LANG.STRUCT.LOOP.MFSTEP : Malformed for-loop Step

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The third ("step") clause of a for loop header has one or more of the following properties.

It includes one or more elements that are modified in the loop body.

It has one or more persistent side effects besides modifying the loop counter.

Class Name

Malformed for-loop Step

Significance

style

Mnemonic

LANG.STRUCT.LOOP.MFSTEP

Categories

MisraC2023	MisraC2023:14.2	A for loop shall be well-formed
Misra2012	Misra2012:14.2	A for loop shall be well-formed
AUTOSARC++14	AUTOSARC++14:A6-5-4	For-init-statement and expression should not perform actions other than loop-counter initialization and modification.
	AUTOSARC++14:M6-5-4	The loop-counter shall be modified by one of: --, ++, - = n, or + = n; where n remains constant for the duration of the loop.
	AUTOSARC++14:M6-5-5	A loop-control-variable other than the loop-counter shall not be modified within condition or expression.
MisraC++2008	MisraC++2008:6-5-4	The loop-counter shall be modified by one of -- , ++ , -=n , or +=n; where n remains constant for the duration of the loop.
	MisraC++2008:6-5-5	A loop-control-variable other than the loop-counter shall not be modified within condition or expression.
MisraC++2023	MisraC++2023:9.5.1	Legacy for statements should be simple
JSF++	JSF++:199	The increment expression in a for loop will perform no action other than to change a single loop parameter to the next value for the loop.

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="Malformed for-loop Step"

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

void lang_struct_loop_mfstep(void){
    int i=1;
    int k;
    int buf[10];


    for (k = 0; k < 10; k +=i){                /* k incremented, no other side effects */
      buf[i] = k; 
    }

    i = 0;
    for (k = 0; k < 10; k += i){ /* 'Malformed for-loop Step' warning issued here
                                  * - i modifed in loop body */
        buf[i++] = k; 
    }

    for (k = 0; k < 10; k = i++){/* 'Malformed for-loop Step' warning issued here
                                  * - side effect on i */
        /* ... */
    }

    for (k = 0; k < 10; i++){    /* 'Malformed for-loop Step' warning issued here
                                  * - side effect on i */
      /* ... */
    }

}

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

LANG.STRUCT.LOOP.MFSTEP : Malformed for-loop Step

Summary

Properties

Example

Relevant Configuration File Parameters