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<?php spl_autoload_register(function($class) { if ($class === 'A') { class A { public function foo($x): B { return new B; } } } else if ($class === 'B') { class B extends A { public function foo($x): C { return new C; } } } else if ($class === 'C') { class C extends B { } } }); (new C)->foo('blah');
Output for 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 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
Output for 7.1.25 - 7.1.31, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33
Fatal error: Declaration of B::foo($x): C must be compatible with A::foo($x): B in /in/AhD6U on line 11
Process exited with code 255.
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164.87 ms | 1441 KiB | 4 Q