Wanted to add this has been seen on Ubuntu and Mac.

We have temporarily worked around this by referencing `$this->app` within the Closure which is set to the same value that `$app` was previously.

So, Laravel >= 5.7.18 should not be affected by this; however, I am worried the bug could affect other areas of code we haven't discovered yet.

Off-topic comment by spam2 at rhsoft dot net deleted.

Might be duplicate / similar issue as: https://bugs.php.net/bug.php?id=77275

Can you please check with the fix for that bug[1] applied? Instead
of applying the fix yourself, you can also test with PHP
7.3.1RC1[2] (announcement including hashes and signatures will
follow shortly).

Anyhow, this issue might also be related to bug #76937.

[1] <http://git.php.net/?p=php-src.git;a=commit;h=93aabf1533bd3af673bb59cf283e6599ced3ab9a>
[2] <http://downloads.php.net/~cmb/>

I believe a problem I just ran across is related / same as this.  This is with PHP 7.3 nts x64 (I tried 7.3.1RC1 and same problem) on Windows 2016.

---[begin]
<?php
$data[0][0] = 'zero';
$data[0][1] = 0;
$data[1][0] = 'one';
$data[1][1] = 1;
$data[2][0] = 'two';
$data[2][1] = 2;

function breakit($op,$table,$data_arr,$qual="") {
	switch ($op) {
		case "go":
			$foo[0] = "";
			$foo[1] = "";
			$bar[0] = "";
			$bar[1] = "";
			for($i = 0; $i < count($data_arr); $i++)
			{
				if ($foo[0] != "") { $foo[0]=$foo[0].","; $foo[1]=$foo[1].","; }
				if ($bar[0] != "") { $bar[0]=$bar[0].","; $bar[1]=$bar[1].","; }
				
				$field = "`".$data_arr[$i][0]."`";
				$val = "'".$data_arr[$i][1]."'";

				$foo[0] .= $field;
				$foo[1] .= $val;
				$bar[0] = $bar[0].$field;
				$bar[1] = $bar[1].$val;
			}
			echo "foo[0]: ".$foo[0]."<br>";
			echo "foo[1]: ".$foo[1]."<br>";
			echo "bar[0]: ".$bar[0]."<br>";
			echo "bar[1]: ".$bar[1]."<br>";
			
			break;
	}
}

breakit('go','table',$data);
?>
---[end]

output--

foo[0]:
foo[1]:
bar[0]: `zero`,`one`,`two`
bar[1]: '0','1','2' (edited) 

... with opcache enabled the string concatenation of "var .= value" produces an empty string.  But using "var = var . value" works fine.  Disable opcache and output of foo and bar is identical.

I to have experienced this bug. Happens every time after first page load. Totally broke my games stat system. 

Code works ok on first attempt after ftp upload, get 0's every time afterwards.

OpCache for php 7.2.13 has no issue, only php 7.3 has the issue. Disabling opcache solves the problem. Using Ubuntu 18.

Test code:

class itest{
	
	function make_user_stats():array{
		
		$stats = array(
			'strength'  => 0,
			'stamina'   => 0,
			'intellect' => 0,
			'spirit'    => 0,
			'agility'   => 0,
			'armor'     => 0,
			'resist'    => 0
		);	
		
		$item_stats = array(
			'stam_x'     => 0,
			'str_x'      => 0,
			'int_x'      => 0,
			'agi_x'      => 0,
			'spirit_x'   => 0,
			'armor_inc'  => 0,
			'resist_inc' => 0
		);	
		
		$count = count($rows = array(
			array(
				'intellect' => 100,
				'stamina' => 200,
				'strength' => 30,
				'spirit' => 300,
				'agility' => 500,
				'resist' => 5,
				'armor' => 5,
			),
			array(
				'intellect' => 200,
				'stamina' => 300,
				'strength' => 330,
				'spirit' => 40,
				'agility' => 100,
				'resist' => 10,
				'armor' => 5,
			),
			array(
				'intellect' => 250,
				'stamina' => 120,
				'strength' => 330,
				'spirit' => 30,
				'agility' => 5,
				'resist' => 10,
				'armor' => 10,
			),				
		));
		
		foreach( $rows as $row ){
			
			$item_stats['stam_x']      += $row['stamina'];
			$item_stats['str_x']      += $row['strength'];
			$item_stats['int_x']      += $row['intellect'];
			$item_stats['agi_x']      += $row['agility'];
			$item_stats['spirit_x']   += $row['spirit'];
			$item_stats['armor_inc']  += $row['armor'];
			$item_stats['resist_inc'] += $row['resist'];
			
			//var_dump($item_stats);
			
		}
		
		$stats['stamina']   += ceil( ($stats['stamina']   * ($item_stats['stam_x']/100)) )   + $item_stats['stam_x'];
		$stats['intellect'] += ceil( ($stats['intellect'] * ($item_stats['int_x']/100)) )    + $item_stats['int_x'];
		$stats['strength']  += ceil( ($stats['strength']  * ($item_stats['str_x']/100)) )    + $item_stats['str_x'];
		$stats['agility']   += ceil( ($stats['agility']   * ($item_stats['agi_x']/100)) )    + $item_stats['agi_x'];
		$stats['spirit']    += ceil( ($stats['spirit']    * ($item_stats['spirit_x']/100)) ) + $item_stats['spirit_x'];	
		
		$stats['armor']    += $item_stats['armor_inc'];	
		$stats['resist']    += $item_stats['resist_inc'];		
		
		return $stats;
		
	}
	
}

$itest = new itest;

$stats = $itest->make_user_stats();

var_dump($stats);

@syntax53: That looks like bug #77257 to me, based on the involvement of switch. I can't reproduce this issue on current 7.3 tip.

@titansoftime: Can't reproduce that on on current 7.3 tip either, though not sure which bug would have fixed that one.

@syntax53 @titansoftime Ooops, nevermind what I just said, I tested the wrong PHP build. Both of your test cases still reproduce on current 7.3. I will take a look.

@syntax53 Your issue is fixed by https://github.com/php/php-src/commit/6f75890e7b8fee3584ec0fa7bd2017e8e75aea91.

@titansoftime And yours as well :) Turned out to be the same problem.

@nikic -- thanks!  How can we track to see when this has been included in an Release/Candidate?

> How can we track to see when this has been included in an
> Release/Candidate?

Ideally, you'd had filed a separate ticket – if it had been the
same root cause, that would have been closed as duplicate.
Otherwise it would have gotten its own NEWS/Changelog entry.

Anyhow, the fix should be in 7.3.2RC1, scheduled for Jan. 24th.

@cmb -- Sorry, as I was going to submit the ticket I saw all the warnings against submitting duplicates and this one had seemed very plausible that it could have been the same root cause.

I believe this has been fixed by one of the opcache fixes in an early 7.3 release, though I don't remember which one exactly it was. Please correct me if I'm wrong :)