ThisFoundOutsideClass fires false-positive on anonymous class

[totten]

Bug Description

The sniff ThisFoundOutsideClass fires a false-positive on $this when nested inside an anonymous class and a closure.

Given the following reproduction scenario

The issue happens when running this command:

./vendor/bin/phpcs -ps example.php --standard=PHPCompatibility --runtime-set testVersion 7.4-8.1

... over a file containing this code:

<?php

return function () {

  $obj = new class() {
    protected $x = 0;
    
    public function increment(): int {
      return ++$this->x;
    }
  };

};

with the built-in ruleset.

I'd expect the following behaviour

Pass

Instead this happened

FILE: /tmp/PHPCompatibility/example.php
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 9 | WARNING | Closures / anonymous functions only have access to $this if used within a class or when bound to an object using bindTo(). Please verify.
   |         | (PHPCompatibility.FunctionDeclarations.NewClosure.ThisFoundOutsideClass)
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Environment

Environment	Answer
PHP version	8.1.6; 7.4.29
PHP_CodeSniffer version	3.7.2
PHPCompatibility version	develop (circa 4576a17)
Install type	composer

Additional Context (optional)

This issue was pointed out to me as totten/civix#294. I can see it happening, so I'm forwarding it along with a tighter description.

Tested Against develop branch?

• I have verified the issue still exists in the develop branch of PHPCompatibility.

[jrfnl]

@totten Thanks for reporting this. I have confirmed the issue and lined up a fix, which will be pulled & merged before the 10.0.0 release.

[jrfnl]

FYI: it's not even just anonymous classes... looks like named classes and other closed structures can all be declared within a closure: https://3v4l.org/Zb22K

[totten]

FYI: it's not even just anonymous classes... looks like named classes and other closed structures can all be declared within a closure: https://3v4l.org/Zb22K

Ah, cool. Learn something new every day. 😄