Fix isset() false positive for methods called from constructor

When a method that assigns a property is called from the constructor,
PHPStan merges the property initialization state back into the
constructor scope. This caused a false positive when the same method
used isset() to check if the property was already initialized, because
the preserved constructor scope incorrectly marked the property as
initialized when entering the method.

The fix removes PropertyInitializationExpr entries for properties that
a method itself initializes, when the method was called from the
constructor. This generalizes the property hook fix to also work for
regular methods.

Also extracts exitPropertyInitialization() on MutatingScope to share
the logic between property hooks and regular methods.

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

Author: phpstan-bot

src/Analyser/MutatingScope.php

@@ -1608,9 +1608,7 @@ public function enterPropertyHook(
 		);
 
 		if ($hookName === 'set') {
-			$initExprKey = $this->getNodeKey(new PropertyInitializationExpr($propertyName));
-			unset($scope->expressionTypes[$initExprKey]);
-			unset($scope->nativeExpressionTypes[$initExprKey]);
+			$scope->exitPropertyInitialization($propertyName);
 		}
 
 		return $scope;
@@ -2840,6 +2838,15 @@ public function assignInitializedProperty(Type $fetchedOnType, string $propertyN
 		return $this->assignExpression(new PropertyInitializationExpr($propertyName), new MixedType(), new MixedType());
 	}
 
+	public function exitPropertyInitialization(string $propertyName): self
+	{
+		$initExprKey = $this->getNodeKey(new PropertyInitializationExpr($propertyName));
+		unset($this->expressionTypes[$initExprKey]);
+		unset($this->nativeExpressionTypes[$initExprKey]);
+
+		return $this;
+	}
+
 	public function invalidateExpression(Expr $expressionToInvalidate, bool $requireMoreCharacters = false, ?ClassReflection $invalidatingClass = null): self
 	{
 		$expressionTypes = $this->expressionTypes;

src/Analyser/NodeScopeResolver.php

@@ -712,6 +712,20 @@ public function processStmtNode(
 
 			$classReflection = $scope->getClassReflection();
 
+			if (!$isConstructor && !$stmt->isStatic()) {
+				$stackName = sprintf('%s::%s', $classReflection->getName(), $stmt->name->toString());
+				$calledMethodScope = $this->calledMethodResults[$stackName] ?? null;
+				if ($calledMethodScope !== null) {
+					foreach ($calledMethodScope->expressionTypes as $typeHolder) {
+						$expr = $typeHolder->getExpr();
+						if (!$expr instanceof PropertyInitializationExpr) {
+							continue;
+						}
+						$methodScope = $methodScope->exitPropertyInitialization($expr->getPropertyName());
+					}
+				}
+			}
+
 			if ($isConstructor) {
 				foreach ($stmt->params as $param) {
 					if ($param->flags === 0 && $param->hooks === []) {

tests/PHPStan/Rules/Variables/IssetRuleTest.php

@@ -570,4 +570,11 @@ public function testBug13473(): void
 		$this->analyse([__DIR__ . '/data/bug-13473.php'], []);
 	}
 
+	public function testBug13473Method(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+
+		$this->analyse([__DIR__ . '/data/bug-13473-method.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Variables/data/bug-13473-method.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Bug13473Method;
+
+class Foo {
+    private int $bar;
+
+    public function __construct(int $bar)
+    {
+        $this->setBar($bar);
+    }
+
+	public function setBar(int $bar): void
+	{
+		if (isset($this->bar)) {
+			throw new \Exception('bar is set');
+		}
+		$this->bar = $bar;
+	}
+}