John Potter wrote:

> struct B { int b; };
> struct D : B { int d; };
> struct F { B fb; D fd; };
>
> B b;
> D d;
> F f;

> B F::* fbp(&F::fd);            // Builder rejects, egcs accepts

> Hopefully someone knowledgable will give a better answer to the question

not me !

> of why the conversion you want is not listed in chapter 4.  If nothing
> happens, reword the question and post to comp.std.c++.

This conversion is at the same time type safe and
implementable: a pointer to member is an offset (and
perhaps other informations), so you just have to apply
the delta between B and D.

Also the cast in the reversed direction should be allowed
as a static_cast<D F::*> (B F::*).

I have never understoud the reasons (if there are any)
why it isn't allowed.

--

Valentin Bonnard                mailto:bonnardv@pratique.fr
info about C++/a propos du C++: http://pages.pratique.fr/~bonnardv/

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