Re: [Bug-gnulib] xalloc: add xstrndup

[Simon Josefsson]

Paul Eggert <address@hidden> writes:

> It's a bit tricky; let me try to explain better.

This was a good explanation, perhaps it would be useful to add
something like it to gnulib/README?  I'm sure at least I'll need to
re-read it again when considering what can safely be included.

> We decided to assume a freestanding C89 compiler so that we could
> assume <limits.h>, <stdarg.h>, and <stddef.h>; many of the modules had
> things like HAVE_LIMITS_H that weren't necessary.
>
> I was dubious about assuming all the hosted headers, since I know that
> many older hosts lack some of them.  However, as a practical matter,
> several gnulib modules already assumed some of the hosted headers
> (e.g., <errno.h>) and there's no practical problem with this, as these
> headers have always been in all our porting targets.  (Similarly, many
> modules assume <sys/types.h> even though it's not even in C99; that's
> OK since <sys/types.h> has been around nearly forever.)
>
> <string.h> and <stdlib.h> were more problematic.  They are not in Unix
> Version 7, so they weren't universally available on ancient hosts.
> However, they are both in SunOS 4 (the oldest platform still in
> relatively-common use) so I think it's OK to assume them now, even if
> their contents may not conform to the standard.  And some gnulib
> modules (e.g., argmatch) already assumed both, and nobody was
> complaining about them, so it seems OK to assume the existence of
> <string.h> and <stdlib.h>.
>
> Even if the include files exist, they may not conform to the C
> standard.  However, GCC has a "fixincludes" script that attempts to
> fix ANSI-conformance problems.  It is a bit of a hack, but I think we
> can probably get away with assuming conformance to C89 or better in
> <string.h> and <stdlib.h>, and ask people to use GCC (or fix their
> include files manually) if they are on ancient hosts.
>
>
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