On Mon, 4 Mar 2024, Jan Beulich wrote: > On 02.03.2024 02:37, Stefano Stabellini wrote: > > On Fri, 1 Mar 2024, Jan Beulich wrote: > >> On 29.02.2024 23:57, Stefano Stabellini wrote: > >>> On Thu, 29 Feb 2024, Nicola Vetrini wrote: > >>>> MISRA C Rule 20.7 states: "Expressions resulting from the expansion > >>>> of macro parameters shall be enclosed in parentheses". Therefore, some > >>>> macro definitions should gain additional parentheses to ensure that all > >>>> current and future users will be safe with respect to expansions that > >>>> can possibly alter the semantics of the passed-in macro parameter. > >>>> > >>>> No functional change. > >>>> > >>>> Signed-off-by: Nicola Vetrini <nicola.vetr...@bugseng.com> > >>> > >>> Reviewed-by: Stefano Stabellini <sstabell...@kernel.org> > >> > >> You did see the discussion on earlier patches, though? I don't think > >> any of the parentheses here are needed or wanted. > > > > We need to align on this. Currently if we go by what's written in > > docs/misra/deviations.rst, then rhs should have parentheses. > > Quoting the actual patch again:
[...] > What rhs are you talking about in light of this change? The only rhs I > can spot here is already parenthesized. Yes you are right. I replied here as an overall comment about our approach to 20.7, although this patch is not a good example. My reply was meant in the context of https://marc.info/?l=xen-devel&m=170928051025701 > > Can we safely claim that rhs parentheses are never needed? If so, then > > great, let's add it to deviations.rst and skip them here and other > > places in this patch series (e.g. patch #8). When I say "never" I am > > taking for granted that the caller is not doing something completely > > unacceptably broken such as: > > > > WRITE_SYSREG64(var +, TTBR0_EL1) > > I'm afraid I can't associate this with the patch here either. Instead in > the context here a (respective) construct as you mention above would simply > fail to build. Fair enough it will break the build. I was trying to clarify that when I wrote "the rhs parentheses are never needed" I meant "never" within reason. One can always find ways to break the system and I tried to make an example of something that for sure would break rhs or lhs without parentheses. I meant to say, if we don't account for exceptionally broken cases, can we safety say we don't need parentheses for rhs? > > If we cannot generically claim that rhs parentheses are never needed, > > then I don't think we should make any exceptions. We should add them here > > and everywhere else. It should be easy to write a macro or review a > > patch with a macro from someone else, and making special exception makes > > it more difficult for everyone.
