Rationale:

Infinite recursion is to be expected: users who set the terminate handler to terminate are explicitly asking for terminate to call itself.

According to section 18.7.3.3 of the standard, std::terminate() is supposed to call the terminate_handler in effect immediately after evaluating the throw expression.

Question: what if the terminate_handler in effect is itself std::terminate?

For example:

  #include <exception>

  int main () {
      std::set_terminate(std::terminate);
      throw 5;
      return 0;
  }

Is the implementation allowed to go into an infinite loop?

I think the same issue applies to std::set_unexpected.