The repetition of a prefix operator (!, or ~) is usually a typo. The second operator invalidates the first one:
$a = false;
$b = ~~$a; // Noncompliant: equivalent to "$a"
While calling ! twice is equivalent to calling the boolval() function, the latter increases the code readability, so it
should be preferred.
$a = 0;
$b = !!$a; // Noncompliant: equivalent to "boolval($a)"
