MISRA C:2012  Rule-5.4:  (Required)			Macro identifiers shall be distinct

Amplification:

This rule requires that, when a macro is being defined, its name be distinct from:

• the names of the other macros that are currently defined; and
• the names of their parameters.

It also requires that the names of the parameters of a given macro be distinct from each other but does not require that macro parameters names be distinct across two different macros.

The definition of distinct depends on the implementation and on the version of the C language that is being used:

• In C90 the minimum requirement is that the first 31 characters of macro identifiers are significant;
• In C99 the minimum requirement is that the first 63 characters of macro identifiers are significant.

In practice, implementations may provide greater limits. This rule requires that macro identifiers be distinct within the limits imposed by the implementation.

Example Code:

#include "misra.h"
#include "m3cmex.h"

     /* 1234567890123456789012345678901********* Characters */
#define engine_exhaust_gas_temperature_raw egt_r
#define engine_exhaust_gas_temperature_scaled egt_s                     /*      */ /* Non-compliant */

     /* 1234567890123456789012345678901********* Characters */
#define engine_exhaust_gas_temp_raw egt_r
#define engine_exhaust_gas_temp_scaled egt_s                            /*      */ /* Compliant */

No QAC messages cover this rule.

(c) The Motor Industry Research Association, 2012

QA C Source Code Analyser 8.1.2 MISRA C:2012 Compliance Module 1.0 © 2013 Programming Research www.programmingresearch.com

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