This caused a new regression for:
std::forward_list<std::string> flst;
std::forward_list<std::string>::iterator flstiter0;
// { dg-final { note-test flstiter0 {non-dereferenceable iterator for
std::forward_list}} }
$1 = {_M_node = 0x0}
got: $1 = {_M_node = 0x0}
FAIL: libstdc++-prettyprinters/debug_cxx11.cc print flstiter0
