logical vs assignment operator precedence in PHP

Question

Recently i came upon such snippet:

$x = 2 && $y = 3; echo (int)$x.\':\'.(int)$y;

Which produces output 1:3. By looking a

Answer 1

The operator precedence sheet you link to states as a separate note:

Although = has a lower precedence than most other operators, PHP will still allow expressions similar to the following: if (!$a = foo()), in which case the return value of foo() is put into $a.

So, in effect, an assignment inside an expression will be treated somewhat like a sub-expression. Exactly how and when this will happen isn't clear from the documentation, which just states that "similar" expressions will work this way.