Compile errors with generated.h

Development Platform & Builds
, , , , ,
1

I’m getting the compile error:

Expected an include at the top of the header: ‘include “MessageHandling.generated.h”’

in my header file “MessageHandling.h”. The error seems to be caused by a macro in the file which includes the UCLASS macro:

#define DECLARE_MSG_TYPE_AND_DATA(messageName, messageDataClass) \
	UCLASS() \
	class messageName : public UObject, public messageDataClass { \
		GENERATED_BODY() \
		public: \
			template<typename... Arguments> \
			messageName(Arguments&&... args) : messageDataClass(std::forward<Arguments>(args)...)			{ } \
	};

If I include MessageHandling.generated.h at the top of the file I instead get the error:

Cannot open include file: ‘MessageHandling.generated.h’: No such file or directory
So I’m not sure how to make the system happy. If I remove the UCLASS macro from this macro then the error goes away, but we need it, so, yeah… The generated.h files have been a constant source of headache for our project, so perhaps someone can direct me to some documentation about how the system works so we can finally get some work done.

2

How do you add code to your project? The .generated.h files are, like their name implies, automatically generated when you add a class to your project. Maybe you are adding the class without using the “Add Code to Project” in the editor?

3

This macro won’t work because UHT cannot expand it. The same with conditional compilation (#if, #else, …). You have to define each class header by hand instead of doing it with handy macro.

4

I was afraid of that. I already ran into the issues with #if/#else, and had a feeling it was related. It’s a bummer to see the limitations imposed by their use of an independent header/reflection tool. It’s been a constant pain for us with its restrictions on how we structure our code.

5

If you regenerate your solution, it will create the .generated.h files.

See this answer for more info on generated files.

This answer describes how to force regeneration.