Why is this an issue?
Conditional expressions which are always true or false can lead to unreachable code.
Noncompliant code example
a = false;
if (a) { // Noncompliant
doSomething(); // never executed
}
if (!a || b) { // Noncompliant; "!a" is always "true", "b" is never evaluated
doSomething();
} else {
doSomethingElse(); // never executed
}
Resources
- MISRA C:2004, 13.7 - Boolean operations whose results are invariant shall not be permitted.
- MISRA C:2012, 14.3 - Controlling expressions shall not be invariant
- MITRE, CWE-570 - Expression is Always False
- MITRE, CWE-571 - Expression is Always True
- CERT, MSC12-C. - Detect and remove code that has no effect or is never executed
