new-static.php

<?php

class A {
  function create() {
		return new static();
	}
}

class B extends A {
}

class Caller {
	function call() {
		return B::create();
	}
}

$a = A::create();
$b1 = B::create();
$b2 = Caller::call();
$c = new Caller;
$b3 = $c->call();

var_dump(
	phpversion(),
	get_class($a),  # A
	get_class($b1), # B
	get_class($b2), # B
	get_class($b3)  # Caller    WTF!!!
);

/***

string(6) "5.3.21"
string(1) "A"
string(1) "B"
string(1) "B"
string(6) "Caller"

***/

I can confirm this behaviour.

My guess would be: In your example '$b3' is created with non static methods only. So there is no static context around for creation. When "new static()" is executed, PHP tries to "bubble" up the classes to find the last static scope to use that class name. But you do not have any static context at all, so PHP has to create one in the last class which is in your case "Caller". This might be abled to thread as a error. I would suggest a Bugreport....

Proof: With the callStatic() method, the correct B class is returned:

<?php
//...

class Caller {
  function call() {
    return B::create();
  }

  static function callStatic() {
    return B::create();
  }
}

$a = A::create();
$b1 = B::create();
$b2 = Caller::call();
$c = new Caller;
$b3 = $c->call();
$b4 = $c::callStatic();
$b5 = $c->callStatic();

var_dump(
  phpversion(),
  get_class($a),
  get_class($b1),
  get_class($b2),
  get_class($b3),
  get_class($b4),
  get_class($b5)
);

/***
string(16) "5.4.6-1ubuntu1.2"
string(1) "A"
string(1) "B"
string(1) "B"
string(6) "Caller"
string(1) "B"
string(1) "B"
***/