Fix for handling non-stringable types in dynamic property access

Author: zonuexe

src/Rules/Properties/AccessPropertiesCheck.php

@@ -41,13 +41,20 @@ public function __construct(
 	 */
 	public function check(PropertyFetch $node, Scope $scope, bool $write): array
 	{
+		$errors = [];
 		if ($node->name instanceof Identifier) {
 			$names = [$node->name->name];
 		} else {
-			$names = array_map(static fn (ConstantStringType $type): string => $type->getValue(), $scope->getType($node->name)->getConstantStrings());
+			$fetchType = $scope->getType($node->name);
+			$names = array_map(static fn (ConstantStringType $type): string => $type->getValue(), $fetchType->getConstantStrings());
+			$fetchStringType = $fetchType->toString();
+			if (!$fetchStringType->isString()->yes()) {
+				$errors[] = RuleErrorBuilder::message(sprintf('Cannot access property with a non-stringable type %s.', $fetchType->describe(VerbosityLevel::typeOnly())))
+					->identifier('property.fetchInvalidExpression')
+					->build();
+			}
 		}
 
-		$errors = [];
 		foreach ($names as $name) {
 			$errors = array_merge($errors, $this->processSingleProperty($scope, $node, $name, $write));
 		}

src/Rules/Properties/AccessStaticPropertiesRule.php

@@ -51,13 +51,20 @@ public function getNodeType(): string
 
 	public function processNode(Node $node, Scope $scope): array
 	{
+		$errors = [];
 		if ($node->name instanceof Node\VarLikeIdentifier) {
 			$names = [$node->name->name];
 		} else {
-			$names = array_map(static fn (ConstantStringType $type): string => $type->getValue(), $scope->getType($node->name)->getConstantStrings());
+			$fetchType = $scope->getType($node->name);
+			$names = array_map(static fn (ConstantStringType $type): string => $type->getValue(), $fetchType->getConstantStrings());
+			$fetchStringType = $fetchType->toString();
+			if (!$fetchStringType->isString()->yes()) {
+				$errors[] = RuleErrorBuilder::message(sprintf('Cannot access static property with a non-stringable type %s.', $fetchType->describe(VerbosityLevel::typeOnly())))
+					->identifier('property.fetchInvalidExpression')
+					->build();
+			}
 		}
 
-		$errors = [];
 		foreach ($names as $name) {
 			$errors = array_merge($errors, $this->processSingleProperty($scope, $node, $name));
 		}

tests/PHPStan/Rules/Properties/AccessPropertiesRuleTest.php

@@ -344,6 +344,31 @@ public function testAccessPropertiesOnThisOnly(): void
 		);
 	}
 
+	public function testBug9475(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkUnionTypes = false;
+		$this->checkDynamicProperties = false;
+		$this->analyse([__DIR__ . '/data/bug-9475.php'], [
+			[
+				'Cannot access property with a non-stringable type $this(Bug9475\Properties).',
+				12,
+			],
+			[
+				'Cannot access property with a non-stringable type $this(Bug9475\Properties).',
+				13,
+			],
+			[
+				'Cannot access property with a non-stringable type object.',
+				14,
+			],
+			[
+				'Cannot access property with a non-stringable type array.',
+				15,
+			],
+		]);
+	}
+
 	public function testBug12692(): void
 	{
 		$this->checkThisOnly = false;

tests/PHPStan/Rules/Properties/AccessStaticPropertiesRuleTest.php

@@ -309,4 +309,26 @@ public function testBug8333(): void
 		]);
 	}
 
+	public function testBug9475(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-9475.php'], [
+			[
+				'Cannot access static property with a non-stringable type $this(Bug9475\Properties).',
+				23,
+			],
+			[
+				'Cannot access static property with a non-stringable type $this(Bug9475\Properties).',
+				24,
+			],
+			[
+				'Cannot access static property with a non-stringable type object.',
+				25,
+			],
+			[
+				'Cannot access static property with a non-stringable type array.',
+				26,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-9475.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9475;
+
+use Stringable;
+
+final class Properties
+{
+
+	public function testProperties(string $name, Stringable $stringable, object $object, array $array): void
+	{
+		echo 'Hello, ' . $this->{$this}->name;
+		echo 'Hello, ' . $this->$this->name;
+		echo 'Hello, ' . $this->$object;
+		echo 'Hello, ' . $this->$array;
+
+		echo 'Hello, ' . $this->$name; // valid
+		echo 'Hello, ' . $this->$stringable; // valid
+	}
+
+	public function testStaticProperties(string $name, Stringable $stringable, object $object, array $array): void
+	{
+		echo 'Hello, ' . self::${$this}->name;
+		echo 'Hello, ' . self::$$this->name;
+		echo 'Hello, ' . self::$$object;
+		echo 'Hello, ' . self::$$array;
+
+		echo 'Hello, ' . self::$$name; // valid
+		echo 'Hello, ' . self::$$stringable; // valid
+	}
+
+}