[Bug preprocessor/77672] wrong rich location in warning: writing a terminating nul past the end

[dmalcolm at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77672

--- Comment #5 from David Malcolm <dmalcolm at gcc dot gnu.org> ---
BTW, if you do have a need to send a "print the whole string" request via class
substring_loc, that could be handled by passing in INT_MAX as the idx values,
which will lead to a failure.  (we could make it handle -1 similarly, but
input.c:get_source_location_for_substring currently only checks the upper
bound; it doesn't yet check > 0, but that would be trivial).