Question

我正在关注this tutorial，我完全复制并粘贴了Countdown.h和Countdown.cpp的内容。

Visual Studio Code（我在Mac上）提供以下提示

#include errors detected. Please update your includePath. IntelliSense features for this translation unit (/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.h) will be provided by the Tag Parser.
cannot open source file "new" (dependency of "GameFramework/Actor.h")

在这一行

#include "GameFramework/Actor.h"

虽然我从UE获得的编译错误如下

Running Mono...

Setting up Mono
~/Documents/UE_4.18/Engine ~/Documents/UE_4.18/Engine/Binaries/Mac
Compiling game modules for hot reload
Parsing headers for HowTo_VTEEditor
  Running UnrealHeaderTool "/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/HowTo_VTE.uproject" "/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/HowTo_VTEEditor/Development/HowTo_VTEEditor.uhtmanifest" -LogCmds="loginit warning, logexit warning, logdatabase error" -Unattended -WarningsAsErrors -installed
Reflection code generated for HowTo_VTEEditor in 10,277899 seconds
Performing 3 actions (5 in parallel)
[2/3] Compile Countdown.cpp
[1/3] Compile Countdown.gen.cpp
In file included from /Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/UE4Editor/Inc/HowTo_VTE/Countdown.gen.cpp:8:
../../../Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.h:29:5: error: unknown type name 'UTextRenderComponent'
    UTextRenderComponent* CountdownText;
    ^
../../../Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.h:12:5: error: cannot initialize return object of type 'UObject *' with an rvalue of type 'ACountdown *'
    GENERATED_BODY()
    ^~~~~~~~~~~~~~~~
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:585:29: note: expanded from macro 'GENERATED_BODY'
#define GENERATED_BODY(...) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_GENERATED_BODY);
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:580:37: note: expanded from macro 'BODY_MACRO_COMBINE'
#define BODY_MACRO_COMBINE(A,B,C,D) BODY_MACRO_COMBINE_INNER(A,B,C,D)
                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:579:43: note: expanded from macro 'BODY_MACRO_COMBINE_INNER'
#define BODY_MACRO_COMBINE_INNER(A,B,C,D) A##B##C##D
                                          ^~~~~~~~~~
note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
../../../Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/UE4Editor/Inc/HowTo_VTE/Countdown.generated.h:81:2: note: expanded from macro 'HowTo_VTE_Source_HowTo_VTE_Countdown_h_12_GENERATED_BODY'
        HowTo_VTE_Source_HowTo_VTE_Countdown_h_12_ENHANCED_CONSTRUCTORS \
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/UE4Editor/Inc/HowTo_VTE/Countdown.generated.h:57:54: note: expanded from macro 'HowTo_VTE_Source_HowTo_VTE_Countdown_h_12_ENHANCED_CONSTRUCTORS'
        DECLARE_VTABLE_PTR_HELPER_CTOR(NO_API, ACountdown); \
                                                            ^
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:1387:11: note: expanded from macro '\
DEFINE_VTABLE_PTR_HELPER_CTOR_CALLER'
                        return new (EC_InternalUseOnlyConstructor, (UObject*)GetTransientPackage(), NAME_None, RF_NeedLoad | RF_ClassDefaultObject | RF_TagGarbageTemp) TClass(Helper); \
                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:1:
../../../Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.h:29:5: error: unknown type name 'UTextRenderComponent'
    UTextRenderComponent* CountdownText;
    ^
../../../Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.h:12:5: error: cannot initialize return object of type 'UObject *' with an rvalue of type 'ACountdown *'
    GENERATED_BODY()
    ^~~~~~~~~~~~~~~~
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:585:29: note: expanded from macro 'GENERATED_BODY'
#define GENERATED_BODY(...) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_GENERATED_BODY);
                            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:580:37: note: expanded from macro 'BODY_MACRO_COMBINE'
#define BODY_MACRO_COMBINE(A,B,C,D) BODY_MACRO_COMBINE_INNER(A,B,C,D)
                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:579:43: note: expanded from macro 'BODY_MACRO_COMBINE_INNER'
#define BODY_MACRO_COMBINE_INNER(A,B,C,D) A##B##C##D
                                          ^~~~~~~~~~
note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
../../../Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/UE4Editor/Inc/HowTo_VTE/Countdown.generated.h:81:2: note: expanded from macro 'HowTo_VTE_Source_HowTo_VTE_Countdown_h_12_GENERATED_BODY'
        HowTo_VTE_Source_HowTo_VTE_Countdown_h_12_ENHANCED_CONSTRUCTORS \
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../../Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/UE4Editor/Inc/HowTo_VTE/Countdown.generated.h:57:54: note: expanded from macro 'HowTo_VTE_Source_HowTo_VTE_Countdown_h_12_ENHANCED_CONSTRUCTORS'
        DECLARE_VTABLE_PTR_HELPER_CTOR(NO_API, ACountdown); \
                                                            ^
Runtime/CoreUObject/Public/UObject/ObjectMacros.h:1387:11: note: expanded from macro '\
DEFINE_VTABLE_PTR_HELPER_CTOR_CALLER'
                        return new (EC_InternalUseOnlyConstructor, (UObject*)GetTransientPackage(), NAME_None, RF_NeedLoad | RF_ClassDefaultObject | RF_TagGarbageTemp) TClass(Helper); \
                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:11:44: error: use of undeclared identifier 'UTextRenderComponent'
    CountdownText = CreateDefaultSubobject<UTextRenderComponent>(TEXT("CountdownNumber"));
                                           ^
/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:12:43: error: use of undeclared identifier 'EHTA_Center'; did you mean 'kTXNCenter'?
    CountdownText->SetHorizontalAlignment(EHTA_Center);
                                          ^~~~~~~~~~~
                                          kTXNCenter
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk/System/Library/Frameworks/Carbon.framework/Frameworks/HIToolbox.framework/Headers/MacTextEditor.h:793:3: note: 'kTXNCenter' declared here
  kTXNCenter                    = 4,
  ^
/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:22:12: error: cannot initialize object parameter of type 'AActor' with an expression of type 'ACountdown'
    Super::BeginPlay();
           ^~~~~~~~~
/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:25:5: error: cannot initialize object parameter of type 'const AActor' with an expression of type 'ACountdown'
    GetWorldTimerManager().SetTimer(CountdownTimerHandle, this, &ACountdown::AdvanceTimer, 1.0f, true);
    ^~~~~~~~~~~~~~~~~~~~
/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:31:12: error: no matching member function for call to 'Tick'
    Super::Tick( DeltaTime );
    ~~~~~~~^~~~
Runtime/Engine/Classes/GameFramework/Actor.h:2077:15: note: candidate function not viable: no known conversion from 'ACountdown' to 'AActor' for object argument
        virtual void Tick( float DeltaSeconds );
                     ^
Runtime/Engine/Classes/GameFramework/Actor.h:2432:15: note: candidate function not viable: requires 2 arguments, but 1 was provided
        virtual void Tick( float DeltaTime, enum ELevelTick TickType ) final
                     ^
/Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.cpp:47:9: error: cannot initialize object parameter of type 'const AActor' with an expression of type 'ACountdown'
        GetWorldTimerManager().ClearTimer(CountdownTimerHandle);
        ^~~~~~~~~~~~~~~~~~~~
2 errors generated.
8 errors generated.
ERROR: UBT ERROR: Failed to produce item: /Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Binaries/Mac/UE4Editor-HowTo_VTE-6063.dylib
Total build time: 28,61 seconds (Local executor: 0,00 seconds)

