>I guess we should use the CEDET infrastructure for that (which would
>also make it possible to scan files which aren't currently visited).

Indeed, I tried CEDET for several years but it always have problems here
or there. After I patch this, that failed.. My embedded system C++ code
contains some non-standard extensions that always causing CEDET
fail so I decide to go hideif solution since it's much smaller :-) and does
not that much rely on the previous parsing contexts to continue parsing.

>But I guess for now we can try your "quick&dirty" solution of making the
>settings global.

I got no better idea but providing one more custom option for that.
Personally I always open different Emacs for different projects with
each its own local session/desktop/... settings; while leaving emacs
server for other general purpose use.

>This does not use the commit history.  Instead it kind of "creates
>a brand new and clean history".

I see. After some thoughts it's still worthwhile even if I do the
cherry-picking
since I've been troubled by those kind of complicate nested #if..#endif
for years and I believe a lot others should have similar problems too.

By the way, what "certification" (sorry that I can't think of a better
word)
is required to be able to commit code directly into the main Emacs
repository (or a branch)? I'm currently working on auto *.h scanning
for hideif.el in my spare time. Maybe there will be more updates some
weeks/months later.

I'll send out two or three patches when I completed the splitting.

Best regards,
Luke Lee