As far as I know, infinite recursion during template instantiation is undefined behavior. Edit: checked iso/iec 14882 (c++03), 14.7.1 Implicit instantiation. §

As far as I know, infinite recursion during template instantiation is undefined behavior. Edit: checked iso/iec 14882 (c++03), 14.7.1 Implicit instantiation. §14 "The result of an infinite recursion in instantiation is undefined".