SplPriorityQueue does not support serialization

[nikic]

Description

The following code:

<?php
$bar = new \SplPriorityQueue();
$bar->insert('a', 1);
var_dump($bar);
var_dump(unserialize(serialize($bar)));

Resulted in this output:

object(SplPriorityQueue)#1 (3) {
  ["flags":"SplPriorityQueue":private]=>
  int(1)
  ["isCorrupted":"SplPriorityQueue":private]=>
  bool(false)
  ["heap":"SplPriorityQueue":private]=>
  array(1) {
    [0]=>
    array(2) {
      ["data"]=>
      string(1) "a"
      ["priority"]=>
      int(1)
    }
  }
}
object(SplPriorityQueue)#2 (3) {
  ["flags":"SplPriorityQueue":private]=>
  int(1)
  ["isCorrupted":"SplPriorityQueue":private]=>
  bool(false)
  ["heap":"SplPriorityQueue":private]=>
  array(0) {
  }
}

But I expected this output instead:

object(SplPriorityQueue)#1 (3) {
  ["flags":"SplPriorityQueue":private]=>
  int(1)
  ["isCorrupted":"SplPriorityQueue":private]=>
  bool(false)
  ["heap":"SplPriorityQueue":private]=>
  array(1) {
    [0]=>
    array(2) {
      ["data"]=>
      string(1) "a"
      ["priority"]=>
      int(1)
    }
  }
}

object(SplPriorityQueue)#2 (3) {
  ["flags":"SplPriorityQueue":private]=>
  int(1)
  ["isCorrupted":"SplPriorityQueue":private]=>
  bool(false)
  ["heap":"SplPriorityQueue":private]=>
  array(1) {
    [0]=>
    array(2) {
      ["data"]=>
      string(1) "a"
      ["priority"]=>
      int(1)
    }
  }
}

Disclaimer: I don't have any need for this myself, just cross-posting an issue originally reported against apcu in krakjoe/apcu#505. It does seem weird that an SPL container cannot be serialized (or rather, loses data on serialization) though.

PHP Version

All

Operating System

No response

[MorganLOCode]

Ditto for Spl{Min,Max}Heap, and other concrete SplHeap classes (though SplPriorityQueue isn't explicitly such, it does use a max heap internally, presumably the same code).