3v4l.org

run code in 300+ PHP versions simultaneously
<?php class X {} class Y extends X {} class A { function f(Y &$y) {} } class B extends A { function f(X &$x) {} }
Output for 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Output for 7.0.0 - 7.0.20, 7.1.0 - 7.1.25, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33
Warning: Declaration of B::f(X &$x) should be compatible with A::f(Y &$y) in /in/e5DGI on line 11
Output for 5.5.24 - 5.5.35, 5.6.8 - 5.6.21
Strict Standards: Declaration of B::f() should be compatible with A::f(Y &$y) in /in/e5DGI on line 11
preferences:
167.72 ms | 402 KiB | 197 Q