MISRA C:2012 Rule-17.7

Question

I am getting MISRA C:2012 Rule-17.7 violation for below code. I am quite new to C code and MISRA concepts. Any suggestions would be greatly appreciated.

 5277:   Dem_SetEventStatus(Rte_PDAV_DemEvent_DtcC00100_1, EventStatus);
         ^
Msg(7:3200) 'Dem_SetEventStatus' returns a value which is not being used.
MISRA C:2012 Rule-17.7

Answer 1

Background
The Diagnostic Event Manager (Dem) is a Basic Software Module of the AUTOSAR Diagnostic Services. Relevant errors are reported either from Application Layer (resp. SW-C) or Basic Software Modules (BSWM).

• BSWs report the new status of the event with the Dem_ReportErrorStatus API
• SWCs report the new status of the event with the Dem_SetEventStatus API (through the RTE)

The Diagnostic Event Manager (Dem) handles and stores the diagnostic events detected by diagnostic monitors in both Software Components (SW-Cs) and Basic Software Modules (BSWM). The stored event information is available via an interface to other BSW modules or SW-Cs.

Function Dem_SetEventStatus()
This function has a prototype of:

Std_ReturnType Dem_SetEventStatus(
Dem_EventIdType EventId,
Dem_EventStatusType EventStatus
)

Note the return type is Std_ReturnType - which returns either E_OK or E_NOT_OK

MISRA C:2012 Rule 17.7
MISRA C:2012 Rule 17.7 requires that you do something with the values returned from a (non- void ) function...

The function is telling you something... it has either succeeded E_OK or failed E_NOT_OK - ignoring this information is probably not a good idea.

If you genuinely want to ignore it, then stick in a (void) cast - but make sure you add a good clear rationale for doing so.

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Answer 2

Dem_SetEventStatus is returning a standard return type with some values (eg, EOK and E_NOT_OK )

If the API was successful in doing what it was supposed to do then you will get E_OK and if some error pops up then you get E_NOK

With an indication of error, you may want to retry setting the event or just ignore depending on your strategy to handle the functionality.