Re: emacs' turn: remove useless if-before-free tests

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

>>>>> On Mon, 02 Jun 2008 11:05:55 +0900, Miles Bader <miles.bader@necel.com> said:

>> I guess the acceptance of NULL for `free' in POSIX is the
>> reflection of the fact that `malloc' may return NULL.  If so, we
>> could take a different policy for `xfree', i.e., abort if NULL,
>> because `xmalloc' may not return NULL unlike malloc.  This may help
>> us detect the behavior that is different from programmer's
>> intention.

> xmalloc can return NULL.

IIUC, only when the SIZE argument is 0.  I think many programmers have
never cared about the NULL-check of the return value of xmalloc where
they are sure that its argument is positive.  Also we could make
xmalloc to return a non-NULL value for the case SIZE==0.

> I think xmalloc and xfree should act as much like posix malloc/free
> as possible, modulo the error-handling behavior of xmalloc.  That
> will be the least surprising to programmers using them.  Indeed, we
> can make them act like the posix function even on systems whose
> native malloc is less so.

That would be one policy.  What I said is just another possible policy
that could make use of the explicit distinction between `if (p) xfree
(p)' and `xfree (p)' programmers have been made rather than losing
such information just for cleanup.

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp