utf8_encode() and utf8_decode() are deprecated in PHP 8.2, because their names are quite misleading (RFC): they convert strings from Latin 1 to UTF-8 and vice versa.
Wikibase uses them in SimpleCacheWithBagOStuff (since the original revision of that class):
private function serialize( $value ) { $serializedValue = serialize( $value ); $dataToStore = utf8_encode( $serializedValue ); $signature = hash_hmac( 'sha256', $dataToStore, $this->secret ); return json_encode( [ $signature, $dataToStore ] ); } private function unserialize( $string, $default, array $loggingContext ) { $result = json_decode( $string ); // ... $decodedData = utf8_decode( $data ); if ( $decodedData === serialize( false ) ) { return false; } // phpcs:disable Generic.PHP.NoSilencedErrors.Discouraged $value = @unserialize( $decodedData, [ 'allowed_classes' => [ \stdClass::class ] ] ); // ... return $value; }
I’m pretty sure this use of the functions is pointless (though “correct” in that the methods perform their inverse operations). MediaWiki sets mb_internal_encoding( 'UTF-8' ); early in Setup.php (since T137509), so there is no reason to assume that PHP serialize() returns Latin 1 that needs to be UTF-8 encoded before being passed into json_encode() – we’re just putting JSONified mojibake in the inner cache.
> $c = new HashBagOStuff() > ( new Wikibase\Lib\SimpleCacheWithBagOStuff( $c, 'prefix', 'secret' ) )->set( 'key', 'äöü' ) > $c->get( $c->makeKey( 'prefix', 'key' ) ) = "["9b94f92e4cfdcd3a282fc9398acd9a77f6d74d72fe95930c67e3edc44ece2745","s:6:\"\u00c3\u00a4\u00c3\u00b6\u00c3\u00bc\";"]" > json_decode( $c->get( $c->makeKey( 'prefix', 'key' ) ) )[1] = "s:6:"äöü";"
We should remove both method calls. (But we’ll need to tweak the cache key at the same time, to ensure that old mojibake serializations don’t get deserialized without the utf8_decode().)