Fix phpstan/phpstan#11844: false property.unusedType for nullable generic property assigned inside null check

- Used declared property type from reflection instead of scope-narrowed type in NewHandler
- When `new WeakMap()` was assigned inside `if ($this->map === null)`, scope returned narrowed `null` type
- TypeCombinator::removeNull on `null` yielded `never`, making TooWideTypeCheck think WeakMap was never assigned
- New regression test in tests/PHPStan/Rules/TooWideTypehints/data/bug-11844.php

Author: github-actions[bot]

src/Analyser/ExprHandler/NewHandler.php

@@ -416,10 +416,13 @@ private function exactInstantiation(MutatingScope $scope, New_ $node, Name $clas
 				$classTemplateTypes = $traverser->getClassTemplateTypes();
 
 				if (count($classTemplateTypes) === count($originalClassTemplateTypes)) {
-					$propertyType = TypeCombinator::removeNull($scope->getType($assignedToProperty));
-					$nonFinalObjectType = $isStatic ? new StaticType($nonFinalClassReflection) : new ObjectType($resolvedClassName, classReflection: $nonFinalClassReflection);
-					if ($nonFinalObjectType->isSuperTypeOf($propertyType)->yes()) {
-						return $propertyType;
+					$propertyType = $this->resolveAssignedPropertyDeclaredType($assignedToProperty, $scope);
+					if ($propertyType !== null) {
+						$propertyType = TypeCombinator::removeNull($propertyType);
+						$nonFinalObjectType = $isStatic ? new StaticType($nonFinalClassReflection) : new ObjectType($resolvedClassName, classReflection: $nonFinalClassReflection);
+						if ($nonFinalObjectType->isSuperTypeOf($propertyType)->yes()) {
+							return $propertyType;
+						}
 					}
 				}
 			}
@@ -590,4 +593,25 @@ classReflection: $classReflection->withTypes($types)->asFinal(),
 		return TypeTraverser::map($newGenericType, new GenericTypeTemplateTraverser($resolvedTemplateTypeMap));
 	}
 
+	private function resolveAssignedPropertyDeclaredType(Node\Expr $propertyFetch, MutatingScope $scope): ?Type
+	{
+		if ($propertyFetch instanceof Node\Expr\PropertyFetch && $propertyFetch->name instanceof Node\Identifier) {
+			$holderType = $scope->getType($propertyFetch->var);
+			$propertyName = $propertyFetch->name->name;
+			if ($holderType->hasInstanceProperty($propertyName)->yes()) {
+				return $holderType->getInstanceProperty($propertyName, $scope)->getReadableType();
+			}
+		} elseif ($propertyFetch instanceof Node\Expr\StaticPropertyFetch && $propertyFetch->name instanceof Node\VarLikeIdentifier && $propertyFetch->class instanceof Name) {
+			$className = $scope->resolveName($propertyFetch->class);
+			if ($this->reflectionProvider->hasClass($className)) {
+				$classRefl = $this->reflectionProvider->getClass($className);
+				$propertyName = $propertyFetch->name->name;
+				if ($classRefl->hasStaticProperty($propertyName)) {
+					return $classRefl->getStaticProperty($propertyName)->getReadableType();
+				}
+			}
+		}
+		return null;
+	}
+
 }

tests/PHPStan/Rules/TooWideTypehints/TooWidePropertyTypeRuleTest.php

@@ -138,4 +138,10 @@ public function testBug13624(): void
 		$this->analyse([__DIR__ . '/data/bug-13624.php'], []);
 	}
 
+	#[RequiresPhp('>= 8.0')]
+	public function testBug11844(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11844.php'], []);
+	}
+
 }

tests/PHPStan/Rules/TooWideTypehints/data/bug-11844.php

@@ -0,0 +1,48 @@
+<?php // lint >= 8.0
+
+declare(strict_types = 1);
+
+namespace Bug11844;
+
+class StaticPropertyCase
+{
+	/**
+	 * @var \WeakMap<object, string>|null
+	 */
+	private static ?\WeakMap $map = null;
+
+	public static function init(): void
+	{
+		if (self::$map === null) {
+			self::$map = new \WeakMap();
+		}
+	}
+}
+
+class InstancePropertyCase
+{
+	/**
+	 * @var \WeakMap<object, string>|null
+	 */
+	private ?\WeakMap $map = null;
+
+	public function init(): void
+	{
+		if ($this->map === null) {
+			$this->map = new \WeakMap();
+		}
+	}
+}
+
+class DirectAssignCase
+{
+	/**
+	 * @var \WeakMap<object, string>|null
+	 */
+	private ?\WeakMap $map = null;
+
+	public function initAlways(): void
+	{
+		$this->map = new \WeakMap();
+	}
+}