[Bug c++/67650] undef reference with -fdevirtualize

[vincent.lextrait at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67650

--- Comment #10 from Vincent <vincent.lextrait at gmail dot com> ---
Additionally, in the snippet:

template <typename RC>
struct EN: public RE<int>
{
  EN(::std::string){}
  void rp(){}
};

If you replace ::std::string by const char*, the problem disappears.
More generally, essentially any simplification of the code, unrelated to
virtuals, makes the problem disappear.