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

[msebor at gcc dot gnu.org]

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

--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
I think the general improvement I'm suggesting is to be able to put the
tilde(s) under or point the caret at any character of the format string,
including either of the two quotes.

It's already possible to underscore the whole format string and point the caret
at any character within in, including the first quote, so it seems natural to
also point the caret at the last quote.