Inferred property type for missing assigned property should not be se…

…t to implicit mixed

src/Reflection/Php/PhpClassReflectionExtension.php

@@ -875,11 +875,11 @@ private function collectTraits(\ReflectionClass $class): array
 	private function inferPrivatePropertyType(
 		string $propertyName,
 		MethodReflection $constructor
-	): Type
+	): ?Type
 	{
 		$declaringClassName = $constructor->getDeclaringClass()->getName();
 		if (isset($this->inferClassConstructorPropertyTypesInProcess[$declaringClassName])) {
-			return new MixedType();
+			return null;
 		}
 		$this->inferClassConstructorPropertyTypesInProcess[$declaringClassName] = true;
 		$propertyTypes = $this->inferAndCachePropertyTypes($constructor);
@@ -888,7 +888,7 @@ private function inferPrivatePropertyType(
 			return $propertyTypes[$propertyName];
 		}
 
-		return new MixedType();
+		return null;
 	}
 
 	/**

tests/PHPStan/Rules/PhpDoc/IncompatiblePropertyPhpDocTypeRuleTest.php

@@ -125,4 +125,13 @@ public function testPromotedProperties(): void
 		]);
 	}
 
+	public function testBug4227(): void
+	{
+		if (PHP_VERSION_ID < 70400 && !self::$useStaticReflectionProvider) {
+			$this->markTestSkipped('Test requires PHP 7.4.');
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-4227.php'], []);
+	}
+
 }

tests/PHPStan/Rules/PhpDoc/data/bug-4227.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Bug4227;
+
+class Foo
+{
+	private bool $property;
+	private int $count = 0;
+	private ?string $string = null;
+
+	public function __construct(bool $property)
+	{
+		$this->property = $property;
+	}
+
+	public function count(): int
+	{
+		return $this->count;
+	}
+}