Preserve array type through dependent offset assignment with template keys

src/Analyser/ExprHandler/AssignHandler.php

@@ -58,15 +58,18 @@
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\ConstantTypeHelper;
 use PHPStan\Type\ErrorType;
+use PHPStan\Type\Generic\TemplateType;
 use PHPStan\Type\IntegerRangeType;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectType;
+use PHPStan\Type\OffsetAccessType;
 use PHPStan\Type\StaticTypeFactory;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypeUtils;
 use TypeError;
+use function array_key_exists;
 use function array_key_last;
 use function array_merge;
 use function array_pop;
@@ -439,7 +442,28 @@
 			$offsetValueType = $varType;
 			$offsetNativeValueType = $varNativeType;
 
-			[$valueToWrite, $additionalExpressions] = $this->produceArrayDimFetchAssignValueToWrite($dimFetchStack, $offsetTypes, $offsetValueType, $valueToWrite, $scope);
+			$dependentPreserved = false;
+			if (
+				count($dimFetchStack) === 1
+				&& count($offsetTypes) === 1
+				&& $offsetTypes[0][0] !== null
+				&& TypeUtils::containsTemplateType($offsetTypes[0][0])
+			) {
+				$rawValueType = $this->getRawExpressionType($scope, $assignedExpr);
+				if (
+					$rawValueType instanceof OffsetAccessType
+					&& $this->isSameTemplateOffset($rawValueType->getAccessedOffset(), $offsetTypes[0][0])
+					&& $rawValueType->getAccessedType()->isSuperTypeOf($offsetValueType)->yes()
+				) {
+					$dependentPreserved = true;
+					$additionalExpressions = [[$dimFetchStack[0], $valueToWrite]];
+					$valueToWrite = $offsetValueType;
+				}
+			}
+
+			if (!$dependentPreserved) {
+				[$valueToWrite, $additionalExpressions] = $this->produceArrayDimFetchAssignValueToWrite($dimFetchStack, $offsetTypes, $offsetValueType, $valueToWrite, $scope);
+			}
 
 			if (!$offsetValueType->equals($offsetNativeValueType) || !$valueToWrite->equals($nativeValueToWrite)) {
 				[$nativeValueToWrite, $additionalNativeExpressions] = $this->produceArrayDimFetchAssignValueToWrite($dimFetchStack, $offsetNativeTypes, $offsetNativeValueType, $nativeValueToWrite, $scope);
@@ -1258,4 +1282,27 @@
 		return false;
 	}
 
+	private function isSameTemplateOffset(Type $a, Type $b): bool
+	{
+		if ($a->equals($b)) {
+			return true;
+		}
+
+		if ($a instanceof TemplateType && $b instanceof TemplateType) {
+			return $a->getScope()->equals($b->getScope()) && $a->getName() === $b->getName();
+		}
+
+		return false;
+	}
+
+	private function getRawExpressionType(MutatingScope $scope, Expr $expr): ?Type
+	{
+		$key = $scope->getNodeKey($expr);
+		if (!array_key_exists($key, $scope->expressionTypes)) {
+			return null;
+		}
+
+		return $scope->expressionTypes[$key]->getType();
+	}
+
 }

src/Type/OffsetAccessType.php

@@ -24,6 +24,16 @@ public function __construct(
 	{
 	}
 
+	public function getAccessedType(): Type
+	{
+		return $this->type;
+	}
+
+	public function getAccessedOffset(): Type
+	{
+		return $this->offset;
+	}
+
 	public function getReferencedClasses(): array
 	{
 		return array_merge(

tests/PHPStan/Analyser/AnalyserIntegrationTest.php

@@ -824,9 +824,8 @@ public function testBug7215(): void
 
 	public function testBug7094(): void
 	{
-		// false positive
 		$errors = $this->runAnalyse(__DIR__ . '/data/bug-7094.php');
-		$this->assertCount(6, $errors);
+		$this->assertCount(5, $errors);
 
 		$this->assertSame('Parameter #2 $val of method Bug7094\Foo::setAttribute() contains unresolvable type.', $errors[0]->getMessage());
 		$this->assertSame(74, $errors[0]->getLine());
@@ -838,9 +837,6 @@ public function testBug7094(): void
 		$this->assertSame(78, $errors[3]->getLine());
 		$this->assertSame('Return type of call to method Bug7094\Foo::getAttribute() contains unresolvable type.', $errors[4]->getMessage());
 		$this->assertSame(79, $errors[4]->getLine());
-
-		$this->assertSame('Parameter #1 $attr of method Bug7094\Foo::setAttributes() expects array{foo?: string, bar?: 5|6|7, baz?: bool}, non-empty-array<\'bar\'|\'baz\'|\'foo\'|K of string, 5|6|7|bool|string> given.', $errors[5]->getMessage());
-		$this->assertSame(29, $errors[5]->getLine());
 	}
 
 	#[RequiresPhp('>= 8.0.0')]

tests/PHPStan/Analyser/nsrt/bug-7380.php

@@ -0,0 +1,64 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7380;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @phpstan-type Attrs array{foo?: string, bar?: 5|6|7, baz?: bool}
+ */
+final class Foo {
+
+	/**
+	 * @template K of key-of<Attrs>
+	 * @param K $key
+	 * @param Attrs[K] $val
+	 */
+	public function setAttribute(string $key, mixed $val): void
+	{
+		$attr = $this->getAttributes();
+		$attr[$key] = $val;
+		assertType('array{foo?: string, bar?: 5|6|7, baz?: bool}', $attr);
+		$this->setAttributes($attr);
+	}
+
+	/** @return Attrs */
+	public function getAttributes(): array
+	{
+		return [];
+	}
+
+	/** @param Attrs $attr */
+	public function setAttributes(array $attr): void
+	{
+	}
+}
+
+/**
+ * @template T of array<string, mixed>
+ */
+final class GenericBar {
+
+	/**
+	 * @template K of key-of<T>
+	 * @param K $key
+	 * @param T[K] $val
+	 */
+	public function setAttribute(string $key, mixed $val): void
+	{
+		$attr = $this->getAttributes();
+		$attr[$key] = $val;
+		$this->setAttributes($attr);
+	}
+
+	/** @return T */
+	public function getAttributes(): array
+	{
+		return [];
+	}
+
+	/** @param T $attr */
+	public function setAttributes(array $attr): void
+	{
+	}
+}