Re: __user annotations

[Daniel Jacobowitz <dan@debian.org>]

On Fri, Jun 06, 2003 at 05:43:58PM -0700, Linus Torvalds wrote:
> 
> On Sat, 7 Jun 2003, Paul Mackerras wrote:
> > Linus Torvalds writes:
> > 
> > > You can get check from
> > > 
> > > 	bk://kernel.bkbits.net/torvalds/sparse
> > 
> > Is that up to date?  I cloned that repository and said "make" and got
> > heaps of compile errors.  First there were a heap of warnings like
> > this:
> 
> You need to have a modern compiler. The "heaps of errors" is what you get 
> if you use a stone-age compiler that doesn't support anonymous structure 
> and union members or other C99 features.
> 
> Gcc has supported them since some pre-3.x version (which is pretty late,
> since they've been around in other compilers for much longer). They are a
> great way to make readable data structures that have internal structure
> _without_ having to have that structure show up unnecessarily in usage.

Actually, I believe they are an extension, which GCC honors.  Unnamed
structures in standard C99 are actually declaring an unnamed type, not
an unnamed member.  Try it:

     struct {
       int a;
       union {
         int b;
         float c;
       };
       int d;
     } foo;

int bar()
{
  return foo.a + foo.d + foo.b;
}


With -std=c99, the reference to foo.b is an error; with -std=gnu99 or
-std=gnu89, it is accepted.


I don't know why they were getting rejected for Paul, though.  Did you
have GNU set to -ansi mode?

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer