Rule 2.5 unsued macro definition

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sowiso
Posts: 2
Joined: Thu Jun 01, 2017 12:47 pm
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Rule 2.5 unsued macro definition

Post by sowiso » Fri Sep 08, 2017 9:55 am

Hi,

I have the following code:

Code: Select all

cfg.h:
/* uncomment next line if the feature is needed for your project */
/* #define activate_feature */

-----
feature.h:
#ifdef activate_feature

#ifdef protected_feature
/* limited visibility stuff */
[...]
#endif /* protected feature */

#endif /* activate feature */

-----

feature.c:
#define protected_feature

#include "cfg.h"
#include "feature.h"

#ifdef activate_feature
[...]
#endif /* activate feature */

The code is part of a library which is used in various projects which shall be MISRA2012 compliant.
Based on each project a different version of cfg.h is used which configures the project specific needs.
In projects where activate_feature is not defined I always got a claim from my code checking tool that the macro protected_feature is not used.
Is this really a violation of Rule 2.5 or is the code checker wrong?
If it is a violation how to handle code where parts a selected by conditional compiling?

misra-c
Posts: 548
Joined: Thu Jan 05, 2006 1:11 pm

Re: Rule 2.5 unsued macro definition

Post by misra-c » Thu Sep 21, 2017 1:01 pm

The rationale for rule 2.5 is that it is unclear to a reviewer whether an unused macro is intentionally redundant or whether it was left unused by mistake. The example is not compliant with rule 2.5.
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Posted by and on behalf of
the MISRA C Working Group

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