Re: Portability issues with scractch_buffer

[Paul Eggert]

> > My guess is that the preprocessor expands __has_attribute (__fallthrough__) to 
> > 1 but the attribute does not actually work. Is that the case?
>
> has_attribute is indeed 1.
>
> > Looking at the Clang 3.4 source code, I don't see how that could be, as 
> > clang-3.4/include/clang/Basic/Attr.td lists the clang::fallthrough attribute 
> > for CXX11 but not for C. Possibly I'm misunderstanding that file, but just to 
> > check, does your preprocessor version match your compiler version? or are you 
> > compiling with clang++?
>
> No, this is the genuine C compiler of that version.  As provided by Ubuntu.

It turns out that __has_attribute is subtly broken in clang 3.4 and 
earlier; this is documented in the clang 3.5 release notes. I installed 
into Gnulib the attached simple workaround to attempt to work around the 
problem.

This doesn't solve the more-important issue that we have with older 
clang, but one thing at a time.

0001-Port-FALLTHROUGH-to-clang-3.4-and-earlier.patch
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