MISRA.IF.DEFINED

Incorrect 'defined' usage in #if directive.

MISRA-C Rule 19.14 (required): The defined preprocessor operator shall only be used in one of the two standard forms.

This rule is also covered by MISRA.ELIF.DEFINED.

[Undefined 47]

The only two permissible forms for the defined preprocessor operator are:

defined( identifier )

defined identifier

Any other form leads to undefined behaviour, for example:

#if defined(X > Y) /* not compliant - undefined behaviour */

Generation of the token defined during expansion of a #if or #elif preprocessing directive also leads to undefined behaviour and shall be avoided, for example:

#define DEFINED defined
#if DEFINED(X) /* not compliant - undefined behaviour */

MISRA-C++ Rule 16-1-1 (required): The defined preprocessor operator shall only be used in one of the two standard forms.

This rule is also covered by MISRA.ELIF.DEFINED.

[Undefined 16.1(4)]

Rationale

The only two permissible forms for the defined preprocessor operator are:

defined ( identifier )

defined identifier

Any other form is a constraint violation, but this is not reported by all compliers.

Example

#if defined ( X > Y ) // Non-compliant — constraint violation

Generation of the token defined during expansion of a '#if' or '#elif' preprocessing directive also leads to undefined behaviour and shall be avoided, for example:

#define DEFINED defined
#if DEFINED(X) // Non-compliant - undefined behaviour