psalm/docs/running_psalm/issues/UnsupportedPropertyReferenceUsage.md

UnsupportedPropertyReferenceUsage

Psalm cannot guarantee the soundness of code that uses references to properties.

Examples of Uncaught Errors

• Instance property assigned wrong type:

<?php
class A {
    public int $b = 0;
}
$a = new A();
$b = &$a->b;
$b = ''; // Fatal error

• Static property assigned wrong type:

<?php
class A {
    public static int $b = 0;
}
$b = &A::$b;
$b = ''; // Fatal error

• Readonly property reassigned:

<?php
class A {
    public function __construct(
        public readonly int $b,
    ) {
    }
}
$a = new A(0);
$b = &$a->b;
$b = 1; // Fatal error