Bug #71238 [Com]: usort pass by reference inconsistency

Edit report at https://bugs.php.net/bug.php?id=71238&edit=1

 ID:                 71238
 Comment by:         [email protected]
 Reported by:        eugen dot alter at gmail dot com
 Summary:            usort pass by reference inconsistency
 Status:             Open
 Type:               Bug
 Package:            Arrays related
 Operating System:   any
 PHP Version:        7.0.1
 Block user comment: N
 Private report:     N

 New Comment:

Using var_export in PHP 5.5:

array (
  0 => 
  array (
    'name' => 'Bar',
    'children' => 
    array (
      0 => 
      array (
        'name' => 'X',
        'children' => 
        array (
        ),
      ),
      1 => 
      array (
        'name' => 'Y',
        'children' => 
        array (
        ),
      ),
      2 => 
      array (
        'name' => 'Z',
        'children' => 
        array (
        ),
      ),
    ),
  ),
  1 => 
  array (
    'name' => 'Foo',
    'children' => 
    array (
      0 => 
      array (
        'name' => 'A',
        'children' => 
        array (
        ),
      ),
      1 => 
      array (
        'name' => 'B',
        'children' => 
        array (
        ),
      ),
    ),
  ),
)

Using var_export in a slightly outdated master branch:

array (
  0 => 
  array (
    'name' => 'Bar',
    'children' => 
    array (
      0 => 
      array (
        'name' => 'Z',
        'children' => 
        array (
        ),
      ),
      1 => 
      array (
        'name' => 'X',
        'children' => 
        array (
        ),
      ),
      2 => 
      array (
        'name' => 'Y',
        'children' => 
        array (
        ),
      ),
    ),
  ),
  1 => 
  array (
    'name' => 'Foo',
    'children' => 
    array (
      0 => 
      array (
        'name' => 'B',
        'children' => 
        array (
        ),
      ),
      1 => 
      array (
        'name' => 'A',
        'children' => 
        array (
        ),
      ),
    ),
  ),
)


Previous Comments:
------------------------------------------------------------------------
[2015-12-29 16:38:59] eugen dot alter at gmail dot com

Description:
------------
In PHP 5.4 ... 5.6 passing compared array elements by reference and then changing them from inside comparison function works properly whilst in PHP7 it does not.

In sample script: function tries to sort arrays by key "name" on all nested levels. The nested levels are sorted correctly on PHP 5.4 .. 5.6 but not on PHP7.

Test script:
---------------
$array = [
    [
        'name'     => 'Foo',
        'children' => [
            [
                'name'     => 'B',
                'children' => []
            ],
            [
                'name'     => 'A',
                'children' => []
            ]
        ]
    ],
    [
        'name'     => 'Bar',
        'children' => [
            [
                'name'     => 'Z',
                'children' => []
            ],
            [
                'name'     => 'X',
                'children' => []
            ],
            [
                'name'     => 'Y',
                'children' => []
            ]
        ]
    ]
];

usort($array, $f = function(&$x, &$y) use (&$f){
    usort($x['children'], $f);
    usort($y['children'], $f);
    return strcasecmp($x['name'], $y['name']);
});

Expected result:
----------------
array(2) { [0]=> array(2) { ["name"]=> string(3) "Bar" ["children"]=> array(3) { [0]=> array(2) { ["name"]=> string(1) "X" ["children"]=> array(0) { } } [1]=> array(2) { ["name"]=> string(1) "Y" ["children"]=> array(0) { } } [2]=> array(2) { ["name"]=> string(1) "Z" ["children"]=> array(0) { } } } } [1]=> array(2) { ["name"]=> string(3) "Foo" ["children"]=> array(2) { [0]=> array(2) { ["name"]=> string(1) "A" ["children"]=> array(0) { } } [1]=> array(2) { ["name"]=> string(1) "B" ["children"]=> array(0) { } } } } }

Actual result:
--------------
array(2) { [0]=> array(2) { ["name"]=> string(3) "Bar" ["children"]=> array(3) { [0]=> array(2) { ["name"]=> string(1) "Z" ["children"]=> array(0) { } } [1]=> array(2) { ["name"]=> string(1) "X" ["children"]=> array(0) { } } [2]=> array(2) { ["name"]=> string(1) "Y" ["children"]=> array(0) { } } } } [1]=> array(2) { ["name"]=> string(3) "Foo" ["children"]=> array(2) { [0]=> array(2) { ["name"]=> string(1) "B" ["children"]=> array(0) { } } [1]=> array(2) { ["name"]=> string(1) "A" ["children"]=> array(0) { } } } } } 


------------------------------------------------------------------------



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Edit this bug report at https://bugs.php.net/bug.php?id=71238&edit=1