Re: glibc and cdefs.h

[Bruno Haible]

Hi Paul,

> I would like to keep Gnulib cdefs.h in sync with glibc as much as 
> possible, and installed the attached.

The __nonnull handling here is more risky than my patch. But it works on
FreeBSD 11.

> I hope this sort of thing is a one-off.
> 
> I guess you're suggesting two include files? config.h has to come first, so 
> there'd be another include file (let's say, configlast.h) that would come 
> last. 
> I think something like that would work, though it would complicate the 
> shared-with-glibc files a bit more, and even then it wouldn't be 100% 
> reliable 
> because system include files could define macros that are expanded after 
> configlast.h is included.
> 
> If this is the only such problem we run into I'm not sure it's worth the 
> hassle 
> of having multiple includes. If we run into more such problems, we can keep 
> this 
> idea in reserve, though.

I would find it more reliable to just stay away from using symbols that start
with '__', because that is the "implementation's" namespace, i.e. partially the
operating system's namespace and partially the compiler's namespace. That is,
I would suggest to use symbols prefixed with '_GLIBC_' where glibc uses symbols
prefixed with '__'.

But I understand that this would make the sync with glibc more complicated
(although it could be automated: "sed -e 's/_GLIBC_/__/g'"), and you are doing
the work.

Bruno