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<?php class A implements \JsonSerializable { public $prop; public function jsonSerialize() { $obj = new stdClass; if ($this->prop) { $obj->prop = $this->prop; } return $obj; } } class B implements \JsonSerializable { public $a; public function jsonSerialize() { $obj = new stdClass; if ($this->a) { $obj->a = $this->a; } return $obj; } } $a = new A; $b = new B; $b->a = $a; var_dump(json_encode($b));
Output for 8.1.0 - 8.1.34, 8.2.0 - 8.2.30, 8.3.0 - 8.3.30, 8.4.1 - 8.4.18, 8.5.0 - 8.5.3
Deprecated: Return type of A::jsonSerialize() should either be compatible with JsonSerializable::jsonSerialize(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /in/0vT33 on line 7 Deprecated: Return type of B::jsonSerialize() should either be compatible with JsonSerializable::jsonSerialize(): mixed, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in /in/0vT33 on line 23 string(8) "{"a":{}}"
Output for 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
string(8) "{"a":{}}"

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