Code Inspection: Closure can be converted to arrow function

Reports the anonymous functions that can be transformed to short arrow functions. Support for short arrow functions is available since PHP 7.4.

See PHP RFC: Arrow Functions 2.0 (php.net) for details.

In the following example, the callback anonymous function inside array_map() is written in two forms: regular and arrow.

$myArr = [1, 2, 3, 4, 5, 6];
$doubledValues = array_map(function ($var) {
    return $var * 2;
}, $myArr);

$myArr = [1, 2, 3, 4, 5, 6];
$doubledValues = array_map(fn ($var) => $var * 2, $myArr);