closure.useThis - Phpstan

Code example

php

<?php declare(strict_types = 1);

class Foo
{
	public function doFoo(): void
	{
		$fn = static function () use ($this) {
			echo $this->bar();
		};
	}

	public function bar(): string
	{
		return 'bar';
	}
}

Why is it reported?

The $this variable cannot be used as a lexical variable in a closure's use clause. PHP does not allow use ($this) -- it is a syntax error. Non-static closures already have access to $this automatically, so importing it is both unnecessary and invalid.

How to fix it

Remove $this from the use clause and make the closure non-static so it has access to $this:

diff-php

 <?php declare(strict_types = 1);

 class Foo
 {
 	public function doFoo(): void
 	{
-		$fn = static function () use ($this) {
-			echo $this->bar();
+		$fn = function () {
+			echo $this->bar();
 		};
 	}

 	public function bar(): string
 	{
 		return 'bar';
 	}
 }