Re: remove predefinitions from cpp/cpplib

[Marc Espie <espie at tetto dot liafa dot jussieu dot fr>]

Yet another discussion I have missed... until the patch was in.

No, this does not work at all for me.  The problem is that -undef is
part of the visible interface of cpp, as documented in the man page
AND the texinfo documentation.

In fact, I noticed it while compiling xlint, a lint program which uses
cpp -undef to get `clean' definitions.

I wonder why -undef is to go completely away.  I can understand not 
wanting to couple gcc and cpp that tightly there, but cpp is sometimes
used as an independant program.   The reason is not apparent in your
patch and the corresponding (very short) discussion.  If there is
discussion elsewhere, I'd like to get a reference to it, *please*.


Couple of suggestions:

- since cccp is to go away, why isn't -undef simply deprecated there ?
- breaking old things is evil, removing -undef from cccp without 
updating neither the help message, nor the man page nor the texinfo 
documentation is really a bad thing.  Heck, it could *AT LEAST* say
`use -A- to get a similar effect instead'.

- as for that matter, -A- does not even show up in neither cpplib nor
cccp help message, and is very *easy* to miss in the man page and
texinfo documentation...

- patches that change visible behavior should update the corresponding
documentation as well...   this is the way we got into messes with 
extended asm and register clobbers, remember ?