[Doxygen-users] dot tool and tagfiles -> bug?

[Matthias W. <ma...@fy...>]

Dear doxygen community,
I use doxygen to document my libraries. I have two separate libraries A and B, where B depends on A like so:

    //library A
    struct A::aAnimal{};
    struct A::Dog : public A::aAnimal{};
    struct A::Snake : public A::aAnimal{};


----------


    //library B
    struct B::Cat : public A::aAnimal{};

Assume all of the classes documented with doxygen and both library A and B have a separate Doxyfile. For generating the documentations I do the following:
1. Generate tag file for library A
2. Generate tag file for library B
3. Generate the documentation for A using B's tagfile
4. Generate the documentation for B using A's tagfile

Now the dot tool creates the graph { aAnimal <- Dog; aAnimal <- Snake } in the documentation in A. However, I expected the graph { aAnimal <- Dog; aAnimal <- Snake; aAnimal <- Cat; }, i.e. by passing B's tagfile to A I thought that the dot tool realizes that there is an additional derivation of aAnimal in B.
I inspected the tagfiles and realized that the tagfile for B is missing the line

<base>A::aAnimal</base>

in the Cat compound. Adding the line makes it work as expected.
So my question is:
- is this a bug?
- or is there a deeper reason not to include this information in the tagfile for B?
with best regards
Matthias