LANG.STRUCT.SE.INC : Side Effects in Expression with Increment

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CodeSonar^® 9.2p0

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C and C++

LANG.STRUCT.SE.INC : Side Effects in Expression with Increment

Summary

An expression that contains a pre-increment or post-increment operation ++ has one or more other side-effects.

For the purposes of this check:

Function calls are always considered to contain side-effects unless one or more of the following is true:
- the function is declared with GNU __attribute__((const)) or __attribute__((pure)), or
- the function name matches a SIDE_EFFECT_FREE_FUNCTIONS rule.
All sub-expressions of the expression are checked, regardless of whether or not they will be evaluated.

Properties

Class Name

Side Effects in Expression with Increment

Significance

style

Mnemonic

LANG.STRUCT.SE.INC

Categories

MisraC2025	MisraC2025:13.3	A full expression containing an increment (++) or decrement (--) operator should have no other potential side effects other than that caused by the increment or decrement operator
MisraC2023	MisraC2023:13.3	A full expression containing an increment (++) or decrement (--) operator should have no other potential side effects other than that caused by the increment or decrement operator
Misra2012	Misra2012:13.3	A full expression containing an increment (++) or decrement (--) operator should have no other potential side effects other than that caused by the increment or decrement operator
Misra2004	Misra2004:12.13	The increment (++) and decrement (--) operators should not be mixed with other operators in an expression
AUTOSARC++14	AUTOSARC++14:M5-2-10	The increment (++) and decrement (--) operators shall not be mixed with other operators in an expression.
MisraC++2008	MisraC++2008:5-2-10	The increment ( ++ ) and decrement ( -- ) operators should not be mixed with other operators in an expression.
CERT-C	CERT-C:EXP30-C	Do not depend on the order of evaluation for side effects
	CERT-C:PRE31-C	Avoid side effects in arguments to unsafe macros
CERT-CPP	CERT-CPP:EXP50-CPP	Do not depend on the order of evaluation for side effects
JPL	JPL:19	Do not use expressions with side effects.

Availability

Available for C and 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="Side Effects in Expression with Increment"

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

int f(int);
int lang_struct_se_inc(int a){
    int i;
    i = a++;                    /* 'Side Effects in Expression with Increment' warning issued here */
    if (a){
        i++;                                                        /* no additional side effects */
    }
    a  = f(++i);                /* 'Side Effects in Expression with Increment' warning issued here */
    if (a + f(1)){              /* 'Side Effects in Expression with Increment' warning issued here
                                 *  - a function call is always considered to be a side effect */
        i = (1 == 1) ? 2 : a++; /* 'Side Effects in Expression with Increment' warning issued here
                                 * - even though the increment will not be executed
                                 * ('Unreachable Computation' warning also issued)
                                 */
    }
    return i + a;
}

Relevant Configuration File Parameters

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

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