Re: Those obnoxious "mktemp is not safe" warnings

["Joseph S. Myers" <jsm28 at cam dot ac dot uk>]

On Wed, 21 Mar 2001, Zack Weinberg wrote:

> I'd also point out that we cannot rely on the library to define NULL
> as ((void *) 0) - it is often 0, and *required* to be plain 0 in
> C++ (yes, I know about __null)...
> 
> Hm, maybe we should have __null in C?

I don't think we really want the additional complexity of __null.

One thing I wondered about: a natural (and I think previously discussed)
extension of the idea of Marc Espie's __attribute__((__nonnull__)) patch
would be to check calls to function such as execl that require
NULL-terminated argument lists.  It was noted on the Austin Group list
that one of the Austin Group drafts contained defective examples using
NULL (not cast to (char *) as required).  In principle one might check for
and warn about the use of uncast NULL in such a case.  But both ways of
doing this - a magic __null, or making it possible to use integrated CPP
to ask "is this argument the result of expanding a definition of NULL that
was defined in a system header" [so unportable to systems that use plain 0
even if that header used ((void *)0)], seem to involve excess complication
for the limited gain.  (However, the basic checking for execl-like
functions that they get a series of char * arguments, made up of the
correct number of (char * or void *) NULL terminated lists, would make
sense to implement.)

-- 
Joseph S. Myers
jsm28@cam.ac.uk