Re: [boost] [type_traits] Need help with an - unfixable? - issue

Subject: Re: [boost] [type_traits] Need help with an - unfixable? - issue
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2009-12-08 11:34:19

John Maddock wrote:
>
> This issue just came in: https://svn.boost.org/trac/boost/ticket/3730
>
> Reduced to the test case below, and I can't see a way to fix this at
> present, anyone any bright ideas?

In case the problem is not clear to anyone...

[extra declarations/definitions removed to focus on virtual inheritance]

> class base {
> public:
>     virtual void method1() = 0;
> };
>
> class derived1 : virtual public base {
> };
>
> class derived2 : virtual public base {
> };
>
> class intermediate : public derived1, public derived2 {
> public:
>     intermediate(int i) : base(i) {}
>
>     void method1();
> };
>
> class final : public intermediate {
> public:
>     final(int i) : base(i) {}
> };

Both intermediate and final have a unique override of method1().

> struct X : final, virtual intermediate
> {
> };

X has two intermediate subobjects, so there's no unique override of method1().

The question, then, is how to change is_virtual_base_of to account for this situation.  That will require more thought.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer, Core Software      using std::disclaimer;
Susquehanna International Group, LLP  http://www.sig.com

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