Do not use instanceof ThisType as it can be unreliable in case of intersection types

Author: ondrejmirtes

src/Node/ClassStatementsGatherer.php

@@ -17,7 +17,7 @@
 use PHPStan\Node\Property\PropertyWrite;
 use PHPStan\Reflection\ClassReflection;
 use PHPStan\ShouldNotHappenException;
-use PHPStan\Type\ThisType;
+use PHPStan\Type\TypeUtils;
 use function count;
 use function in_array;
 
@@ -220,7 +220,7 @@ private function tryToApplyPropertyReads(Expr\FuncCall $node, Scope $scope): voi
 		}
 
 		$firstArgValue = $args[0]->value;
-		if (!$scope->getType($firstArgValue) instanceof ThisType) {
+		if (TypeUtils::findThisType($scope->getType($firstArgValue)) === null) {
 			return;
 		}
 

src/Rules/Properties/ReadOnlyByPhpDocPropertyAssignRule.php

@@ -10,7 +10,7 @@
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\ShouldNotHappenException;
-use PHPStan\Type\ThisType;
+use PHPStan\Type\TypeUtils;
 use function in_array;
 use function sprintf;
 use function strtolower;
@@ -76,7 +76,7 @@ public function processNode(Node $node, Scope $scope): array
 				in_array($scopeMethod->getName(), $this->constructorsHelper->getConstructors($scopeClassReflection), true)
 				|| strtolower($scopeMethod->getName()) === '__unserialize'
 			) {
-				if (!$scope->getType($propertyFetch->var) instanceof ThisType) {
+				if (TypeUtils::findThisType($scope->getType($propertyFetch->var)) === null) {
 					$errors[] = RuleErrorBuilder::message(sprintf('@readonly property %s::$%s is not assigned on $this.', $declaringClass->getDisplayName(), $propertyReflection->getName()))->build();
 				}
 

src/Rules/Properties/ReadOnlyPropertyAssignRule.php

@@ -10,7 +10,7 @@
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\ShouldNotHappenException;
-use PHPStan\Type\ThisType;
+use PHPStan\Type\TypeUtils;
 use function in_array;
 use function sprintf;
 use function strtolower;
@@ -76,7 +76,7 @@ public function processNode(Node $node, Scope $scope): array
 				in_array($scopeMethod->getName(), $this->constructorsHelper->getConstructors($scopeClassReflection), true)
 				|| strtolower($scopeMethod->getName()) === '__unserialize'
 			) {
-				if (!$scope->getType($propertyFetch->var) instanceof ThisType) {
+				if (TypeUtils::findThisType($scope->getType($propertyFetch->var)) === null) {
 					$errors[] = RuleErrorBuilder::message(sprintf('Readonly property %s::$%s is not assigned on $this.', $declaringClass->getDisplayName(), $propertyReflection->getName()))->build();
 				}
 

src/Type/Php/GetClassDynamicReturnTypeExtension.php

@@ -17,9 +17,9 @@
 use PHPStan\Type\ObjectType;
 use PHPStan\Type\ObjectWithoutClassType;
 use PHPStan\Type\StaticType;
-use PHPStan\Type\ThisType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeTraverser;
+use PHPStan\Type\TypeUtils;
 use PHPStan\Type\UnionType;
 use function count;
 
@@ -49,7 +49,7 @@ public function getTypeFromFunctionCall(FunctionReflection $functionReflection,
 
 		$argType = $scope->getType($args[0]->value);
 
-		if ($scope->isInTrait() && $argType instanceof ThisType) {
+		if ($scope->isInTrait() && TypeUtils::findThisType($argType) !== null) {
 			return new ClassStringType();
 		}