https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63698
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> --- Yes, it looks like we also need: --- a/libstdc++-v3/include/bits/stl_tree.h +++ b/libstdc++-v3/include/bits/stl_tree.h @@ -423,6 +423,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION while (_M_nodes->_M_right) _M_nodes = _M_nodes->_M_right; + if (_M_nodes->_M_left) + _M_nodes = _M_nodes->_M_left; } } else // __node is on the left.