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

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-11-03 14:28:28

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;
};

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

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).