[Bug libstdc++/83127] Missing overload for operator << of std::stringstream for old ABI

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83127

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
It links fine on GNU/Linux using a standard start function, int main().