Re: [PATCH v2] docs/misra: add rules 10.1 10.2 10.3 10.4

[Bertrand Marquis <Bertrand.Marquis@xxxxxxx>]

Hi Stefano,

> On 25 Aug 2023, at 23:48, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:
> 
> From: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> 
> 10.1 with several caveats, described in the notes.
> 10.3 and 10.4 as "aspirational" guidelines, as clarified in the notes.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>

Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>

Cheers
Bertrand

> ---
> v2:
> - typo fix
> - Implicit conversions to boolean for conditionals and logical operators
> - make -C xen
> ---
> docs/misra/rules.rst | 53 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 53 insertions(+)
> 
> diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst
> index db30632b93..34916e266a 100644
> --- a/docs/misra/rules.rst
> +++ b/docs/misra/rules.rst
> @@ -310,6 +310,59 @@ 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 uses of
> +           compilers' extensions)
> +         - Implicit conversions to boolean for conditionals (?: if while
> +           for) and logical operators (! || &&)
> +
> +   * - `Rule 10.2 
> <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_02.c>`_
> +     - Required
> +     - Expressions of essentially character type shall not be used
> +       inappropriately in addition and subtraction operations
> +     -
> +
> +   * - `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 different essential type
> +       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:
> +
> +       CFLAGS="-Wconversion -Wno-error=sign-conversion 
> -Wno-error=conversion" make -C xen
> +
> +   * - `Rule 10.4 
> <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_10_04.c>`_
> +     - Required
> +     - Both operands of an operator in which the usual arithmetic
> +       conversions are performed shall have the same essential type
> +       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: arith-conversion. For instance, you
> +       can use it as follows:
> +
> +       CFLAGS="-Warith-conversion -Wno-error=arith-conversion" make -C xen
> +
>    * - `Rule 12.5 
> <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_12_05.c>`_
>      - Mandatory
>      - The sizeof operator shall not have an operand which is a function
> -- 
> 2.25.1
>