Property unset is an impure point

Author: ondrejmirtes

src/Analyser/ImpurePoint.php

@@ -6,7 +6,7 @@
 use PHPStan\Node\VirtualNode;
 
 /**
- * @phpstan-type ImpurePointIdentifier = 'echo'|'die'|'exit'|'propertyAssign'|'methodCall'|'new'|'functionCall'|'include'|'require'|'print'|'eval'|'superglobal'|'yield'|'yieldFrom'|'static'|'global'|'betweenPhpTags'
+ * @phpstan-type ImpurePointIdentifier = 'echo'|'die'|'exit'|'propertyAssign'|'propertyUnset'|'methodCall'|'new'|'functionCall'|'include'|'require'|'print'|'eval'|'superglobal'|'yield'|'yieldFrom'|'static'|'global'|'betweenPhpTags'
  * @api
  */
 class ImpurePoint

src/Analyser/NodeScopeResolver.php

@@ -1687,6 +1687,15 @@ static function (Node $node, Scope $scope) use ($nodeCallback): void {
 						static fn (MutatingScope $scope): ExpressionResult => new ExpressionResult($scope, false, [], []),
 						false,
 					)->getScope();
+				} elseif ($var instanceof PropertyFetch) {
+					$scope = $scope->invalidateExpression($var);
+					$impurePoints[] = new ImpurePoint(
+						$scope,
+						$var,
+						'propertyUnset',
+						'property unset',
+						true,
+					);
 				} else {
 					$scope = $scope->invalidateExpression($var);
 				}

tests/PHPStan/Rules/DeadCode/BetterNoopRuleTest.php

@@ -143,4 +143,9 @@ public function testRuleImpurePoints(): void
 		]);
 	}
 
+	public function testBug11001(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11001.php'], []);
+	}
+
 }

tests/PHPStan/Rules/DeadCode/data/bug-11001.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Bug11001;
+
+class Foo
+{
+
+	/** @var int */
+	public $x;
+
+	/** @var int */
+	public $foo;
+
+	public function doFoo(): void
+	{
+		$x = new self();
+
+		(function () use ($x) {
+			unset($x->foo);
+		})();
+	}
+
+}