[php-src] Issue #9885: [PHP 8.0.25] Function JIT may skip implicit type conversion in some cases, causing an error

Issue: https://github.com/php/php-src/issues/9885 Author: mszabo-wikia ### Description Hello, We observed that the following code throws a TypeError when function JIT is enabled: ```php <?php class ContentReviewLiveRevisionStorage implements LiveRevisionStorage { private const CURRENT_REVIEWED_REVISIONS_TABLE = 'current_reviewed_revisions'; private $lb; public function __construct( ILoadBalancer $lb ) { $this->lb = $lb; } public function getRevisionID( int $wikiId, int $pageId ): ?int { $dbr = $this->lb->getConnection( DB_REPLICA ); $revision = $dbr->selectField( self::CURRENT_REVIEWED_REVISIONS_TABLE, 'revision_id', [ 'wiki_id' => $wikiId, 'page_id' => $pageId, ] ); return $revision === false ? null : $revision; } } ``` selectField in this context ultimately ends up calling mysqli::query and mysqli::fetch_row, then returns the first element from the result row via reset().[1] Due to the data types in the table, $revision will then either be a numeric string, or false. Thus, it should be implicitly convertible to int if it is a numeric string, since strict types are not enabled here—but with function JIT, this method instead throws: ``` TypeError from line 28 of /extensions/fandom/FandomIncludes/src/ResourceLoader/Storage/ContentReviewLiveRevisionStorage.php: Fandom\Includes\ResourceLoader\Storage\ContentReviewLiveRevisionStorage::getRevisionID(): Return value must be of type ?int, string returned ``` This error does not occur with tracing JIT. I attempted to create a reproduction class that would do something similar (query a table via mysqli, fetch the first item of a result row using reset() and return $value === false ? null : $value from a method declared to return ?int), then invoked this in a loop. Unfortunately I was unable to reproduce the error with the synthetic attempt. I will update this issue if I do manage to somehow create a consistent reproducer. Thanks in advance! --- [1] https://github.com/wikimedia/mediawiki/blob/e9f9d892ab4cb5f8befc9e2b6753c97e26c2bb46/includes/libs/rdbms/database/Database.php#L1839 ### PHP Version PHP 8.0.25 ### Operating System _No response_