Re: master b99ec5d 3/3: Work around __has_attribute bug in clang 3.4

[Eli Zaretskii]

> From: Philipp Stephani <p.stephani2@gmail.com>
> Date: Sat, 23 Jan 2021 17:32:24 +0100
> Cc: Glenn Morris <rgm@gnu.org>, Paul Eggert <eggert@cs.ucla.edu>,
>  Emacs developers <emacs-devel@gnu.org>
> 
> > Apple's clang seems to come with a builtin
> >
> > #define __nonnull _Nonnull
> >
> > which clashes with the the one in lib/cdefs.h. Perhaps we should call it 
> > something else.
> 
> Gnulib should avoid identifiers starting with an underscore, as they
> are reserved for the implementation.

I don't think it can, at least not in general, because Gnulib replaces
some implementations, and this is a kind-of implementation itself.

The rule that you cite is for applications, not for system libraries.