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IAR Embedded Workbench for Arm 9.70.x

CERT-EXP30-C_a

In this section:
Synopsis

Do not depend on the order of evaluation for side effects.

Enabled by default

Yes

Severity/Certainty

Medium/Medium

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Full description

Evaluation of an expression may produce side effects. At specific points during execution, known as sequence points, all side effects of previous evaluations are complete, and no side effects of subsequent evaluations have yet taken place. Do not depend on the order of evaluation for side effects unless there is an intervening sequence point. This check is identical to MISRAC++2008-5-0-1_a, MISRAC2004-12.2_a, MISRAC2012-Rule-1.3_i, MISRAC2012-Rule-13.2_a, SPC-order.

Coding standards
CERT EXP30-C

Do not depend on order of evaluation between sequence points

MISRA C:2004 12.2

(Required) The value of an expression shall be the same under any order of evaluation that the standard permits.

MISRA C:2012 Rule-1.3

(Required) There shall be no occurrence of undefined or critical unspecified behaviour

MISRA C:2012 Rule-13.2

(Required) The value of an expression and its persistent side effects shall be the same under all permitted evaluation orders

MISRA C++ 2008 5-0-1

(Required) The value of an expression shall be the same under any order of evaluation that the standard permits.

Code examples

The following code example fails the check and will give a warning:

void example(int i, int *b) {
    int a = i + b[++i];
}

The following code example passes the check and will not give a warning about this issue:

void example(int i, int *b) {
    {
        int a;
        ++i;
        a = i + b[i];
    }
    {
        int a = i + b[i + 1];
        ++i;
    }
}