[Bug c++/58063] default arguments evaluated twice per call

[fanael4 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58063

Fanael <fanael4 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fanael4 at gmail dot com

--- Comment #10 from Fanael <fanael4 at gmail dot com> ---
My attempt at reducing:

struct basic_ios
{
  virtual ~basic_ios() {}
  bool operator!() const { return false; }
};

struct ostream : virtual basic_ios
{
  ostream() {}
  ~ostream() {}
private:
  ostream(const ostream&);
  ostream& operator=(const ostream&);
};

ostream& operator<<(ostream& os, const char* s) {
  __builtin_printf("%s", s);
  return os;
}

ostream cout;

void f(bool x = !(cout << "hi!\n")) {
  __builtin_printf("%d\n", static_cast<int>(x));
}

int main() {
  f();
}

Seems like virtual inheritance is the culprit.