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<?php interface ITest { public function apfel(): mixed; } class Test implements ITest { public function apfel(): array { return []; } } var_dump((new Test())->apfel());
Output for 8.0.0 - 8.0.13, 8.1rc1 - rc3
array(0) { }
Output for 7.4.0 - 7.4.26
Fatal error: Declaration of Test::apfel(): array must be compatible with ITest::apfel(): mixed in /in/PXDB6 on line 10
Process exited with code 255.
Output for 7.3.0 - 7.3.33
Fatal error: Declaration of Test::apfel(): array must be compatible with ITest::apfel(): mixed in /in/PXDB6 on line 8
Process exited with code 255.

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