Fix for handling non-stringable types in dynamic class constant access

Author: zonuexe

Diff for: src/Rules/Classes/ClassConstantRule.php

@@ -11,6 +11,7 @@
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Rules\ClassNameCheck;
 use PHPStan\Rules\ClassNameNodePair;
+use PHPStan\Rules\IdentifierRuleError;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Rules\RuleLevelHelper;
@@ -20,6 +21,7 @@
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\VerbosityLevel;
+use function array_map;
 use function array_merge;
 use function in_array;
 use function sprintf;
@@ -47,11 +49,32 @@ public function getNodeType(): string
 
 	public function processNode(Node $node, Scope $scope): array
 	{
-		if (!$node->name instanceof Node\Identifier) {
-			return [];
+		$errors = [];
+		if ($node->name instanceof Node\Identifier) {
+			$constantNames = [$node->name->name];
+		} else {
+			$fetchType = $scope->getType($node->name);
+			$constantNames = array_map(static fn ($type): string => $type->getValue(), $fetchType->getConstantStrings());
+			$fetchStringType = $fetchType->toString();
+			if (!$fetchStringType->isString()->yes()) {
+				$errors[] = RuleErrorBuilder::message(sprintf('Cannot fetch class constant with a non-stringable type %s.', $fetchType->describe(VerbosityLevel::typeOnly())))
+					->identifier('classConstant.fetchInvalidExpression')
+					->build();
+			}
+		}
+
+		foreach ($constantNames as $constantName) {
+			$errors = array_merge($errors, $this->processSingleClassConstFetch($scope, $node, $constantName));
 		}
-		$constantName = $node->name->name;
 
+		return $errors;
+	}
+
+	/**
+	 * @return list<IdentifierRuleError>
+	 */
+	private function processSingleClassConstFetch(Scope $scope, ClassConstFetch $node, string $constantName): array
+	{
 		$class = $node->class;
 		$messages = [];
 		if ($class instanceof Node\Name) {

Diff for: tests/PHPStan/Rules/Classes/ClassConstantRuleTest.php

@@ -435,4 +435,28 @@ public function testClassConstantAccessedOnTrait(): void
 		]);
 	}
 
+	public function testBug9475(): void
+	{
+		if (PHP_VERSION_ID < 80200) {
+			$this->markTestSkipped('Test requires PHP 8.2.');
+		}
+
+		$this->phpVersion = PHP_VERSION_ID;
+
+		$this->analyse([__DIR__ . '/data/bug-9475.php'], [
+			[
+				'Cannot fetch class constant with a non-stringable type $this(Bug9475\HelloWorld).',
+				12,
+			],
+			[
+				'Cannot fetch class constant with a non-stringable type object.',
+				13,
+			],
+			[
+				'Cannot fetch class constant with a non-stringable type array.',
+				14,
+			],
+		]);
+	}
+
 }

Diff for: tests/PHPStan/Rules/Classes/data/bug-9475.php

@@ -0,0 +1,20 @@
+<?php declare(strict_types = 1);
+
+namespace Bug9475;
+
+use Stringable;
+
+final class HelloWorld
+{
+
+	public function testStaticMethods(string $name, Stringable $stringable, object $object, array $array): void
+	{
+		echo 'Hello, ' . self::{$this};
+		echo 'Hello, ' . self::{$object};
+		echo 'Hello, ' . self::{$array};
+
+		echo 'Hello, ' . self::{$name}; // valid
+		echo 'Hello, ' . self::{$stringable}; // valid
+	}
+
+}