static_confusion.php

<?php
/**
 * @link https://l-x.github.io/blog/2014/09/29/messing-around-with-phps-late-static-binding/
 */

class A {

	public function createInstance() {
		/** 
		 * Calling method static even if 
		 * defined non-static in class B
		 */
		return B::createInstance();
	}
}

class B {

	public function createInstance() {
		return new static();
	}

}


$instance_of_A = new A();

$expected_instance_of_B = $instance_of_A->createInstance();

var_dump($expected_instance_of_B);

/**
 * Expected:
 * 
 * class B#2 (0) {
 * 
 * }
 * 
 * Result:
 * 
 * class A#2 (0) {
 * 
 * }
 * 
 */

This problem (feature?) already exists for a while: https://bugs.php.net/bug.php?id=50031