[Moved to DR at 4/02 meeting.]

Proposed resolution (04/01):

1. In 9.4 [dcl.init] paragraph 14, insert the following after "the call initializes a temporary of the destination type":

   The temporary is an rvalue.

2. In 14.2 [except.throw] paragraph 3, replace

   The temporary is used to initialize the variable...

   with

   The temporary is an lvalue and is used to initialize the variable...

(See also issue 84.)

Is the temporary created during copy-initialization of a class object treated as an lvalue or an rvalue? That is, is the following example well-formed or not?

    struct B { };
    struct A {
        A(A&);    // not const
        A(const B&);
    };
    B b;
    A a = b;

According to 9.4 [dcl.init] paragraph 14, the initialization of a is performed in two steps. First, a temporary of type A is created using A::A(const B&). Second, the resulting temporary is used to direct-initialize a using A::A(A&).

The second step requires binding a reference to non-const to the temporary resulting from the first step. However, 9.4.4 [dcl.init.ref] paragraph 5 requires that such a reference be bound only to lvalues.

It is not clear from 7.2.1 [basic.lval] whether the temporary created in the process of copy-initialization should be treated as an lvalue or an rvalue. If it is an lvalue, the example is well-formed, otherwise it is ill-formed.