[Bug libstdc++/105580] [12/13 Regression] warning "potential null pointer dereference" raised when using istreambuf_iterator and any "-O" flag

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105580

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I've implemented the suggested changes to istreamubf_iterator and also proposed
them as a resolution for LWG 2366 https://wg21.link/lwg2366