L3989 False Positive in LoopsShouldNotBeInfiniteCheck: should support guard clause

[Donald_Frederick]

• SonarQube Enterprise Edition Version 8.9 (build 43852)
• error message: “‘parent’ is not modified in this loop.”

var parent = $container.find('.list')[0];
while (parent && parent.firstChild) {
  parent.removeChild(parent.firstChild);
}

I’m not sure where this is going wrong, I think it doesn’t understand this is a guard clause checking parent for a null-ish value to prevent “Cannot read property ‘firstChild’ of undefined” exception if .find() return no elements.

[Yassin (Yassin Kammoun)]

Hello Donald,

Welcome to SonarSource community, and thank you for your feedback.

The false positive you are mentioning is not due to a missing support of guard class but because of a current limitation of the rule. In your case, the loop condition partially depends on a mutable object, parent, which is modified through calls to removeChild. However, the rule doesn’t consider mutation of loop condition variables through function or method calls, and therefore, raises a false positive.

I created the following ticket to address this false positive.

Best,
Yassin