Notes from the April, 2005 meeting:

The question in the original example was whether there should be an error, even though the uninstantiable template was not needed for calling the best-matching function. The broader issue is whether a user would prefer to get an error or to call a “worse” non-template function in such cases. For example:

    template<typename T> void f(T);
    void f(int);
    void g() {
        enum E { e };
        f(e);    // call f(int) or get an error?
    }

It was observed that the type deduction rules are intended to model, albeit selectively, the other rules of the language. This would argue in favor of the second approach, a type-deduction failure, and the consensus of the group was that the incremental benefit of other approaches was not enough to outweigh the additional complexity of specification and implementation.