Helps generate a default operator / member function for classes whose components (base classes, data members) have the operator / member function. This is an ugly hack, and would only be worth using in rare circumstances. But it does illustrate that there is a common, underlying introspection / reflection mechanism implicit in the default constructors, destructor, and assignement operators. The ISO C++ Committee is considering adding a default equality operator, that would also use this mechanism. I think it's probably a better course to add some explicit introspection / reflection mechanism that would allow for library implementations of a default equality operator, other comparison operators, hash, endiance swapping and perhaps other members. This is a discussion of one such explicit mechanism:

https://groups.google.com/a/isocpp.org/forum/?fromgroups#!topic/std-proposals/_Pl2_WdSV8k