RFC proposal for adding SORT_STRICT flag to array_unique()

Hello everybody! I'd like to open a discussion regarding the behavior of array_unique() with the SORT_REGULAR flag when used on arrays containing mixed types. Currently, SORT_REGULAR uses non-strict comparisons, which can lead to unintentional data loss when values like 100 and "100" are treated as duplicates. This forces developers to implement user-land workarounds. Here is a common scenario where this behavior is problematic: ```php $events = [ ['id' => 100, 'type' => 'user.login'], // User event (int) ['id' => "100", 'type' => 'system.migration'], // System event (string) ['id' => 100, 'type' => 'user.login'], // Duplicate user event ]; $event_ids = array_column($events, 'id'); // [100, "100", 100] // Current behavior with SORT_REGULAR $unique_ids = array_unique($event_ids, SORT_REGULAR); // Result: [100] // The string "100" is lost due to type coercion. ``` To address this, I propose adding a new flag, SORT_STRICT, which would use strict (===) comparisons to differentiate between values of different types. With the new flag, the result would be: ```php // Proposed behavior with SORT_STRICT $unique_ids = array_unique($event_ids, SORT_STRICT); // Result: [100, "100"] // Both integer and string values are preserved. ``` I've already submitted a PR to correct the bug I just highlighted: PR: https://github.com/php/php-src/pull/20273 The potential for a SORT_NATURAL flag also came to mind as another useful addition, but I believe SORT_STRICT is the more critical feature to discuss first. I look forward to your feedback. Thanks, - Jason