UselessPrivatePropertyNullabilityRule: fix when mixed is assigned (#103)

Author: janedbal

src/Rule/UselessPrivatePropertyNullabilityRule.php

@@ -12,6 +12,7 @@
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleError;
 use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Type\NullType;
 use PHPStan\Type\TypeCombinator;
 use ShipMonk\PHPStan\Visitor\ClassPropertyAssignmentVisitor;
 
@@ -62,9 +63,10 @@ public function processNode(Node $node, Scope $scope): array
                 continue;
             }
 
+            $nullType = new NullType();
             $assignedType = $propertyUsage->getScope()->getType($assignedExpr);
 
-            if (TypeCombinator::containsNull($assignedType)) {
+            if ($assignedType->accepts($nullType, $scope->isDeclareStrictTypes())->yes()) {
                 $nullabilityNeeded[$propertyName] = true;
             }
         }

tests/Rule/data/UselessPrivatePropertyNullabilityRule/code.php

@@ -10,6 +10,8 @@ class ExampleClass
 
     private ?int $isPrivate; // error: Property UselessPrivatePropertyNullabilityRule\ExampleClass::isPrivate is defined as nullable, but null is never assigned
 
+    private ?int $isPrivateMixedAssigned;
+
     private ?int $isPrivateAssigned;
 
     private ?int $isPrivateWithConditionalAssignment;
@@ -24,6 +26,7 @@ class ExampleClass
     private $isUninitializedWithoutTypehint;
 
     public function __construct(
+        mixed $mixed,
         int $isPublic,
         int $isProtected,
         int $isPrivate,
@@ -35,6 +38,7 @@ public function __construct(
         $this->isPublic = $isPublic;
         $this->isProtected = $isProtected;
         $this->isPrivate = $isPrivate;
+        $this->isPrivateMixedAssigned = $mixed;
         $this->isPrivateWithConditionalAssignment = $isPrivateWithConditionalAssignment === 0 ? null : 1;
         $this->isPrivateWithDefaultNull = $isPrivateWithDefaultNull;
         $this->isPrivateWithDefaultNotNull = $isPrivateWithDefaultNotNull;