Why PHP sucks, try to run this!

NastyBugTest.php

<?php

use PHPUnit\Framework\TestCase;

class NastyBugTest extends TestCase
{
    public function testBug()
    {   
        $data = [ 
            'c' => [
                [
                    'q' => 1,
                ],
                [
                    'q' => 2,
                ],
                [
                    'q' => 3,
                ],
            ]
        ];

        $before = $data;
        foreach ($data['c'] as &$c) {
        }

        $after = $data;
        $this->assertSame($before, $after);

        foreach ($data['c'] as $c) {
        }
        $after = $data;

        $this->assertSame($before, $after);
    }
    
    public function testFix()
    {   
        $data = [ 
            'c' => [
                [
                    'q' => 1,
                ],
                [
                    'q' => 2,
                ],
                [
                    'q' => 3,
                ],
            ]
        ];

        $before = $data;
        foreach ($data['c'] as &$c1) {
        }

        $after = $data;
        $this->assertSame($before, $after);

        foreach ($data['c'] as $c2) {
        }
        $after = $data;

        $this->assertSame($before, $after);
    }
}