[Bug c++/78420] std::less is not a total order with -O2 enabled

[tomaszkam at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78420

--- Comment #4 from Tomasz Kamiński <tomaszkam at gmail dot com> ---
Oh, you mean that compiler is not allowed to turn comparison of p == b into
false at compile time, using 5.10 [expr.eq] p2.1? 

Some reference from clang: https://llvm.org/bugs/show_bug.cgi?id=13507. Note
that I am unable to reproduce problem on clang.