Option for array_column() to preserve keys.

Hello internals, The function array_column() would be much more useful if there was an option to preserve the original array keys. I can create an RFC, but I think it is better to first discuss the options. This is requested in different places on the web, e.g. https://stackoverflow.com/questions/27204590/php-array-column-how-to-keep-the-keys/39298759 A workaround is proposed here and elsewhere, using array_keys() and array_combine() to restore the keys. However, this workaround not only adds complexity, but it breaks down if some items don't have the value key. See https://3v4l.org/im2gZ. A more robust workaround would be array_map(), but this is more complex and probably slower than array_column(), for the given purpose. Some links for your convenience: The function was introduced in this RFC, https://wiki.php.net/rfc/array_column It is now documented here, https://www.php.net/manual/en/function.array-column.php Some ideas how this could be fixed: 1. Allow a magic value (e.g. TRUE) for the $index_key parameter, that would cause the assoc behavior. To fully avoid BC break, this must be a value that previously was completely forbidden. The value TRUE is currently only forbidden with strict_types=1. A value of e.g. new \stdClass is fully forbidden, but would be weird. A constant could be introduced, but this would not prevent the BC concern. 2. Make the function preserve keys if $index_key === NULL. This would be a full BC break. 3. Add an additional parameter with a boolean option or with integer flags. This would be weird, because it would make the $index_key parameter useless. 4. Add a new function. Personally I would prefer option 1, with value TRUE (I can't think of something better). If I could change history, I would prefer option 2. The current behavior could still be achieved with array_values(array_column(..)). Regards, Andreas