[Bug c++/109642] False Positive -Wdangling-reference with std::span-like classes

["carlosgalvezp at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109642

--- Comment #4 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
While I can do that on my own code, I cannot add that suppression on
third-party code, like Eigen (which I also get a lot of false positives in
similar code), even if I include the header via -isystem - since the warnings
are on the client side.

Is this really the expected behavior of a warning belonging to -Wall? Has this
warning been tested on large projects to evaluate the false positive rate?

Would you consider perhaps reducing the scope of the warning in order to reduce
the false positive rate, alternatively move it out of Wall?

It's sad that a lot of work and effort was put into creating this warning and
it will just probably be disabled on most projects. When a tool produces a lot
of false positives, there is high risk that developers stop trusting the tool
and true positives are ignored.