_Rb_tree::erase(const _Key* __first, const _Key* __last)

[Jonathan Wakely]

Is this function an extension?

  template<typename _Key, typename _Val, typename _KeyOfValue,
           typename _Compare, typename _Alloc>
    void
    _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>::
    erase(const _Key* __first, const _Key* __last)
    {
      while (__first != __last)
	erase(*__first++);
    }

It's not in the SGI STL documentation, but it's been in our
implementation since Benjamin added that file, in rev 36723.

Should we keep it? There doesn't seem to be any way to call it,
because it's only on the _Rb_tree class, so there's no public member
of std::{,multi}{map,set} that can be used to call it.