d:\library storage\documents\unreal projects\distanthome\source\distanthome\Public/Game/DHGameInfo.h(43): error C3431: ‘EItemType’ : an unscoped enumeration cannot be redeclared as a scoped enumeration
1> -------- End Detailed Actions Stats -----------------------------------------------------------
1>ERROR : UBT error : Failed to produce item: D:\Library Storage\Documents\Unreal Projects\DistantHome\Binaries\Win64\UE4Editor-DistantHome-894-Win64-DebugGame.dll
1> Total build time: 61.86 seconds
1>C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.MakeFile.Targets(43,5): error MSB3075: The command ““C:\Program Files\Epic Games\4.8\Engine\Build\BatchFiles\Rebuild.bat” DistantHomeEditor Win64 DebugGame “D:\Library Storage\Documents\Unreal Projects\DistantHome\DistantHome.uproject” -rocket” exited with code 5. Please verify that you have sufficient rights to run this command.
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========


// Copyright 2015 Dirt Productions. All rights reserved.

#pragma once

#include "GameFramework/Info.h"
#include "Public/Item/Weapon/DHWeapon.h"
#include "DHGameInfo.generated.h"

/**
 * Class used to store game's enumerations, structures, and basically anything else that applies to the entire game.
 */
UCLASS()
class DISTANTHOME_API ADHGameInfo : public AInfo
{
	GENERATED_BODY()

};

// Type of match
UENUM(BlueprintType)
enum class EGameType : uint8
{
	SingleplayerNormal UMETA(DisplayName = "Campaign"),
	SingleplayerCustom UMETA(DisplayName = "AI Match"),
	MultiplayerNormal UMETA(DisplayName = "Multiplayer"),
	MultiplayerRanked UMETA(DisplayName = "Ranked Match")
};

// Available weapon slots
UENUM(BlueprintType)
enum class EWeaponSlot : uint8
{
	NoWeapon UMETA(DisplayName = "No Weapon"),
	PrimaryWeapon UMETA(DisplayName = "Primary Weapon"),
	SecondaryWeapon UMETA(DisplayName = "Secondary Weapon"),
	MeleeWeapon UMETA(DisplayName = "Melee Weapon"),
	SpecialWeapon UMETA(DisplayName = "Ability")
};

// Type of game item
UENUM(BlueprintType)
enum class EItemType : uint8
{
	Weapon UMETA(DisplayName = "Weapon"),
	SpecialWeapon UMETA(DisplayName = "Ability")
};

/**
 * Player faction data
 * 'SpectatorTeam' is to clear confusion between spectators on a separate team and temporary spectators on either ARC or BAT after they die.
 * 'NoFaction' is only used for teamless game modes.
 */
UENUM(BlueprintType)
enum class EPlayerFaction : uint8
{
	NoFaction UMETA(DisplayName = "No Faction"),
	SpectatorTeam UMETA(DisplayName = "Spectators"),
	ARC UMETA(DisplayName = "A.R.C."),
	BAT UMETA(DisplayName = "B.A.T.")
};

// Burst fire information
USTRUCT()
struct FWeaponBurstData
{
	GENERATED_USTRUCT_BODY();

	UPROPERTY()
		uint16 ShotsPerBurst;

	UPROPERTY()
		uint16 ShotsFired;

	UPROPERTY()
		float DelayPerShot;

	FWeaponBurstData()
	{
		ShotsPerBurst = 3;
		ShotsFired = 0;
		DelayPerShot = 0.09f;
	}

	bool IsValid()
	{
		if (ShotsPerBurst >= ShotsFired) return true;
		else return false;
	}
};

// Per-weapon ammo data
USTRUCT()
struct FWeaponAmmoData
{
	GENERATED_USTRUCT_BODY();

	UPROPERTY()
		uint16 MaxLoadedAmmo;

	UPROPERTY()
		uint16 MaxCarryAmmo;

	UPROPERTY()
		uint16 LoadedAmmo;

	UPROPERTY()
		uint16 CarryAmmo;

	FWeaponAmmoData()
	{
		MaxLoadedAmmo = 30;
		MaxCarryAmmo = 210;
		LoadedAmmo = 30;
		CarryAmmo = 150;
	}

	bool IsValid()
	{
		if (LoadedAmmo <= MaxLoadedAmmo && CarryAmmo <= MaxCarryAmmo) return true;
		else return false;
	}
};

