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Historical implicit-nullable parameter syntax

Group: Historical and legacy behavior · Category: historical · File: historical_implicit_nullable_parameter.php · Kind: Style / opinionated (no runtime-safety impact)

References: - python-typing historical group inspiration - legacy PHP signatures that relied on a null default before explicit nullable hints

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 
historical_implicit_nullable_parameter.php:14: Implicit nullable parameters (array $values = null) have been deprecated in PHP 8.4 [PhanDeprecatedImplicitNullableParam]
Expectation diff
Line 14: Unexpected errors ["Implicit nullable parameters (array $values = null) have been deprecated in PHP 8.4 [PhanDeprecatedImplicitNullableParam]"]
phpstan 2.2.8PHPStan - PHP Static Analysis Tool 2.2.8 Fail reported Lv.0+ 
historical_implicit_nullable_parameter.php:14: Deprecated in PHP 8.4: Parameter #1 $values (array) is implicitly nullable via default value null. [identifier=parameter.implicitlyNullable] [reported-from-level=0]
historical_implicit_nullable_parameter.php:14: Function Conformance\Tests\HistoricalImplicitNullableParameter\legacyImplicitNullable() has parameter $values with no value type specified in iterable type array. [identifier=missingType.iterableValue] [reported-from-level=6]
With strict-rules
historical_implicit_nullable_parameter.php:14: Deprecated in PHP 8.4: Parameter #1 $values (array) is implicitly nullable via default value null. [identifier=parameter.implicitlyNullable]
historical_implicit_nullable_parameter.php:14: Function Conformance\Tests\HistoricalImplicitNullableParameter\legacyImplicitNullable() has parameter $values with no value type specified in iterable type array. [identifier=missingType.iterableValue]
Expectation diff
Line 14: Unexpected errors ["Deprecated in PHP 8.4: Parameter #1 $values (array) is implicitly nullable via default value null. [identifier=parameter.implicitlyNullable] [reported-from-level=0]","Function Conformance\\Tests\\HistoricalImplicitNullableParameter\\legacyImplicitNullable() has parameter $values with no value type specified in iterable type array. [identifier=missingType.iterableValue] [reported-from-level=6]"]
psalm 6.16.1Psalm 6.16.1@f1f5de594dc76faf8784e02d3dc4716c91c6f6ac
next: 7.0.0-beta19		 Pass

No diagnostics reported.

mago 1.46.0mago 1.46.0 Pass

No diagnostics reported.

mir 0.70.1mir 0.70.1 Pass

No diagnostics reported.

phpantom 0.9.0phpantom_lsp 0.9.0 Pass

No diagnostics reported.

intelephense 1.18.5intelephense 1.18.5 Fail 
historical_implicit_nullable_parameter.php:14: Implicitly nullable parameters are deprecated. [P1078]
Expectation diff
Line 14: Unexpected errors ["Implicitly nullable parameters are deprecated. [P1078]"]
phpy 0.2.0phpy 0.2.0 Fail 
historical_implicit_nullable_parameter.php:14: Implicitly marking parameter $values as nullable is deprecated, the explicit nullable type must be used instead
Expectation diff
Line 14: Unexpected errors ["Implicitly marking parameter $values as nullable is deprecated, the explicit nullable type must be used instead"]
qodana 262.8665.325Qodana 262.8665.325 Fail 
historical_implicit_nullable_parameter.php:14: Implicitly marking parameter as nullable is deprecated [PhpDeprecatedImplicitlyNullableParameterInspection]
Expectation diff
Line 14: Unexpected errors ["Implicitly marking parameter as nullable is deprecated [PhpDeprecatedImplicitlyNullableParameterInspection]"]
noverify 0.5.5NoVerify, version 0.5.5: built on: 2025.04.22 14:36:46 OS: r-kuchinskas arm64 Commit: 4774b82f8adc53fbef38f95e97af4b953b4d1529 Fail 
historical_implicit_nullable_parameter.php:14: parameter with null default value should be explicitly nullable [notExplicitNullableParam]
Expectation diff
Line 14: Unexpected errors ["parameter with null default value should be explicitly nullable [notExplicitNullableParam]"]
steins 0.1.5steins 0.1.5 (2026-08-12 revision 39b4cc1) Fail 
historical_implicit_nullable_parameter.php:14: parameter $values of legacyImplicitNullable() is an iterable with no value type — write `array<T>`, `T[]`, `list<T>` or an array shape [untyped.iterable-value]
Expectation diff
Line 14: Unexpected errors ["parameter $values of legacyImplicitNullable() is an iterable with no value type — write `array<T>`, `T[]`, `list<T>` or an array shape [untyped.iterable-value]"]
phpstan-strict 2.2.8PHPStan - PHP Static Analysis Tool 2.2.8 Fail 
historical_implicit_nullable_parameter.php:14: Deprecated in PHP 8.4: Parameter #1 $values (array) is implicitly nullable via default value null. [identifier=parameter.implicitlyNullable]
historical_implicit_nullable_parameter.php:14: Function Conformance\Tests\HistoricalImplicitNullableParameter\legacyImplicitNullable() has parameter $values with no value type specified in iterable type array. [identifier=missingType.iterableValue]
Expectation diff
Line 14: Unexpected errors ["Deprecated in PHP 8.4: Parameter #1 $values (array) is implicitly nullable via default value null. [identifier=parameter.implicitlyNullable]","Function Conformance\\Tests\\HistoricalImplicitNullableParameter\\legacyImplicitNullable() has parameter $values with no value type specified in iterable type array. [identifier=missingType.iterableValue]"]
psalm-next 7.0.0-beta19Psalm 7.0.0-beta19@7e751c06a756fa64dc4c759c09fe4a173afcb433 Pass

No diagnostics reported.

Source

<?php

declare(strict_types=1);

namespace Conformance\Tests\HistoricalImplicitNullableParameter;

/**
 * Historical implicit-nullable parameter syntax.
 *
 * References:
 * - python-typing historical group inspiration
 * - legacy PHP signatures that relied on a null default before explicit nullable hints
 *
 * @conformance-kind style
 */
function legacyImplicitNullable(array $values = null): void // E?: implicit nullable parameter
{
}

legacyImplicitNullable();
legacyImplicitNullable([1, 2, 3]);