[Bug c/78989] Missing -Waddress warning

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78989

--- Comment #3 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
Looking at the PRs you filed about the locations (PR78987 and PR78988), perhaps
the best approach here is for the location of the warning to be either this:

return (asan_poison_variables &&  
        ~~~~~~~~~~~~~~~~~~~~~~^~
# 6 "gimplify.cpp" 3 4
                              __null
                              ~~~~~~
                                  );

or this:

return (asan_poison_variables &&  
        ~~~~~~~~~~~~~~~~~~~~~~~~
# 6 "gimplify.cpp" 3 4
                              __null
                              ^~~~~~
                                  );

i.e. for the location to be a range starting at the LHS start, finishing at the
RHS finish, with the caret at either the && or the RHS...

...and then for in_system_header_at to only reject the warning if *all* of the
range of the location is fully within a system header, rather than just
partially within a header?