// Per-special weapon data
USTRUCT()
struct FSpecialWeaponAmmoData
{
	GENERATED_USTRUCT_BODY();

	UPROPERTY()
		float RechargeTime;

	UPROPERTY()
		float UseTime;

	UPROPERTY()
		uint16 MaxLoadedAmmo;

	UPROPERTY()
		uint16 LoadedAmmo;

	FSpecialWeaponAmmoData()
	{
		RechargeTime = 30.0f;
		UseTime = 1.0f;
		MaxLoadedAmmo = 4;
		LoadedAmmo = 4;
	}

	bool IsValid()
	{
		if (LoadedAmmo <= MaxLoadedAmmo) return true;
		else return false;
	}
};

// Per-player ammo data
USTRUCT()
struct FPlayerAmmoData
{
	GENERATED_USTRUCT_BODY();

	UPROPERTY()
	struct FWeaponAmmoData PrimaryAmmo;

	UPROPERTY()
	struct FWeaponBurstData PrimaryBurst;

	UPROPERTY()
	struct FWeaponAmmoData SecondaryAmmo;

	UPROPERTY()
	struct FWeaponBurstData SecondaryBurst;

	UPROPERTY()
	struct FSpecialWeaponAmmoData SpecialAmmo;

	FPlayerAmmoData()
	{
		struct FWeaponAmmoData DefaultAmmo;
		DefaultAmmo.MaxLoadedAmmo = 30;
		DefaultAmmo.MaxCarryAmmo = 210;
		DefaultAmmo.LoadedAmmo = 30;
		DefaultAmmo.CarryAmmo = 150;

		struct FWeaponBurstData DefaultBurst;
		DefaultBurst.ShotsPerBurst = 3;
		DefaultBurst.ShotsFired = 0;
		DefaultBurst.DelayPerShot = 0.09f;

		struct FSpecialWeaponAmmoData DefaultSpecial;
		DefaultSpecial.LoadedAmmo = 4;
		DefaultSpecial.MaxLoadedAmmo = 4;
		DefaultSpecial.RechargeTime = 30.0f;
		DefaultSpecial.UseTime = 1.0f;

		PrimaryAmmo, SecondaryAmmo = DefaultAmmo;
		PrimaryBurst, SecondaryBurst = DefaultBurst;
		SpecialAmmo = DefaultSpecial;
	}

	EWeaponSlot GetBestWeapon()
	{
		if (PrimaryAmmo.IsValid()) return EWeaponSlot::PrimaryWeapon;
		else if (SecondaryAmmo.IsValid()) return EWeaponSlot::SecondaryWeapon;
		else return EWeaponSlot::MeleeWeapon;
	}

	bool IsValid(bool bCheckSpecialWeapon)
	{
		if (PrimaryAmmo.IsValid() && SecondaryAmmo.IsValid())
		{
			if (bCheckSpecialWeapon)
			{
				if (SpecialAmmo.IsValid()) return true;
				else return false;
			}
			else return true;
		}
		else return false;
	}
};

// Weapon information
USTRUCT()
struct FWeaponInfo
{
	GENERATED_USTRUCT_BODY();

	UPROPERTY()
		FName WeaponDisplayName;

	UPROPERTY()
		FString WeaponID;

	UPROPERTY()
		bool bIsCapableOfFullyAutomatic;

	UPROPERTY()
		EWeaponSlot IntendedSlot;

	UPROPERTY()
		struct FWeaponAmmoData DefaultAmmoData;

	FWeaponInfo()
	{
		WeaponDisplayName = "My Weapon";
		WeaponID = "AssaultRifle_01";
		bIsCapableOfFullyAutomatic = true;
		IntendedSlot = EWeaponSlot::PrimaryWeapon;

		struct FWeaponAmmoData DefaultAmmo;
		DefaultAmmo.MaxLoadedAmmo = 30;
		DefaultAmmo.MaxCarryAmmo = 210;
		DefaultAmmo.LoadedAmmo = 30;
		DefaultAmmo.CarryAmmo = 150;

		DefaultAmmoData = DefaultAmmo;
	}
};

