Proposed resolution (May, 2015):

Change Clause 11 [class] paragraph 7 as follows:

...M(X) is defined as follows:

• If X is a non-union class type, the set M(X) is empty if X has no (possibly inherited ( 11.7 [class.derived])) non-static data members; otherwise, it consists of the type of the first non-static data member of X (where said member may be an anonymous union), X₀, and the elements of M(X₀).

• If X is a union type, the set M(X) is the union of all M(U_i) and the set containing all U_i, where each U_i is the type of the ith non-static data member of X.

• If X is an array type with element type X_e, the set M(X) consists of X_e and the elements of M(X_e).

• If X is a non-class, non-array type, the set M(X) is empty.

[Note: M(X) is the set of the types of all non-base-class subobjects that are guaranteed in a standard-layout class to be at a zero offset in X. —end note]