就好像两个错误是相关的，但我没有得到可能出错的错误。我注意到我的项目位于/Documents/Unreal Projects/HowTo_VTE/Source/HowToVTE/Countdown.cpp 虚幻的东西在Documents/UE_4.18/Engine/... 这可能是找不到包含物的罪魁祸首吗？

编辑：我尝试使用带有Actor.h的绝对路径的include但是我得到了相同的编译错误

Answer 1

我在Unreal的Answerhub上发布了同样的问题，一位善良的用户能够提供解决方案。

你可以看到它here

简而言之：将#include "Runtime/Engine/Classes/Components/TextRenderComponent.h"添加到Countdown.h中的包含中（当然，将自动生成的包含保留为最后一个）

Answer 2

以下是如何理解此错误告诉您的内容：

[1/3] Compile Countdown.gen.cpp
In file included from /Users/massimobortolamei/Documents/Unreal Projects/HowTo_VTE/Intermediate/Build/Mac/UE4Editor/Inc/HowTo_VTE/Countdown.gen.cpp:8:
../../../Unreal Projects/HowTo_VTE/Source/HowTo_VTE/Countdown.h:29:5: error: unknown type name 'UTextRenderComponent'
    UTextRenderComponent* CountdownText;
    ^

您的编译器告诉您它不知道UTextRenderComponent是什么，因为尚未包含定义它的文件。这就是添加include（#include "Runtime/Engine/Classes/Components/TextRenderComponent.h"）的原因。但是，在现有标题中包含其他标题通常不是一个好主意，因为这会使您在大型项目上的编译时间膨胀（Here's这是对其原因的一个合理解释。）

更好的做法是在标头中转发声明UTextRenderComponent，然后在.cpp文件中包含TextRenderComponent标头。（Some info关于前向声明）Unreal的构建工具使用class关键字提供了一种方便的方法。

声明你的成员变量：

class UTextRenderComponent* CountdownText;

然后在.cpp文件中包含必需的标头。您在此实例中所做的是告诉您的编译器UTextRenderComponent是一个类，并且您承诺稍后提供该定义。你的编译器在解析Countdown.h时不需要知道它是什么定义因为你只是包含一个指向类的指针，所以它不需要知道它的大小或其他任何东西 - 只是它是一个在其他地方定义了类。

所以，是的，您在上面找到的解决方案可行，但不如在标题中向前声明您的类，然后在您的实现中包含其他标题。

虚幻：“未知类型名称UTextRenderComponent”编译错误，同时遵循教程

2 个答案: