Re: [PATCH 01/10] Add support for GCC-4.5's __builtin_unreachable() to compiler.h

[David Daney]

Geert Uytterhoeven wrote:
> On Fri, Sep 11, 2009 at 17:58, David Daney<ddaney@xxxxxxxxxxxxxxxxxx> wrote:
> > Michael Buesch wrote:
> > > On Friday 11 September 2009 01:56:42 David Daney wrote:
> > > > +/* Unreachable code */
> > > > +#ifndef unreachable
> > > > +# define unreachable() do { for (;;) ; } while (0)
> > > > +#endif
> > > # define unreachable() do { } while (1)
> > >
> > > ? :)
> > Clearly I was not thinking clearly when I wrote that part.  RTH noted the
> > same thing.  I will fix it.
>
> However, people are so used to seeing the `do { } while (0)' idiom,
> that they might miss
> there's a `1' here, not a `0'.
>
> So perhaps it's better to use plain `for (;;)' for infinite loops?

I don't think so.  The only valid token that can follow 'do { } while 
(1)' is ';', any statement may follow 'for (;;)', so there is a greater 
possibility to silently screw things up with the for(;;) form.

David Daney

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