Re: [PATCH] docs/misra: document gcc-specific behavior with shifting signed integers

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 21 Aug 2023, Jan Beulich wrote:
> On 19.08.2023 02:33, Stefano Stabellini wrote:
> > From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> > ---
> > Changes in v2:
> > - use "shift" instead of << or >>
> > - use All Architectures (I haven't changed all the other instances of
> > x86/arm in the file yet)
> > ---
> >  docs/misra/C-language-toolchain.rst | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/docs/misra/C-language-toolchain.rst 
> > b/docs/misra/C-language-toolchain.rst
> > index 785aed1eaf..f5ca7bd2c8 100644
> > --- a/docs/misra/C-language-toolchain.rst
> > +++ b/docs/misra/C-language-toolchain.rst
> > @@ -200,6 +200,12 @@ The table columns are as follows:
> >       - ARM64, X86_64
> >       - See Section "6.29 Designated Initializers" of GCC_MANUAL
> >  
> > +   * - Signed shift acts on negative numbers by sign extension
> > +     - All architectures
> > +     - See Section "4.5 Integers" of GCC_MANUAL. As an extension to the
> > +       C language, GCC does not use the latitude given in C99 and C11
> > +       only to treat certain aspects of signed shift as undefined.
> 
> I'm sorry, but that's still not what the doc says. Replacing << and >> by
> "shifts" was imo wrong. What's needed instead is that either this is split
> into two top-level bullet points (one for << and one for >>), or the first
> sub-bullet-point (which acts as kind of the title) be generalized, with
> the << and >> details fully moved to the "explanatory" sub-bullet-point.

I think I got your point now