3v4l.org

run code in 300+ PHP versions simultaneously
<?php class A { public function run(): mixed { return null; } } class B extends A { public function run(): string { return 'test'; } } echo (new B())->run();
Output for 8.0.1 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
test
Output for 7.4.0 - 7.4.33
Fatal error: Declaration of B::run(): string must be compatible with A::run(): mixed in /in/NcBW6 on line 13
Process exited with code 255.

preferences:
141.35 ms | 401 KiB | 123 Q