Proposal: Dump circular references in var_export() using IIFE

[carlosmintfan]

When having $a = array(&$a) and calling var_export($a), instead of getting

PHP Warning:  var_export does not handle circular references in php shell code on line 1
array (
  0 => NULL,
)

we could make it return an IIFE like ((function(){$a = array(&$a);return $a;})()) so we can declare that circular reference using a variable without the risk to change variables in the code where the output of var_export() will be used.

[iluuu1994]

var_export() doesn't really support references to begin with. E.g:

$a = ['foo'];
$b = [&$a, &$a];
var_export($b);

Results in:

array (
  0 => 
  array (
    0 => 'foo',
  ),
  1 => 
  array (
    0 => 'foo',
  ),
)

Honestly, I'm not sure supporting recursive arrays is a worthwhile goal. Recursive arrays are a foot gun, because many things can trigger fatal errors. E.g.:

$a = [&$a];
var_dump($a === [[]]);

Can you clarify what your use-case is?

[carlosmintfan]

I don't really have a practical use case for it. This was just an idea how it could be implemented theoretically. :)

[iluuu1994]

@carlosmintfan Thank you for clarifying! In that case, I'd honestly prefer closing this as a #wontfix until we know why we're doing it. But I'll keep this open for a few days for others to chime in.

[carlosmintfan]

$a = [&$a];
var_dump($a === [[]]);

Oh wow, why doesn't this just eval to false?

[iluuu1994]

In this case, we probably could. But encountering recursive elements doesn't necessarily mean the elements are not equal. For example:

$a = [&$a];
$b = [[&$b]];
$a === $b;

These arrays should be equal, but understanding they are equal can get quite tricky. While we could probably find a solution for this but it might impact performance of comparison overall, which would not be a good trade-off IMO. I'm not exactly sure why we're not just throwing an Error, instead of a fatal error. I'll have a look at that.