Re: [XEN PATCH 1/3] x86/emul: define pseudo keyword fallthrough

[Federico Serafini <federico.serafini@xxxxxxxxxxx>]

On 06/11/24 12:22, Jan Beulich wrote:
> On 06.11.2024 10:04, Federico Serafini wrote:
> > The pseudo keyword fallthrough shall be used to make explicit the
> > fallthrough intention at the end of a case statement (doing this
> > through comments is deprecated).
> >
> > Signed-off-by: Federico Serafini <federico.serafini@xxxxxxxxxxx>
> > ---
> >   xen/arch/x86/x86_emulate/x86_emulate.h | 10 ++++++++++
> >   1 file changed, 10 insertions(+)
> When you had asked my privately on Matrix, I specifically said: "Adding
> the pseudo-keyword to x86-emulate.h (not x86_emulate.h) is probably best,
> unless problems with that approach turn up." Even if identical re-
> definitions are deemed fine, I for one consider such bad practice. Yet
> by playing with this file (and outside of any relevant #ifdef) means
> there will be such a re-definition when building Xen itself.
Sorry Jan, I misinterpreted your message.
I tested the definition in the x86-emulate.h and there are no problems.
I will send a V2.


> In fact the patch subject should also already clarify that the auxiliary
> definition is only needed for the test and fuzzing harnesses.
Ok.


> > --- a/xen/arch/x86/x86_emulate/x86_emulate.h
> > +++ b/xen/arch/x86/x86_emulate/x86_emulate.h
> > @@ -23,6 +23,16 @@
> >   # error Unknown compilation width
> >   #endif
> >   
> > +/*
> > + * Pseudo keyword 'fallthrough' to make explicit the fallthrough intention at
> > + * the end of a case statement.
> > + */
> > +#if (!defined(__clang__) && (__GNUC__ >= 7))
> I realize xen/compiler.h has it like that, but may I ask that you omit
> the meaningless outer pair of parentheses?
Ok.

--
Federico Serafini, M.Sc.

Software Engineer, BUGSENG
Ph.D. Student, Ca' Foscari University of Venice