ext/filter: `filter_var_array` with `FILTER_VALIDATE_INT|FILTER_NULL_ON_FAILURE` for an entry flag does not validate.

[Girgias]

Description

The following code:

<?php
$data = [
    'product_id' => '42',
    'component1'  => '10.36',
    'component2'  => '10.36',
];

$filters = [
    'product_id'   => FILTER_VALIDATE_INT,
    'component1'    => FILTER_VALIDATE_INT,
    'component2'    => FILTER_VALIDATE_INT|FILTER_NULL_ON_FAILURE,
    'doesnotexist1' => FILTER_VALIDATE_INT,
    'doesnotexist2' => FILTER_VALIDATE_INT|FILTER_NULL_ON_FAILURE,
];

var_dump(filter_var_array($data, $filters));

Resulted in this output:

array(5) {
  ["product_id"]=>
  int(42)
  ["component1"]=>
  bool(false)
  ["component2"]=>
  string(5) "10.36"
  ["doesnotexist1"]=>
  NULL
  ["doesnotexist2"]=>
  NULL
}

But I expected this output instead:

array(5) {
  ["product_id"]=>
  int(42)
  ["component1"]=>
  bool(false)
  ["component2"]=>
  NULL
  ["doesnotexist1"]=>
  NULL
  ["doesnotexist2"]=>
  NULL
}

PHP Version

PHP 5.4.0 to master

Operating System

No response

[nielsdos]

I investigated this.
Correct usage seems to be:

'component2'    => ['filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_NULL_ON_FAILURE],

and this works as expected.
I suppose we could at least do with a warning like filter_var emits when having an invalid filter ID, such that users know they're using it "wrong".

[Girgias]

Yeah, I think this makes sense as it is quite confusing of a behaviour