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Is this a bug or I am doing something wrong?

Dear everyone,

I found this weird bug, and I wanted to check with you if it is really a bug before submitting a ticket.

Steps to reproduce it

I have been using UE4.24.3 and VS2019.

  1. Create a new empty C++ project.
  2. Add in the *PrivateDependencyModuleNames *the following (it is already there, you need to uncomment it):

PrivateDependencyModuleNames.AddRange(new string] { "Slate", "SlateCore" });

  1. Create a new C++ class, e.g. an actor named MyActor.
  2. Create a new function that contains an *FText Property *and it is a UFUNCTION, like the following:

UFUNCTION(BlueprintCallable)
	void MyFunction(FText MyParameter);

  1. The definition in the .cpp can be empty:

void AMyActor::MyFunction(FText MyParameter)
	{
	}

  1. Package or Launch the project on an Android Device.

This is the error that I got (the project is called TestAndroid2):


[2/5] MyActor.cpp [armv7-es2]
LogPlayLevel:     In file included from D:/Unreal Projects/TestingProjects/TestAndroid2/Source/TestAndroid2/MyActor.cpp:4:
LogPlayLevel: Error:     D:/Unreal Projects/TestingProjects/TestAndroid2/Source/TestAndroid2/MyActor.h(13,2):  error: incomplete type 'UTextProperty' named in nested name specifier
LogPlayLevel:             GENERATED_BODY()
LogPlayLevel:             ^~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ObjectMacros.h(593,29):  note: expanded from macro 'GENERATED_BODY'
LogPlayLevel:     #define GENERATED_BODY(...) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_GENERATED_BODY);
LogPlayLevel:                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ObjectMacros.h(588,37):  note: expanded from macro 'BODY_MACRO_COMBINE'
LogPlayLevel:     #define BODY_MACRO_COMBINE(A,B,C,D) BODY_MACRO_COMBINE_INNER(A,B,C,D)
LogPlayLevel:                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ObjectMacros.h(587,43):  note: expanded from macro 'BODY_MACRO_COMBINE_INNER'
LogPlayLevel:     #define BODY_MACRO_COMBINE_INNER(A,B,C,D) A##B##C##D
LogPlayLevel:                                               ^~~~~~~~~~
LogPlayLevel:     note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
LogPlayLevel:     D:/Unreal Projects/TestingProjects/TestAndroid2/Intermediate/Build/Android/UE4/Inc/TestAndroid2\MyActor.generated.h(102,2):  note: expanded from macro 'TestAndroid2_Source_TestAndroid2_MyActor_h_13_GENERATED_BODY'
LogPlayLevel:             TestAndroid2_Source_TestAndroid2_MyActor_h_13_RPC_WRAPPERS_NO_PURE_DECLS \
LogPlayLevel:             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     D:/Unreal Projects/TestingProjects/TestAndroid2/Intermediate/Build/Android/UE4/Inc/TestAndroid2\MyActor.generated.h(33,18):  note: expanded from macro 'TestAndroid2_Source_TestAndroid2_MyActor_h_13_RPC_WRAPPERS_NO_PURE_DECLS'
LogPlayLevel:                     P_GET_PROPERTY(UTextProperty,Z_Param_MyParameter); \
LogPlayLevel:                     ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ScriptMacros.h(44,2):  note: expanded from macro 'P_GET_PROPERTY'
LogPlayLevel:             PropertyType::TCppType ParamName = PropertyType::GetDefaultPropertyValue();                                     \
LogPlayLevel:             ^~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/Core/Public\UObject/UObjectHierarchyFwd.h(33,10):  note: forward declaration of 'UTextProperty'
LogPlayLevel:     class                           UTextProperty;
LogPlayLevel:                                     ^
LogPlayLevel:     In file included from D:/Unreal Projects/TestingProjects/TestAndroid2/Source/TestAndroid2/MyActor.cpp:4:
LogPlayLevel: Error:     D:/Unreal Projects/TestingProjects/TestAndroid2/Source/TestAndroid2/MyActor.h(13,2):  error: incomplete type 'UTextProperty' named in nested name specifier
LogPlayLevel:             GENERATED_BODY()
LogPlayLevel:             ^~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ObjectMacros.h(593,29):  note: expanded from macro 'GENERATED_BODY'
LogPlayLevel:     #define GENERATED_BODY(...) BODY_MACRO_COMBINE(CURRENT_FILE_ID,_,__LINE__,_GENERATED_BODY);
LogPlayLevel:                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ObjectMacros.h(588,37):  note: expanded from macro 'BODY_MACRO_COMBINE'
LogPlayLevel:     #define BODY_MACRO_COMBINE(A,B,C,D) BODY_MACRO_COMBINE_INNER(A,B,C,D)
LogPlayLevel:                                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ObjectMacros.h(587,43):  note: expanded from macro 'BODY_MACRO_COMBINE_INNER'
LogPlayLevel:     #define BODY_MACRO_COMBINE_INNER(A,B,C,D) A##B##C##D
LogPlayLevel:                                               ^~~~~~~~~~
LogPlayLevel:     note: (skipping 1 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
LogPlayLevel:     D:/Unreal Projects/TestingProjects/TestAndroid2/Intermediate/Build/Android/UE4/Inc/TestAndroid2\MyActor.generated.h(102,2):  note: expanded from macro 'TestAndroid2_Source_TestAndroid2_MyActor_h_13_GENERATED_BODY'
LogPlayLevel:             TestAndroid2_Source_TestAndroid2_MyActor_h_13_RPC_WRAPPERS_NO_PURE_DECLS \
LogPlayLevel:             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     D:/Unreal Projects/TestingProjects/TestAndroid2/Intermediate/Build/Android/UE4/Inc/TestAndroid2\MyActor.generated.h(33,18):  note: expanded from macro 'TestAndroid2_Source_TestAndroid2_MyActor_h_13_RPC_WRAPPERS_NO_PURE_DECLS'
LogPlayLevel:                     P_GET_PROPERTY(UTextProperty,Z_Param_MyParameter); \
LogPlayLevel:                     ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/CoreUObject/Public\UObject/ScriptMacros.h(44,37):  note: expanded from macro 'P_GET_PROPERTY'
LogPlayLevel:             PropertyType::TCppType ParamName = PropertyType::GetDefaultPropertyValue();                                     \
LogPlayLevel:                                                ^~~~~~~~~~~~~~
LogPlayLevel:     C:/Program Files/Epic Games/UE_4.24/Engine/Source/Runtime/Core/Public\UObject/UObjectHierarchyFwd.h(33,10):  note: forward declaration of 'UTextProperty'
LogPlayLevel:     class                           UTextProperty;
LogPlayLevel:                                     ^
LogPlayLevel:     2 errors generated.
LogPlayLevel:     [3/5] MyActor.gen.cpp [armv7-es2]
LogPlayLevel: Took 9.7787936s to run UnrealBuildTool.exe, ExitCode=5

