Fix array_column() with null as $column_key

Fixes phpstan/phpstan#6497

Author: jlherren

src/Type/Php/ArrayColumnFunctionReturnTypeExtension.php

@@ -16,6 +16,7 @@
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NeverType;
+use PHPStan\Type\NullType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypeUtils;
@@ -132,8 +133,17 @@ private function handleConstantArray(ConstantArrayType $arrayType, Type $columnT
 
 	private function getOffsetOrProperty(Type $type, Type $offsetOrProperty, Scope $scope, bool $allowMaybe): ?Type
 	{
+		$offsetIsNull = (new NullType())->isSuperTypeOf($offsetOrProperty);
+		if ($offsetIsNull->yes()) {
+			return $type;
+		}
+
 		$returnTypes = [];
 
+		if ($offsetIsNull->maybe()) {
+			$returnTypes[] = $type;
+		}
+
 		if (!$type->canAccessProperties()->no()) {
 			$propertyTypes = TypeUtils::getConstantStrings($offsetOrProperty);
 			if ($propertyTypes === []) {

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -651,6 +651,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4357.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5817.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/array-column.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-6497.php');
 
 		if (PHP_VERSION_ID >= 70400) {
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/isset-coalesce-empty-type.php');

tests/PHPStan/Analyser/data/array-column.php

@@ -10,6 +10,7 @@ function testArrays(array $array): void
 	/** @var array<int, array<string, string>> $array */
 	assertType('array<int, string>', array_column($array, 'column'));
 	assertType('array<int|string, string>', array_column($array, 'column', 'key'));
+	assertType('array<int|string, array<string, string>>', array_column($array, null, 'key'));
 
 	/** @var non-empty-array<int, array<string, string>> $array */
 	// Note: Array may still be empty!
@@ -18,13 +19,15 @@ function testArrays(array $array): void
 	/** @var array{} $array */
 	assertType('array{}', array_column($array, 'column'));
 	assertType('array{}', array_column($array, 'column', 'key'));
+	assertType('array{}', array_column($array, null, 'key'));
 }
 
 function testConstantArrays(array $array): void
 {
 	/** @var array<int, array{column: string, key: string}> $array */
 	assertType('array<int, string>', array_column($array, 'column'));
 	assertType('array<string, string>', array_column($array, 'column', 'key'));
+	assertType('array<string, array{column: string, key: string}>', array_column($array, null, 'key'));
 
 	/** @var array<int, array{column: string, key: string}> $array */
 	assertType('array{}', array_column($array, 'foo'));
@@ -33,20 +36,24 @@ function testConstantArrays(array $array): void
 	/** @var array{array{column: string, key: 'bar'}} $array */
 	assertType("array{string}", array_column($array, 'column'));
 	assertType("array{bar: string}", array_column($array, 'column', 'key'));
+	assertType("array{bar: array{column: string, key: 'bar'}}", array_column($array, null, 'key'));
 
 	/** @var array{array{column: string, key: string}} $array */
 	assertType("non-empty-array<string, string>", array_column($array, 'column', 'key'));
+	assertType("non-empty-array<string, array{column: string, key: string}>", array_column($array, null, 'key'));
 
 	/** @var array<int, array{column?: 'foo', key?: 'bar'}> $array */
 	assertType("array<int, 'foo'>", array_column($array, 'column'));
 	assertType("array<'bar'|int, 'foo'>", array_column($array, 'column', 'key'));
+	assertType("array<'bar'|int, array{column?: 'foo', key?: 'bar'}>", array_column($array, null, 'key'));
 
 	/** @var array<int, array{column1: string, column2: bool}> $array */
 	assertType('array<int, bool|string>', array_column($array, mt_rand(0, 1) === 0 ? 'column1' : 'column2'));
 
 	/** @var non-empty-array<int, array{column: string, key: string}> $array */
 	assertType('non-empty-array<int, string>', array_column($array, 'column'));
 	assertType('non-empty-array<string, string>', array_column($array, 'column', 'key'));
+	assertType('non-empty-array<string, array{column: string, key: string}>', array_column($array, null, 'key'));
 }
 
 function testImprecise(array $array): void {
@@ -55,9 +62,11 @@ function testImprecise(array $array): void {
 	/** @var array{array{column?: 'foo', key: 'bar'}} $array */
 	assertType("array<int, 'foo'>", array_column($array, 'column'));
 	assertType("array<'bar', 'foo'>", array_column($array, 'column', 'key'));
+	assertType("array{bar: array{column?: 'foo', key: 'bar'}}", array_column($array, null, 'key'));
 
 	/** @var array{array{column: 'foo', key?: 'bar'}} $array */
 	assertType("non-empty-array<'bar'|int, 'foo'>", array_column($array, 'column', 'key'));
+	assertType("non-empty-array<'bar'|int, array{column: 'foo', key?: 'bar'}>", array_column($array, null, 'key'));
 
 	/** @var array{array{column: 'foo', key: 'bar'}}|array<int, array<string, string>> $array */
 	assertType('array<int, string>', array_column($array, 'column'));
@@ -72,21 +81,27 @@ function testObjects(array $array): void {
 	/** @var array<int, DOMElement> $array */
 	assertType('array<int, string>', array_column($array, 'nodeName'));
 	assertType('array<string, string>', array_column($array, 'nodeName', 'tagName'));
+	assertType('array<string, DOMElement>', array_column($array, null, 'tagName'));
 	assertType('array<int, mixed>', array_column($array, 'foo'));
 	assertType('array<string, mixed>', array_column($array, 'foo', 'tagName'));
 	assertType('array<string>', array_column($array, 'nodeName', 'foo'));
+	assertType('array<DOMElement>', array_column($array, null, 'foo'));
 
 	/** @var non-empty-array<int, DOMElement> $array */
 	assertType('non-empty-array<int, string>', array_column($array, 'nodeName'));
 	assertType('non-empty-array<string, string>', array_column($array, 'nodeName', 'tagName'));
+	assertType('non-empty-array<string, DOMElement>', array_column($array, null, 'tagName'));
 	assertType('array<int, mixed>', array_column($array, 'foo'));
 	assertType('array<string, mixed>', array_column($array, 'foo', 'tagName'));
 	assertType('non-empty-array<string>', array_column($array, 'nodeName', 'foo'));
+	assertType('non-empty-array<DOMElement>', array_column($array, null, 'foo'));
 
 	/** @var array{DOMElement} $array */
 	assertType('array{string}', array_column($array, 'nodeName'));
 	assertType('non-empty-array<string, string>', array_column($array, 'nodeName', 'tagName'));
+	assertType('non-empty-array<string, DOMElement>', array_column($array, null, 'tagName'));
 	assertType('array<int, mixed>', array_column($array, 'foo'));
 	assertType('array<string, mixed>', array_column($array, 'foo', 'tagName'));
 	assertType('non-empty-array<int|string, string>', array_column($array, 'nodeName', 'foo'));
+	assertType('non-empty-array<int|string, DOMElement>', array_column($array, null, 'foo'));
 }

tests/PHPStan/Analyser/data/bug-6497.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Bug6497;
+
+use function PHPStan\Testing\assertType;
+
+function bug6497(): void {
+	/** @var array<int, array{foo: string, bar: int}> */
+	$array = [
+		['foo' => 'baz', 'bar' => 3],
+	];
+
+	$array2 = array_column($array, null, 'foo');
+
+	assertType('array<string, array{foo: string, bar: int}>', $array2);
+}