3v4l.org

run code in 300+ PHP versions simultaneously
<?php class Foo implements \JsonSerializable { public function jsonSerialize() { return new self; } }
Output for 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
Deprecated: Return type of Foo::jsonSerialize() should either be compatible with JsonSerializable::jsonSerialize(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /in/PQj2L on line 4
Output for 5.6.38, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30

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186.76 ms | 402 KiB | 240 Q