Calling the ! or ~ prefix operator twice does nothing: the second invocation undoes the first. Such mistakes are
typically caused by accidentally double-tapping the key in question without noticing. Either this is a bug, if the operator was actually meant to be
called once, or misleading if done on purpose.
$a = 0; $b = false; $c = !!$a; // Noncompliant $d = ~~$b; // Noncompliant
$a = 0; $b = false; $c = !$a; // Compliant $d = ~$b; // Compliant