Support ArrayAccess in AppendedArrayItemTypeRule

Author: herndlm

src/Rules/Arrays/AppendedArrayItemTypeRule.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Arrays;
 
+use ArrayAccess;
 use PhpParser\Node;
 use PhpParser\Node\Expr\ArrayDimFetch;
 use PhpParser\Node\Expr\Assign;
@@ -13,6 +14,7 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Rules\RuleLevelHelper;
 use PHPStan\Type\ArrayType;
+use PHPStan\Type\ObjectType;
 use PHPStan\Type\VerbosityLevel;
 use function sprintf;
 
@@ -67,7 +69,7 @@ public function processNode(Node $node, Scope $scope): array
 		}
 
 		$assignedToType = $propertyReflection->getWritableType();
-		if (!($assignedToType instanceof ArrayType)) {
+		if (!($assignedToType instanceof ArrayType) && !(new ObjectType(ArrayAccess::class))->isSuperTypeOf($assignedToType)->yes()) {
 			return [];
 		}
 
@@ -77,7 +79,7 @@ public function processNode(Node $node, Scope $scope): array
 			$assignedValueType = $scope->getType($node);
 		}
 
-		$itemType = $assignedToType->getItemType();
+		$itemType = $assignedToType->getIterableValueType();
 		if (!$this->ruleLevelHelper->accepts($itemType, $assignedValueType, $scope->isDeclareStrictTypes())) {
 			$verbosityLevel = VerbosityLevel::getRecommendedLevelByType($itemType, $assignedValueType);
 			return [

src/Type/ObjectType.php

@@ -746,6 +746,15 @@ public function getIterableValueType(): Type
 			return new MixedType();
 		}
 
+		if ($this->isInstanceOf(ArrayAccess::class)->yes()) {
+			$tValue = GenericTypeVariableResolver::getType($this, ArrayAccess::class, 'TValue');
+			if ($tValue !== null) {
+				return $tValue;
+			}
+
+			return new MixedType();
+		}
+
 		return new ErrorType();
 	}
 

tests/PHPStan/Rules/Arrays/AppendedArrayItemTypeRuleTest.php

@@ -58,6 +58,18 @@ public function testAppendedArrayItemType(): void
 					'Array (array<AppendedArrayItem\Lorem>) does not accept AppendedArrayItem\Baz.',
 					79,
 				],
+				[
+					'Array (ArrayAccess<int, string>) does not accept int.',
+					95,
+				],
+				[
+					'Array (ArrayAccess<int, string>&Countable) does not accept int.',
+					96,
+				],
+				[
+					'Array (ArrayAccess<int, string>&Countable&iterable<int, string>) does not accept int.',
+					97,
+				],
 			]
 		);
 	}

tests/PHPStan/Rules/Arrays/data/appended-array-item.php

@@ -78,3 +78,22 @@ function (Lorem $lorem)
 {
 	$lorem->staticProperty[] = new Baz();
 };
+
+class ArrayAccess
+{
+	/** @var \ArrayAccess<int, string> */
+	private $collection1;
+
+	/** @var \ArrayAccess<int, string>&\Countable */
+	private $collection2;
+
+	/** @var \ArrayAccess<int, string>&\Countable&iterable<int, string> */
+	private $collection3;
+
+	public function doFoo()
+	{
+		$this->collection1[] = 1;
+		$this->collection2[] = 2;
+		$this->collection3[] = 3;
+	}
+}