MISRA C:2012 Rule 2.5

A project should not contain unused macro definitions

Description

This checker is deactivated in a default Polyspace^® as You Code analysis. See Checkers Deactivated in Polyspace as You Code Analysis (Polyspace Access).

Rule Definition

A project should not contain unused macro definitions.

Rationale

If a macro is defined but not used, a reviewer does not know if the macro is redundant or if it is unused by mistake.

Troubleshooting

If you expect a rule violation but do not see it, refer to Diagnose Why Coding Standard Violations Do Not Appear as Expected.

Examples

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Unused Macro Definition

void use_macro (void)
{
    #define SIZE 4
    #define DATA 3//Noncompliant

    use_int16(SIZE);
}

In this example, the macro DATA is never used in the use_macro function. Polyspace flags the unused macro.

Check Information

Group: Unused Code

Category: Advisory

AGC Category: Readability

Version History

Introduced in R2014b

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R2023b: Technical Corrigendum 2: Change in Title

The title of the rule is changed. The word 'declarations' is replaced by 'definitions'.

R2023b: Violations not reported on unused declarations in generated utility files

When generating code from a Simulink^® model, Embedded Coder^® generates utility files containing declarations for various utility functions. You can use these utility functions and macros in various other places in your project. Some of these utility functions can remain unused in your project. Starting in R2023b, Polyspace no longer reports violations of MISRA C™: 2012 rule 2.5 for the utility files.