Proposed resolution:

The wording refers to N3126.

Change 20.8.2 [func.require]/1 as indicated:

1 Define INVOKE(f, t1, t2, ..., tN) as follows:

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• t1.*f when N == 1 and f is a pointer to member data of a class T and t1 is an object of type T or a reference to an object of type T or a reference to an object of a type derived from T;
• (*t1).*f when N == 1 and f is a pointer to member data of a class T and t1 is not one of the types described in the previous item;
• ...