Online PHP editor | refs for WV4jo

<?php declare(strict_types=1); class A { } class B extends A { } class C extends B { } class TestA { public function x(C $c):A { return new C(); } } class TestB extends TestA { public function x(B $b):B { return new C(); } } class TestC extends TestB { public function x(A $a): C { return new C(); } } $c = new C(); $testA = new TestA(); $testC = new TestC(); $resultA = $testA->x($c); $resultC = $testC->x($c); var_dump([ 'TestA::x(C): expect C' => get_class($resultA), 'TestC::x(C): expect C' => get_class($resultC), ]); $a = new A(); try { $resultA = $testA->x($a); echo "impossible"; } catch (TypeError $e){ echo "TestA::x(A): expected TypeError\n"; } echo 'TestC::x(A): expect C => '. get_class($testC->x($a));