[Bug tree-optimization/100366] spurious warning - std::vector::clear followed by std::vector::insert(vec.end(), ...) with -O2

["msebor at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100366

--- Comment #9 from Martin Sebor <msebor at gcc dot gnu.org> ---
Just to clarify: when I said the warning is justified I meant that there is
nothing in the IL to keep the warning from triggering.  I.e., it works as
designed.  The problem may be solved by optimizing the code better, which might
be possible by enhancing the optimizers or by changing or annotating the
libstdc++ code to enable existing optimizations.  In the latter case it will of
course only help libstdc++ and not other code like it.  A third possibility is
to make the warning itself smarter than the optimizer and figure out the code
is unreachable without its help.