[ 2015-03-22, Jens Maurer responses to Cologne discussion ]

A library implementation could provide a partial specialization for is_trivially_copyable<atomic<T>>, to ensure that any such type query would return false.

Assuming such a specialization would be provided, how could a conforming program observe that per language rules an atomic specialization would actually be trivially copyable if there is no way to call the (deleted) copy constructor or copy assignment operator?

The sole effect of the suggested addition of the constraining sentence is that it would make a user program non-conforming that attempts to invoke memcpy (and the like) on atomic types, since that would invoke undefined behaviour.