3v4l.org

run code in 300+ PHP versions simultaneously
<?php abstract class A { abstract public function foo(A $a): A; } class B extends A { public function foo(A $b): B { } }
Output for 7.4.3 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.6, 7.2.29 - 7.2.33, 7.3.16 - 7.3.33
Fatal error: Declaration of B::foo(A $b): B must be compatible with A::foo(A $a): A in /in/3NoOa on line 11
Process exited with code 255.

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