Workaround
However, I have found a way to make it compile and work, but I feel it is more a workaround, rather than the proper way to go.
If you include at the beginning of your MyActor.h the following include:


#include "UObject/TextProperty.h"

Then, everything compiles without any problems.

Of course, if you remove the *PrivateDependency *to *Slate *and SlateCore, everything compiles.

Is this a bug?
Can someone try if this produces a compiling error? Is there a way to proceed, or is it a bug and should I submit a ticket?

I found that this is not an isolate case. In fact, it happens also in other two cases:

UWorld
if I try to use a UWorld*, so calling this in the code, any function:


GetWorld()->GetGameInstance();

AND I have this in the build file:


PrivateDependencyModuleNames.AddRange(new string] { "Slate", "SlateCore" });

Then compiling for Android results in this error:


error: member access into incomplete type 'UWorld'

unless I either drop the dependency to *Slate *and SlateCore or I use


#include "Engine/World.h"

FTimerManager
Similar if I use the FTimerManager, like adding this in any code:
GetWorld()->GetTimerManager();

AND I have this in the build file:


PrivateDependencyModuleNames.AddRange(new string] { "Slate", "SlateCore" });

Then compiling for Android results in this error:


error: member access into incomplete type 'FTimerManager'

unless I either drop the dependency to *Slate *and SlateCore or I use


#include "TimerManager.h"

Is this a bug?

The fact that this error appears only when there is the dependency to *Slate *and *SlateCore *makes me believe that it is, so unless some of you have some explanation, I will submit a report ticket as a bug. Thankfully for the meantime I have a workaround (using the Include files).