EXP31-J. Avoid side effects in assertions

The assert() method is a convenient mechanism for incorporating diagnostic tests in code. Expressions used with the standard assert method should not have side effects. Typically, the behavior of the assert method depends on the status of a runtime property. If defined, the assert method is defined to evaluate its expression argument and abort if the result of the expression is convertible to false. If undefined, assertis defined to be a no-op. Consequently, any side effects resulting from evaluation of the expression in the assertion are lost in non-debugging versions of the code.

Noncompliant Code Example

void process(int index) {
  assert(index++ > 0); /* side effect */
  /* ... */
}

Compliant Solution

Avoid the possibility of side effects in assertions.

void process(int index) {
  assert(index > 0); /* no side effect */
  ++index;
  /* ... */
}

Risk Assessment

Side effects in assertions can lead to unexpected and erroneous behavior.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Other Languages

This rule appears in the C++ and C Secure Coding Standard as EXP31-CPP. Avoid side effects in assertions and [EXP31-C. Avoid side effects in assertions EXP31-C. Avoid side effects in assertions.

References

[Putting Assertions in Your Code] "As a rule, the expressions contained in assertions should be free ofside effects"