Do not warn about ?? on non-$this typed properties without default value

Properties declared as `public int $i;` (without a default value) can be
uninitialized when accessed on external objects, so using ?? on them is valid.
Only warn when the property has a default value (guaranteed initialized).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Rules/IssetCheck.php

@@ -197,6 +197,11 @@ static function (Type $type) use ($typeMessageCallback): ?string {
 
 						return null;
 					}
+
+					$nativeReflection = $propertyReflection->getNativeReflection();
+					if ($nativeReflection !== null && !$nativeReflection->getNativeReflection()->hasDefaultValue()) {
+						return $this->checkUndefined($expr->var, $scope, $operatorDescription, $identifier);
+					}
 				}
 			}
 

tests/PHPStan/Rules/Variables/IssetRuleTest.php

@@ -210,10 +210,6 @@ public function testNativePropertyTypes(): void
 				'Property IssetNativePropertyTypes\Foo::$isAssignedBefore (int) in isset() is not nullable.',
 				20,
 			],
-			[
-				'Property IssetNativePropertyTypes\Foo::$canBeUninitialized (int) in isset() is not nullable.',
-				22,
-			],
 		]);
 	}
 

tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php

@@ -113,10 +113,6 @@ public function testCoalesceRule(): void
 				131,
 			],
 		];
-		$errors[] = [
-			'Property ReflectionClass<object>::$name (class-string<object>) on left side of ?? is not nullable.',
-			136,
-		];
 		$errors[] = [
 			'Variable $foo on left side of ?? is never defined.',
 			141,
@@ -379,7 +375,7 @@ public function testBug14393(): void
 		$this->analyse([__DIR__ . '/data/bug-14393.php'], [
 			[
 				'Property Bug14393\MyClass::$i (int) on left side of ?? is not nullable.',
-				12,
+				17,
 			],
 		]);
 	}

tests/PHPStan/Rules/Variables/data/bug-14393.php

@@ -7,6 +7,15 @@ class MyClass
 	public int $i = 10;
 }
 
+class MyClassUninitialized
+{
+	public int $i;
+}
+
 $o = new MyClass();
 
 var_dump($o->i ?? -1);
+
+$o2 = new MyClassUninitialized();
+
+var_dump($o2->i ?? -1);