Re: cpplib and a couple others: squelch -pedantic warnings

["Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>]

 > From: Gabriel Dos Reis <gdr@codesourcery.com>
 > 
 > Zack Weinberg <zack@wolery.cumb.org> writes:
 > 
 > [...]
 > 
 > | > However I'm not sure why its necessary to make malloc'ed objects be
 > | > const char *.  Sometimes its done when you share malloc'ed strings and
 > | > "literal" and/or const strings in the same pointer.  IMHO, this is a
 > | > dangerous practice because it leads to strange errors when you
 > | > accidentally free the "literal" string.  Would it be possible to stop
 > | > malloc'ing strings into const char * pointers in cpp without
 > | > de-constifying it too much?
 > | 
 > | Actually, malloced strings are the least of the problem.
 > | 
 > | Most of cpplib's data structures are write-once.  I express that by
 > | building them in non-constant variables, then setting constant
 > | pointers to them.  The compiler can then enforce immutability
 > | everywhere else.  I've found several subtle and dangerous bugs with
 > | this tactic.  But I still need the ability to free those data
 > | structures when I'm done with them.
 > 
 > That is the sort of thing what I'm doing with the diagnostic stuff.
 > I don't find de-constifying the right thing to do, at least not as
 > proposed.
 > -- Gaby

How about providing a cfree() function which does the following:

 > /* Provide a version of `free' which deallocates const pointers.  This
 >    allows one to create immutable objects and free them without
 >    getting warnings from passing a const pointer to free or requiring
 >    one to cast away const-ness which makes gcc -Wcast-qual complain.
 >    You'll still get one cast qual warning right here of course.  */
 > 
 > void cfree(p)
 >      const PTR p;
 > {
 >   free ((PTR) p);
 > }

This would at least consolidate the problem into one warning.  If you
guys agree with this approach, I'll stick it in xmalloc.c/libiberty.h.

		--Kaveh
--
Kaveh R. Ghazi			Engagement Manager / Project Services
ghazi@caip.rutgers.edu		Qwest Internet Solutions