[Request][Discussion] Double value as array key improvement

Hello everyone! I was working on following request https://bugs.php.net/bug.php?id=75053 <https://bugs.php.net/bug.php?id=75053> which resulted in following pull request https://github.com/php/php-src/pull/2676 <https://github.com/php/php-src/pull/2676> The problem here is following: when we’re using large numbers as array index when adding new elements it could overwrite already existing value. Assume we have 2 indexes 5076964154930102272 and 999999999999999999999999999999 with different value set for them. Because 999999999999999999999999999999 is larger than maximum long int number for 64-bit systems, it will be converted to double. (corresponding code here https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L1648 <https://github.com/php/php-src/blob/master/Zend/zend_language_scanner.l#L1648>) But when double value is used as array indexes, it is converted to long integer. (f.e., code is here https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L1573 <https://github.com/php/php-src/blob/master/Zend/zend_execute.c#L1573>) At this case it causes overflow and we’ve got index equal to 5076964154930102272 and as a result - we’re overwriting previously set value. My suggestion is following: 1) when double key is less than maximum possible long integer - convert it to integer 2) if it’s larger - convert it to string. That’s what implemented in proposed PR. Another possible option is just to throw warning in this case (proposed by Nikita Popov) I would happy to hear any feedback and suggestions about this solution. Thanks!