property.readOnlyByPhpDocAssignOutOfClass

Code example

<?php declare(strict_types = 1);

class Foo
{
	/** @readonly */
	public int $value;

	public function __construct(int $value)
	{
		$this->value = $value;
	}
}

class Bar
{
	public function modify(Foo $foo): void
	{
		$foo->value = 42;
	}
}

Why is it reported?

The property is marked as @readonly in its PHPDoc, which means it should only be assigned inside the constructor of its declaring class. Code outside the declaring class is attempting to assign a value to this property, which violates the readonly contract.

The @readonly PHPDoc annotation is a PHPStan-enforced convention that mirrors the behavior of PHP's native readonly keyword but works on older PHP versions or in cases where the native keyword cannot be used.

How to fix it

Move the assignment into the declaring class's constructor or remove it:

 <?php declare(strict_types = 1);

 class Bar
 {
-	public function modify(Foo $foo): void
-	{
-		$foo->value = 42;
-	}
+	public function createFoo(): Foo
+	{
+		return new Foo(42);
+	}
 }

If the property genuinely needs to be writable from outside the class, remove the @readonly annotation:

 <?php declare(strict_types = 1);

 class Foo
 {
-	/** @readonly */
 	public int $value;

 	public function __construct(int $value)
 	{
 		$this->value = $value;
 	}
 }