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IAR Embedded Workbench for Arm 9.70.x

MISRAC++2008-5-0-1_a

In this section:
Synopsis

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

Enabled by default

Yes

Severity/Certainty

Medium/High

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Full description

There are expressions that depend on the order of evaluation. This check is identical to MISRAC2004-12.2_a, MISRAC2012-Rule-1.3_i, MISRAC2012-Rule-13.2_a, SPC-order, CERT-EXP30-C_a.

Coding standards
CERT EXP10-C

Do not depend on the order of evaluation of subexpressions or the order in which side effects take place

CERT EXP30-C

Do not depend on order of evaluation between sequence points

CWE 696

Incorrect Behavior Order

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

Code examples

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

int main(void) {
  int i = 0;
  i = i * i++;  //unspecified order of operations
  return 0;
}

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

int main(void) {
  int i = 0;
  int x = i;  
  i++;
  x = x * i;  //OK - statement is broken up  
  return 0;
}