[cpp-threads] RE: volatile, memory models, threads

[Peter Dimov]

Nick Maclaren wrote:

> ALL that is needed to allow an implementation to support any POD type
> as atomic is to allow it to add a lock flag to that object, but that
> means allowing an atomic type to be of different size to the
> unqualified type.  This is already allowed in one section, except
> that the ability to lose qualifiers makes it unimplementable!

You keep saying that, but it simply isn't true. Objects of cv-qualified 
types have the same representation and alignment as objects of the 
cv-unqualified types (3.9.3/1), and representation in this context includes 
size (3.9/4). And of course the ability to _add_ qualifiers, which is a 
pretty basic part of the language (char* to char const*), also requires it, 
not only the ability to lose them.