Re: [PATCH] docs/misra: add rules 10.1 10.2 10.3 10.4

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 25 Aug 2023, Jan Beulich wrote:
> On 24.08.2023 01:14, Stefano Stabellini wrote:
> > --- a/docs/misra/rules.rst
> > +++ b/docs/misra/rules.rst
> > @@ -318,6 +318,58 @@ maintainers if you want to suggest a change.
> >       - An element of an object shall not be initialized more than once
> >       -
> >  
> > +   * - `Rule 10.1 
> > <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_01.c>`_
> > +     - Required
> > +     - Operands shall not be of an inappropriate essential type
> > +     - The following are allowed:
> > +         - Value-preserving conversions of integer constants
> > +         - Bitwise and, or, xor, one's complement, bitwise and assignment,
> > +           bitwise or assignment, bitwise xor assignment (bitwise and, or, 
> > xor
> > +           are safe on non-negative integers; also Xen assumes two's 
> > complement
> > +           representation)
> > +         - Left shift, right shift, left shift assignment, right shift
> > +           assignment (see C-language-toolchain.rst for assumptions on
> > +           compilers' extensions)
> 
> Is "assumptions" the right term here? We don't just assume these are there,
> we actually checked their doc and behavior. Maybe simply "uses of" instead?

yes, I'll use "uses of"


> > +         - Implicit conversions to boolean for logical operators' arguments
> 
> What is "logical operators" here? Perhaps this wants to be "conditionals"
> instead, to cover all of ?:, if(), while(), for() (did I forget any?), of
> which only the first is an operator?

There are also ! || && which are the logical operators

I'll write it as follows:

Implicit conversions to boolean for conditionals (?: if
while for) and logical operators (! || &&)


> > +   * - `Rule 10.3 
> > <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_03.c>`_
> > +     - Required
> > +     - The value of an expression shall not be assigned to an object
> > +       with a narrower essential type or of a dierent essential type
> 
> Nit: ff missing?

yep, thanks


> > +       category
> > +     - Please beware that this rule has many violations in the Xen
> > +       codebase today, and its adoption is aspirational. However, when
> > +       submitting new patches please try to decrease the number of
> > +       violations when possible.
> > +
> > +       gcc has a helpful warning that can help you spot and remove
> > +       violations of this kind: conversion. For instance, you can use
> > +       it as follows:
> > +
> > +       cd xen; CFLAGS="-Wconversion -Wno-error=sign-conversion 
> > -Wno-error=conversion" make
> 
> Maybe slightly shorter as
> 
> CFLAGS="-Wconversion -Wno-error=sign-conversion -Wno-error=conversion" make 
> -C xen
> 
> ?

I'll make the change here and also in the other instance of the same