MISRA C:2023 Rule 20.13

Rule Definition

A line whose first token is # shall be a valid preprocessing directive

Rationale

You typically use a preprocessing directive to conditionally exclude source code until a corresponding #else, #elif, or #endif directive is encountered. If your compiler does not detect a preprocessing directive because it is malformed or invalid, you can end up excluding more code than you intended.

If all preprocessing directives are syntactically valid, even in excluded code, this unintended code exclusion cannot happen.

Troubleshooting

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