Internal compiler error: C0000005 @ 54D79AFE C++ Builder 10.1 Berlin Update 2

Question

A package using multiple inheritance causes an Access Violation in C++Builder 10.1 Berlin Update 2 using the CLANG based 32-bit and 64-bit compilers.

As soon as the class with multiple inheritance has implementation code, CLANG causes an ICE.

Here is a simple code that will trigger the problem:

// vcl
#include <System.Classes.hpp>

class TClass1
{
public:
    virtual __fastcall ~TClass1() = 0;
};

class PACKAGE TDummy :  public TComponent, public TClass1
{
public:
    /**
    * Pure virtual VCL style destructor
    *@note Needed to allow WTControlObserver destruction directly (otherwise children destructors
    *      are never called)
    */
    virtual __fastcall ~TDummy()
    {}

    void __fastcall test();
};

And implementation (must be in CPP):

void __fastcall TDummy::test()
{
    int i = 0;
}

I wrote to Embarcadero multiple times, without any luck. We are stuck since our projects can't compile without this.