LANG.STRUCT.CGEN.EMPE : Excessive Macro Parameter Evaluation in C Generic

JavaScript is not currently enabled, but is required for full CodeSonar manual search and browse functionality.

If you are viewing this file in your hub's Web GUI, enable JavaScript in your browser: you will also need it for GUI functionality.

If you opened this file directly from disk, your browser may be directly suppressing JavaScript functionality: certain browsers perform this suppression on local files (but not files delivered by web servers) for security reasons.

If you access the manual through the hub's Web GUI, the functionality will not be suppressed because the hub is a web server.
Alternatively, your browser may allow you to explicitly disable the security setting that suppresses functionality. See the CodeSonar FAQ for more information.

CodeSonar^® 9.2p0

CONFIDENTIAL

CodeSecure Inc

C and C++

LANG.STRUCT.CGEN.EMPE : Excessive Macro Parameter Evaluation in C Generic

Summary

A C generic selection expression for which both of the following are true.

The expression is inside a macro body.
An association in the expression's association list evaluates the same macro parameter two or more times.

Properties

Class Name

Excessive Macro Parameter Evaluation in C Generic

Significance

style

Mnemonic

LANG.STRUCT.CGEN.EMPE

Categories

MisraC2025	MisraC2025:23.7	A generic selection that is expanded from a macro should evaluate its argument only once
MisraC2023	MisraC2023:23.7	A generic selection that is expanded from a macro should evaluate its argument only once
Misra2012	Misra2012:23.7	A generic selection that is expanded from a macro should evaluate its argument only once

Availability

Available for C only (not C++).

Enabling

Checks for this warning class are disabled by default, and require the unnormalized C ASTs for the project. To enable them, add the following WARNING_FILTER rule and RETAIN_UNNORMALIZED_C_AST specification to the project configuration file.

RETAIN_UNNORMALIZED_C_AST = Yes
WARNING_FILTER += allow class="Excessive Macro Parameter Evaluation in C Generic"

Note that retaining the unnormalized ASTs will increase the disk space used to store the project representation, and may make the analysis take longer.

Example

/* 'Excessive Macro Parameter Evaluation in C Generic' warning issued on following line
 * ('Inconsistent Macro Parameter Evaluation in C Generic' warning also issued when enabled)
 */
#define EMPE_ONE(x) _Generic(x, \
                             int:x+x, /* two expansions of x */ \
                             default:x)

#define EMPE_OK1(x) _Generic(x, int:x, default:x)  /* ok: at most one expansion of x per association */
#define EMPE_OK2(x) _Generic(x, int:1, default:0)  /* ok: no expansions of x */
#define EMPE_OK3(x) _Generic(x, int:x, default:0)  /* ok: at most one expansion of x per association
                                                    * ('Inconsistent Macro Parameter Evaluation in C Generic'
                                                    *   warning issued when enabled)
                                                    */

Relevant Configuration File Parameters

The following configuration file parameters affect checks for this warning class.

To report problems with this documentation, please visit https://support.codesecure.com/.