Re: New cpp0 warning in 3.1 breaks configure (autoconf)

[Loren James Rittle <rittle at latour dot rsch dot comm dot mot dot com>]

>> Why is it on by default?
>
> Nobody knows.

Now Phil, as you know, the reasons for this warning were discussed at
length on the various gcc lists...

>From our current info page, here is the exact reason to avoid
-I/usr/include:

``   It is dangerous to specify a standard system include directory in
     an `-I' option.  This defeats the special treatment of system
     headers .  It can also defeat the repairs to buggy system headers
     which GCC makes when it is installed.''

GCC (preprocessor) developers decided that it seems best to directly
inform the user of the situation instead of silently doing something
screwy.

>> How are one supposed to workaround this in configure scripts?

Well, one does need to understand in detail why configure is checking
``gcc -I/usr/include'' instead of just ``gcc'' to make any proper
change.  Does this really affect every autoconf'd package (on at least
some platforms with at least some version of autoconf, hopefully an
older one)?  I have never seen this problem with autoconf stuff.  Or,
it is related to a local setting of CC or CFLAGS, etc?

Regards,
Loren
-- 
Loren J. Rittle
Senior Staff Software Engineer, Distributed Object Technology Lab
Networks and Infrastructure Research Lab (IL02/2240), Motorola Labs
rittle@rsch.comm.mot.com, KeyID: 2048/ADCE34A5, FDC0292446937F2A240BC07D42763672