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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2 2/3] docs/misra/rules.rst: add rule 5.5
On 04.03.2024 14:31, Federico Serafini wrote: > On 01/03/24 09:06, Jan Beulich wrote: >> On 01.03.2024 00:28, Stefano Stabellini wrote: >>> On Wed, 14 Feb 2024, Federico Serafini wrote: >>>> On 14/02/24 14:15, Jan Beulich wrote: >>>>> On 14.02.2024 12:27, Federico Serafini wrote: >>>>>> On 14/02/24 09:28, Jan Beulich wrote: >>>>>>> On 13.02.2024 23:33, Stefano Stabellini wrote: >>>>>>>> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx> >>>>>>>> --- >>>>>>>> docs/misra/rules.rst | 6 ++++++ >>>>>>>> 1 file changed, 6 insertions(+) >>>>>>>> >>>>>>>> diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst >>>>>>>> index c185366966..931158b354 100644 >>>>>>>> --- a/docs/misra/rules.rst >>>>>>>> +++ b/docs/misra/rules.rst >>>>>>>> @@ -181,6 +181,12 @@ maintainers if you want to suggest a change. >>>>>>>> headers (xen/include/public/) are allowed to retain longer >>>>>>>> identifiers for backward compatibility. >>>>>>>> + * - `Rule 5.5 >>>>>>>> <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_05.c>`_ >>>>>>>> + - Required >>>>>>>> + - Identifiers shall be distinct from macro names >>>>>>>> + - Clashes between function-like macros and non-callable entities >>>>>>>> + are allowed. The pattern #define x x is also allowed. >>>>>>> >>>>>>> Just for me to know what exactly is covered (hence also a question >>>>>>> to Roberto as to [to be] implemented Eclair behavior): Even when >>>>>>> the above would be sufficient (and imo better) people frequently >>>>>>> write >>>>>>> >>>>>>> #define a(x, y) b(x, y) >>>>>>> >>>>>>> which, transformed to the specific case here, would then be >>>>>>> >>>>>>> #define a(x, y) a(x, y) >>>>>>> >>>>>>> I'd assume such ought to also be covered, but that's not clear >>>>>>> from the spelling above. >>>>>> >>>>>> I list what happens in some different situations, >>>>>> then we can find the right words for the documentation and/or >>>>>> refine the configuration: >>>>>> >>>>>> If you >>>>>> #define x x >>>>>> and then use `x' as identifier, >>>>>> the resulting violation is deviated (allowed pattern). >>>>>> >>>>>> If you >>>>>> #define a(x, y) a(x, y) >>>>>> and then use `a' as identifier for a non-callable entity, >>>>>> the resulting violation is deviated (no clash with non-callable >>>>>> entities). >>>>>> If you use identifier `a' for a callable entity, the resulting violation >>>>>> is reported: the allowed pattern covers only macros expanding to their >>>>>> own name, in this case the macro name is considered to be >>>>>> `a' only, not a(x, y). >>>>>> >>>>>> If you >>>>>> #define a(x, y) b(x, y) >>>>>> and then use `a' as identifier for a non-callable entity, >>>>>> the resulting violation is deviated (no clash with non-callable >>>>>> entities). >>>>> >>>>> I'm afraid I don't see what violation there is in this case, to >>>>> deviate. As a result I'm also not sure I correctly understand the >>>>> rest of your reply. >>>> >>>> #define a(x, y) b(x, y) >>>> >>>> int a; // Violation of Rule 5.5. >>>> >>>> The macro name `a' that exist before the preprocessing phase, >>>> still exists after the preprocessing phase as identifier for the integer >>>> variable and this is a violation. >>>> >>>>>> If you use `a' as identifier for a callable entity, >>>>>> this is not a violation because after the preprocessing phase, >>>>>> identifier `a' no longer exists. >>>> I correct myself: >>>> if you use `a' as identifier for a *function*, >>>> it is not a violation because after the preprocessing phase >>>> the identifier `a' no longer exists, for example: >>>> >>>> #define a(x, y) b(x, y) >>>> >>>> void a(int x, int y); // Ok. >>> >>> Federico, do you have a better wording suggestion for this rule? >>> >>> Jan, any further requests here? What would you like to see as next step? >> >> A more concise wording proposal would probably help. > > What do you think about: > > diff --git a/docs/misra/rules.rst b/docs/misra/rules.rst > index 1e134ccebc..a975b9a85f 100644 > --- a/docs/misra/rules.rst > +++ b/docs/misra/rules.rst > @@ -181,6 +181,13 @@ maintainers if you want to suggest a change. > headers (xen/include/public/) are allowed to retain longer > identifiers for backward compatibility. > > + * - `Rule 5.5 > <https://gitlab.com/MISRA/MISRA-C/MISRA-C-2012/Example-Suite/-/blob/master/R_05_05.c>`_ > + - Required > + - Identifiers shall be distinct from macro names > + - Macros expanding to their own name are allowed (e.g., #define x x). > + Clashes between names of function-like macros and identifiers of > + non-callable entities are allowed. Imo that still leaves open e.g. the #define a(x, y) a(x, y) case: Permitted ("own name") or not permitted ("a" pretty clearly is expected to be a callable entity here, besides being a function-like macro)? Jan
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