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<?php class A {} class B {} class C { public function __construct( protected readonly A|B $b ) { if ($this->b instanceof A) { trigger_error('A is deprecated, pass B instead', E_USER_DEPRECATED); $this->b = new B(); } var_dump($this->b); } } new C(new A()); new C(new B());
Output for 8.1.0 - 8.1.31, 8.2.0 - 8.2.26, 8.3.5 - 8.3.15, 8.4.1 - 8.4.2
Deprecated: A is deprecated, pass B instead in /in/X6PNN on line 11 Fatal error: Uncaught Error: Cannot modify readonly property C::$b in /in/X6PNN:12 Stack trace: #0 /in/X6PNN(18): C->__construct(Object(A)) #1 {main} thrown in /in/X6PNN on line 12
Process exited with code 255.
Output for 8.0.1 - 8.0.30
Parse error: syntax error, unexpected identifier "A", expecting variable in /in/X6PNN on line 8
Process exited with code 255.

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