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.

Noncompliant Code Example

$a = 0;
$b = false;

$c = !!$a; // Noncompliant
$d = ~~$b; // Noncompliant

Compliant Solution

$a = 0;
$b = false;

$c = !$a; // Compliant
$d = ~$b; // Compliant