[Bug c++/103534] [12 regression] Spurious -Wstringop-overflow warning with std::string concatencation

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103534

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
Created attachment 51970
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51970&action=edit
libstdc++ fix