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

[Jan Beulich <jbeulich@xxxxxxxx>]

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?

> +         - 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?

> +   * - `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?

> +       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

?

Jan