From 702ddcd7805ba08c0765bdf0930beaef0e6b4fc1 Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Tue, 14 May 2024 14:02:23 +0200
Subject: [PATCH] Property unset is an impure point

---
 src/Analyser/ImpurePoint.php                  |  2 +-
 src/Analyser/NodeScopeResolver.php            |  9 ++++++++
 .../Rules/DeadCode/BetterNoopRuleTest.php     |  5 ++++
 .../PHPStan/Rules/DeadCode/data/bug-11001.php | 23 +++++++++++++++++++
 4 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Rules/DeadCode/data/bug-11001.php

diff --git a/src/Analyser/ImpurePoint.php b/src/Analyser/ImpurePoint.php
index e5f89255ed..59fccfac36 100644
--- a/src/Analyser/ImpurePoint.php
+++ b/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
diff --git a/src/Analyser/NodeScopeResolver.php b/src/Analyser/NodeScopeResolver.php
index 6e253a71db..9abf5a6520 100644
--- a/src/Analyser/NodeScopeResolver.php
+++ b/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);
 				}
diff --git a/tests/PHPStan/Rules/DeadCode/BetterNoopRuleTest.php b/tests/PHPStan/Rules/DeadCode/BetterNoopRuleTest.php
index dd472321ea..6a0780ad36 100644
--- a/tests/PHPStan/Rules/DeadCode/BetterNoopRuleTest.php
+++ b/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'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/DeadCode/data/bug-11001.php b/tests/PHPStan/Rules/DeadCode/data/bug-11001.php
new file mode 100644
index 0000000000..a5b8182222
--- /dev/null
+++ b/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);
+		})();
+	}
+
+}