3v4l.org

run code in 300+ PHP versions simultaneously
<?php class A { readonly string $x; public function initFromA() { $this->x = 'a'; } } class B extends A { readonly string $x; public function initFromB() { $this->x = 'b'; } } $c = new B; $c->initFromB(); var_dump($c->x); $c->initFromA(); // Error: alredy initialized
Output for 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
string(1) "b" Fatal error: Uncaught Error: Cannot modify readonly property B::$x in /in/9AV4r:6 Stack trace: #0 /in/9AV4r(20): A->initFromA() #1 {main} thrown in /in/9AV4r on line 6
Process exited with code 255.
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