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Typed property reads before initialization

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

A typed property with no constructor assignment is uninitialized until written. Reading it is a runtime TypeError. Tools that only flag a missing constructor still count: they saw the unguarded property. References: - PHP typed properties - python-typing attribute initialization inspiration

Analyzer results

AnalyzerVersionResultDiagnostics
phan 6.0.7Phan 6.0.7 php-ast version 1.1.3 PHP version used to run Phan: 8.5.9 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
phpstan 2.2.11PHPStan - PHP Static Analysis Tool 2.2.11 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
psalm 6.16.1Psalm 6.16.1@f1f5de594dc76faf8784e02d3dc4716c91c6f6ac
next: 7.0.0-beta19		 Pass 
properties_uninitialized_read.php:21: Conformance\Tests\PropertiesUninitializedRead\User has an uninitialized property Conformance\Tests\PropertiesUninitializedRead\User::$name, but no constructor [MissingConstructor]
mago 1.47.4mago 1.47.4 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
mir 0.72.1mir 0.72.1 Pass 
properties_uninitialized_read.php:19: MissingConstructor: Class Conformance\Tests\PropertiesUninitializedRead\User has uninitialized properties but no constructor [MIR1507]
phpantom 0.10.0phpantom_lsp 0.10.0 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
intelephense 1.18.5intelephense 1.18.5 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
phpactor 2026.07.22.0Phpactor 2026.07.22.0 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
phpy 0.2.0phpy 0.2.0 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
qodana 262.9437.196Qodana 262.9437.196 Pass 
properties_uninitialized_read.php:25: Typed property 'name' might be uninitialized [PhpTypedPropertyMightBeUninitializedInspection]
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
Lines 19, 21, 25: Expected error (tag uninit)
steins 0.1.6steins 0.1.6 (2026-08-25 revision c13b4c7) Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
phpstan-strict 2.2.11PHPStan - PHP Static Analysis Tool 2.2.11 Fail

No diagnostics reported.

Expectation diff
Lines 19, 21, 25: Expected error (tag uninit)
psalm-next 7.0.0-beta19Psalm 7.0.0-beta19@7e751c06a756fa64dc4c759c09fe4a173afcb433 Pass 
properties_uninitialized_read.php:21: Conformance\Tests\PropertiesUninitializedRead\User has an uninitialized property Conformance\Tests\PropertiesUninitializedRead\User::$name, but no constructor [MissingConstructor]

Source

<?php

declare(strict_types=1);

namespace Conformance\Tests\PropertiesUninitializedRead;

/**
 * Typed property reads before initialization.
 *
 * A typed property with no constructor assignment is uninitialized until
 * written. Reading it is a runtime TypeError. Tools that only flag a
 * missing constructor still count: they saw the unguarded property.
 *
 * References:
 * - PHP typed properties
 * - python-typing attribute initialization inspiration
 */

final class User // E[uninit]
{
    public string $name; // E[uninit]: typed property without guaranteed initialization // E<psalm>: MissingConstructor on the declaration, not the read // E<pzoom>: same MissingConstructor as Psalm
}

$user = new User();
echo $user->name; // E[uninit]: read of a possibly uninitialized typed property