Re: [boost] [serialization] patch for portable_binary_oarchive.hpp

From: David Abrahams (dave_at_[hidden])
Date: 2007-11-03 19:39:29

on Sat Nov 03 2007, "Peter Dimov" <pdimov-AT-pdimov.com> wrote:

> David Abrahams:
>
>>> (A reinterpret_cast<char*>( p ) is indirectly required to work when
>>> p is a pointer to a class type,
>>
>> Where does the standard say that, and what do you mean by "work?"
>
> Consider this code:
>
> class X;
>
> char * f( X * p )
> {
>     return reinterpret_cast<char*>( p );
> }
>
> This must give you a char* pointing to the first byte of *p because X's 
> definition may be
>
> struct X
> {
>     char v;
> };

Any POD struct will do.

> and the standard requires a reinterpret_cast to yield a pointer to
> the first element (9.2/17).

Nice.

> Because of ODR, the complete type case must be compiled in the same
> way, even when X happens to not have a first member of type char
> (link-time code generation aside).

Right.

OK, then, look for a core issue from me.  It's ridiculous that
reinterpret_cast should be defined to be so close to what everyone
thinks it is, and yet, not quite.

-- 
Dave Abrahams
Boost Consulting
http://www.boost-consulting.com