[Bug preprocessor/78497] compiling with -save-temps adds -Wimplicit-fallthrough warnings

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78497

--- Comment #3 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
One aspect to the problem is the extra warnings you get.  As more and more
projects adopt -Werror by default, it means you get a different error with
-save-temps.  That's bad for users and inconvenient for ourselves.

Now the real kicker is that -save-temps is the standard, recommended way for
users to report bugs.  As preprocessing now discards information that feeds
into compiler decisions, the odds of some other divergence that is more likely
to affect small details in the compilation to the point of no longer triggering
hard-to-hit bugs grows.  That would is a very unfortunate outcome for a problem
that has an easy-ish solution described in the bug report description.