[Voted into the WP at the March, 2011 meeting as part of paper N3262.]

Notes from the November, 2010 meeting:

The consensus of the CWG was to change the behavior so that all classes have a declaration of a copy constructor, but that it is defined as deleted in the cases where the declaration is omitted by the current rules.

It seems odd to have an implicitly declared copy constructor (and the same for the copy assignment operator) if one of the subobjects does not have one. For example,

    struct A {
       A();
       A(A&&);
    };

    struct B: A { };

    B b;
    B b2(b); // error when implicitly defining B(B&), should not be declared

If we don't declare it in that case, we need to decide what happens if one base has only a move constructor and another has only a copy constructor.