code-completion.php

<?php

class Foo
{
  /**
   * @return self
   */
  public function foo()
  {
    return $this;
  }
  
  /**
   * @return $this
   */
  public function fooThis()
  {
    return $this;
  }
}

class Bar extends Foo
{
  public function bar()
  {
    echo "Yes!";
  }
}

// PhpStorm does not offer bar() as method here due to @return self
(new Bar())->foo()->bar();

// PhpStorm correctly handles code completion
(new Bar())->fooThis()->bar();