LocalTypeAliasesRule: report invalid type alias names

Author: jiripudil

src/Rules/Classes/LocalTypeAliasesRule.php

@@ -6,10 +6,13 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Node\InClassNode;
 use PHPStan\PhpDoc\TypeNodeResolver;
+use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Type\ErrorType;
+use PHPStan\Type\Generic\TemplateType;
+use PHPStan\Type\ObjectType;
 use PHPStan\Type\TypeTraverser;
 
 /**
@@ -115,6 +118,17 @@ public function processNode(Node $node, Scope $scope): array
 				continue;
 			}
 
+			if ($nameScope !== null) {
+				$aliasNameResolvedType = $this->typeNodeResolver->resolve(new IdentifierTypeNode($aliasName), $nameScope);
+				if (!($aliasNameResolvedType instanceof ObjectType)
+					&& !($aliasNameResolvedType instanceof TemplateType) // aliases take precedence over type parameters, this is reported by other rules using TemplateTypeCheck
+					|| in_array($aliasName, ['self', 'parent'], true)
+				) {
+					$errors[] = RuleErrorBuilder::message(sprintf('Type alias has an invalid name: %s.', $aliasName))->build();
+					continue;
+				}
+			}
+
 			$resolvedType = $typeAliasTag->getTypeAlias()->resolve($this->typeNodeResolver);
 			$foundError = false;
 			TypeTraverser::map($resolvedType, static function (\PHPStan\Type\Type $type, callable $traverse) use (&$errors, &$foundError, $aliasName): \PHPStan\Type\Type {

tests/PHPStan/Rules/Classes/LocalTypeAliasesRuleTest.php

@@ -26,55 +26,59 @@ public function testRule(): void
 		$this->analyse([__DIR__ . '/data/local-type-aliases.php'], [
 			[
 				'Type alias ExistingClassAlias already exists as a class in scope of LocalTypeAliases\Bar.',
-				22,
+				23,
 			],
 			[
 				'Type alias GlobalTypeAlias already exists as a global type alias.',
-				22,
+				23,
+			],
+			[
+				'Type alias has an invalid name: int.',
+				23,
 			],
 			[
 				'Circular definition detected in type alias RecursiveTypeAlias.',
-				22,
+				23,
 			],
 			[
 				'Circular definition detected in type alias CircularTypeAlias1.',
-				22,
+				23,
 			],
 			[
 				'Circular definition detected in type alias CircularTypeAlias2.',
-				22,
+				23,
 			],
 			[
 				'Cannot import type alias ImportedAliasFromNonClass: class LocalTypeAliases\int does not exist.',
-				37,
+				38,
 			],
 			[
 				'Cannot import type alias ImportedAliasFromUnknownClass: class LocalTypeAliases\UnknownClass does not exist.',
-				37,
+				38,
 			],
 			[
 				'Cannot import type alias ImportedUnknownAlias: type alias does not exist in LocalTypeAliases\Foo.',
-				37,
+				38,
 			],
 			[
 				'Type alias ExistingClassAlias already exists as a class in scope of LocalTypeAliases\Baz.',
-				37,
+				38,
 			],
 			[
 				'Type alias GlobalTypeAlias already exists as a global type alias.',
-				37,
+				38,
 			],
 			[
 				'Type alias OverwrittenTypeAlias overwrites an imported type alias of the same name.',
-				37,
+				38,
 			],
 			[
 				'Circular definition detected in type alias CircularTypeAliasImport2.',
-				37,
+				38,
 			],
 			[
 				'Circular definition detected in type alias CircularTypeAliasImport1.',
-				45,
+				46,
 			],
 		]);
 	}

tests/PHPStan/Rules/Classes/data/local-type-aliases.php

@@ -15,6 +15,7 @@ class Foo
  * @phpstan-type LocalTypeAlias int
  * @phpstan-type ExistingClassAlias \stdClass
  * @phpstan-type GlobalTypeAlias bool
+ * @phpstan-type int \stdClass
  * @phpstan-type RecursiveTypeAlias RecursiveTypeAlias[]
  * @phpstan-type CircularTypeAlias1 CircularTypeAlias2
  * @phpstan-type CircularTypeAlias2 CircularTypeAlias1
@@ -45,3 +46,11 @@ class Baz
 class Qux
 {
 }
+
+/**
+ * @phpstan-template T
+ * @phpstan-type T never
+ */
+class Generic
+{
+}