Hi again!
I've encountered a weird problem when calling virtual functions on Android (ARM version). It seems like I'm getting a crash whenever I call a inherited function, whether or not it is overwritten by a derived class. For example if I have these two classes:

class Base
{
public:
    virtual void printA()
    {
        LOGI("Base: PrintA called");
    }
    
    virtual void printB()
    {
        LOGI("Base: PrintB called");
    }
};

class Derived : public Base
{
public:
    void printA()
    {
        LOGI("Derived: PrintA called");
    }
};

And I register printA and printB at some point using the following:

scriptEngine->RegisterGlobalFunction("void printA()", asMETHOD(Base, printA), asCALL_THISCALL_ASGLOBAL, derivedObj);
scriptEngine->RegisterGlobalFunction("void printB()", asMETHOD(Base, printB), asCALL_THISCALL_ASGLOBAL, derivedObj);

If I now call either printA or printB in AngleScript, my Android application will crash.

Now, as a disclaimer, I might have messed up my configuration at some point, however I don't know how to track down the problem if it in fact is a configuration problem. I've made sure __GNUC__ and ANDROID is defined. I figure it might have something with the VIRTUAL_BASE_OFFSET macro, but, then again, my lack of the technical know-how makes it difficult for me to track the exact problem down.

Has anyone else got something like this to work?

As a side note; I have managed to register and call simple global functions and different value type objects (strings and math objects), so the problem seems to be quite specific. Also, I cannot explain this, but in my main application, I'm actually able to call some function which are registered in this way (but mostly not), but I'm not able to find any obvious pattern among them

Anyways, looking forward to some feedback!

Okay, so I changed my register calls to the following:

scriptEngine->RegisterGlobalFunction("void printA()", asMETHOD(Derived, printA), asCALL_THISCALL_ASGLOBAL, derivedObj);
scriptEngine->RegisterGlobalFunction("void printB()", asMETHOD(Derived, printB), asCALL_THISCALL_ASGLOBAL, derivedObj);

However, I still get the crash.

Also, on windows, registering my functions using a pointer to the Base class method, and the base class object, actually works just fine. When I call the script functions in AngelScript on windows the Derived's implementation is called, if any. The reason I want to do it this way is because my main application acts like a framework, or a AS wrapper, where platform-specific functionality is implemented thought abstract classes (well, kinda-abstract classes). Is it just coincidental that it works for my windows build, maybe?

I wish I could provide some debug information, but retrieving debug info from Android seems near impossible . Especially since the crash resides in a Android library (libc.so).

Anyways, thanks for responding!

As far as my investigation goes, it appears it only happens to functions which are registered using asCALL_THISCALL_ASGLOBAL. I tested asCALL_THISCALL with a simple reference type class, and it worked just fine. I even tested what would happen if I registered a global property of type Derived, then called a virtual function of Base registered with asCALL_THISCALL, and it still worked. So the issue seems to be specifically regarding asCALL_THISCALL_ASGLOBAL, when calling a method at an object which inherits another (EDIT: also tested now; the derived object doesn't even have to implement any virtual function for it to crash). Here is an updated and corrected sample which will produce the crash:

class Base
{
public:
	virtual void printA()
	{
		LOGI("Base: PrintA called");
	}
	
	virtual void printB()
	{
		LOGI("Base: PrintB called");
	}
};

class Derived : public Base
{
public:
	void printA()
	{
		LOGI("Derived: PrintA called");
	}
};

// ... registering part
Derived *derived = new Derived();
Base *base = static_cast<Base*>(derived);
scriptEngine->RegisterGlobalFunction("void printA()", asMETHOD(Base, printA), asCALL_THISCALL_ASGLOBAL, base);
scriptEngine->RegisterGlobalFunction("void printB()", asMETHOD(Base, printB), asCALL_THISCALL_ASGLOBAL, base);

Both printA and printB will crash.
Thanks again for your help!

Oh sorry, Fixed it, I didn't have this in my original code though. (the wrath of the copy-paste ...)

Hah, nice . Tested the revision, and it worked in the emulator!

Thanks for your help Andreas!