Re: sequence of inheritance from virtual base class?

I have a problem with the sequence of inheritance:

    // header1.h
    class Base {
     public:
       Base() {}
       virtual ~Base() {}
       virtual void foo() = 0;
    };

    // header2.h
    #include "header1.h"
    class Unrelated1 {};
    class Unrelated2 {};

    class Derived1 : public Base, public Unrelated1, public Unrelated2 {
    public:
       Derived1() {}
       ~Derived1() {}
       void foo() {}
    };

    class Derived2 : public Unrelated1, public Unrelated2, public Base {
    public:
       Derived2() {}
       ~Derived2() {}
       void foo() {}
    };

    // main.cc
    // g++ -o main main.cc
    #include "header2.h"

    int main() {
       Derived1 d1;
       Derived2 d2;
       d1.foo(); // ok
       d2.foo(); // crashes in big app
    }

The problem seems to be the sequence of inheritance: if I inherit
from 'Base' first (Derived1), the code seems to run ok. If I
inherit from 'Base' last (Derived2), the code crashes reliably at
runtime in a seemingly unrelated code position (other class, other
function, but always the same).

The crash happens when Derived2 comes from one shared lib, Derived1
from another. Calling a non-virtual function in Base seems ok, the
crash happens only when calling a virtual function in Base, so it
looks to me like a wrong lookup in the virtual function table.