[Bug libstdc++/80331] unused const std::string not optimized away

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80331

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
With -std=c++20 -O2 I get better code than just -std=c++17 -O2:
  _34 = operator new (24);
  __builtin_memcpy (_34, "a                      ", 23);
  MEM[(char_type &)_34 + 23] = 0;
  operator delete (_34, 24);

That is all I think due to what is referenced in PR 86590.