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Basic readonly property write checks

Group: Properties · Category: language · File: properties_readonly_assignment.php

References: - PHP readonly properties

Analyzer results

AnalyzerVersionResultDiagnostics
phan 6.0.11Phan 6.0.11 php-ast version 1.1.3 PHP version used to run Phan: 8.5.11 Pass 
properties_readonly_assignment.php:23: Saw attempt to modify class \Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox's property $value declared at /Users/megurine/repo/php/php-typing-conformance/conformance/tests/properties_readonly_assignment.php:17 (immutability of properties is enforced at runtime) [PhanTypeModifyImmutableObjectProperty]
phpstan 2.3.5PHPStan - PHP Static Analysis Tool 2.3.5 Pass reported Lv.2+ 
properties_readonly_assignment.php:23: Assign to protected(set) property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value. [reported-from-level=2]
With strict-rules
properties_readonly_assignment.php:23: Assign to protected(set) property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value.
psalm 6.20.9Psalm 6.20.9@f67170ac3c3b931f5088681e21d6c8babc601c08
next: 7.0.4		 Pass 
properties_readonly_assignment.php:23: Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value is marked readonly [InaccessibleProperty]
mago 1.59.0mago 1.59.0 Pass 
properties_readonly_assignment.php:23: Cannot initialize readonly property `Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value` from the global scope. [invalid-property-write]
mir 0.91.0mir 0.91.0 Pass 
properties_readonly_assignment.php:23: ReadonlyPropertyAssignment: Cannot assign to readonly property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value outside of constructor [MIR0600]
phpantom 0.11.1phpantom_lsp 0.11.1 Pass 
properties_readonly_assignment.php:23: Cannot modify readonly property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value from outside its declaring class [invalid_readonly_write]
intelephense 1.18.5intelephense 1.18.5 Pass 
properties_readonly_assignment.php:23: Cannot modify property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value from global scope. [P1056]
phpactor 2026.10.07.0Phpactor 2026.10.07.0 Fail

No diagnostics reported.

Expectation diff
Line 23: Expected 1 error(s)
phpy 1.0.19490phpy 1.0.19490 Pass 
properties_readonly_assignment.php:23: Cannot modify readonly property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value
qodana 262.11879.104PhpStorm 262.11879.104 Pass 
properties_readonly_assignment.php:23: Cannot write to 'readonly' property outside of declaration scope [PhpReadonlyPropertyWrittenOutsideDeclarationScopeInspection]
noverify 0.5.5NoVerify, version 0.5.5: built on: 2025.04.22 14:36:46 OS: r-kuchinskas arm64 Commit: 4774b82f8adc53fbef38f95e97af4b953b4d1529 Fail

No diagnostics reported.

Expectation diff
Line 23: Expected 1 error(s)
steins 0.1.8steins 0.1.8 (2026-09-21 revision 76306a9) Pass 
properties_readonly_assignment.php:23: Cannot modify readonly property ReadonlyBox::$value — proven Error [readonly.reassigned]
phpstan-strict 2.3.5PHPStan - PHP Static Analysis Tool 2.3.5 Pass 
properties_readonly_assignment.php:23: Assign to protected(set) property Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value.
psalm-next 7.0.4Psalm 7.0.4@fa5b1f6e665cb743838ffd865b8fc96207f9409f Pass 
properties_readonly_assignment.php:23: Conformance\Tests\PropertiesReadonlyAssignment\ReadonlyBox::$value is marked readonly [InaccessibleProperty]

Source

<?php

declare(strict_types=1);

namespace Conformance\Tests\PropertiesReadonlyAssignment;

/**
 * Basic readonly property write checks.
 *
 * References:
 * - PHP readonly properties
 */

final class ReadonlyBox
{
    public function __construct(
        public readonly int $value,
    ) {
    }
}

$box = new ReadonlyBox(1);
$box->value = 2; // E: readonly property cannot be reassigned