// Special weapon information
USTRUCT()
struct FSpecialWeaponInfo
{
	GENERATED_USTRUCT_BODY();

	UPROPERTY()
		FString WeaponDisplayName;

	UPROPERTY()
		FString WeaponID;

	UPROPERTY()
	struct FSpecialWeaponAmmoData DefaultAmmoData;

	FSpecialWeaponInfo()
	{
		WeaponDisplayName = "My Special Weapon";
		WeaponID = "Special_01";

		struct FSpecialWeaponAmmoData DefaultAmmo;
		DefaultAmmo.LoadedAmmo = 5;
		DefaultAmmo.MaxLoadedAmmo = 5;
		DefaultAmmo.RechargeTime = 30.0f;
		DefaultAmmo.UseTime = 1.0f;

		DefaultAmmoData = DefaultAmmo;
	}
};

// Weapon inventory
USTRUCT()
struct FWeaponInventory
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY()
		ADHWeapon* PrimaryWeapon;

	UPROPERTY()
		ADHWeapon* SecondaryWeapon;

	UPROPERTY()
		ADHWeapon* MeleeWeapon;

	UPROPERTY()
		ADHWeapon* SpecialWeapon;

	FWeaponInventory()
	{
	}
};

// Player hitpoints
USTRUCT()
struct FPlayerHitPoints
{
	GENERATED_USTRUCT_BODY()

	UPROPERTY()
		float MaxHitPoints;

	UPROPERTY()
		float CurrentHitPoints;

	FPlayerHitPoints()
	{
		MaxHitPoints, CurrentHitPoints = 100.0f;
	}

	bool IsAlive()
	{
		if (CurrentHitPoints <= MaxHitPoints && CurrentHitPoints > 0.0f) return true;
		else return false;
	}
};
2

Does DHWeapon include DHGameInfo.h?

3

Circular Dependency basically means that two Header files are trying to include each other, and therefore the compiler can’t work out which one to compile first.

It’s a bit of a pain to resolve since it means reworking your #includes slightly, but Forward Declarations can help with this a lot (but only work if you’re not calling functions on or accessing the declared class).

Here’s an example from my own code. AGESGame_DefaultGameMode needs to declare variables of type ‘AGESGame_State’, ‘AGESGame_Satellite’ and ‘AGESGame_Debris’. However - those classes already have the gamemode header in their own include files. In order to avoid a cirular dependency, I have to do this:



// Copyright(C) Stormtide 2015

#pragma once

#include "GameFramework/GameMode.h"
#include "GESGame_DefaultGameMode.generated.h"

// Forward Declarations
class AGESGame_State;
class AGESGame_Satellite;
class AGESGame_Debris;

UCLASS()
class GESGAME_API AGESGame_DefaultGameMode : public AGameMode
{
	GENERATED_BODY()

public:

	AGESGame_Satellite* GetFirstInactiveSatellite();
	AGESGame_Debris* GetFirstInactiveDebris();
}

I can then declare variables of those types in the Gamemode, but I can’t access or call functions on them. All it does is essentially tell the compiler that ‘at some point, these classes will exist’. - But the compiler doesn’t necessarily know what they are. Hope that explains it!

5 Likes
4 

// Copyright 2015 Dirt Productions. All rights reserved.

#pragma once

#include "Public/Item/DHItem.h"
#include "DistantHome.h"
#include "DHWeapon.generated.h"

/**
 * Weapon subclass
 */
UCLASS()
class DISTANTHOME_API ADHWeapon : public ADHItem
{
	GENERATED_BODY()
	
	////////////////////** VARIABLES **////////////////////
public:
	EItemType ItemType;
    
	////////////////////** FUNCTIONS **////////////////////
public:
	// Sets default values for this weapon's properties
	ADHWeapon();
};

This is the code for DHWeapon
What should i forward declare in order for this to work?

I tried declaring enum class EItemType in DHGameInfo, but didn’t work
And I need DHWeapon.h to be included in DHGameInfo because of FWeaponInventory

5

Whenever I hit a point where I need circular dependencies, I make a public base class for the main one, leave the important members in it then include it in both headers that was trying to include each other; then everything works as if it was circular header inclusion and compiles just fine.