Use NullishType::class and fix CS violations

- Restore NullishType::class instead of string literal
- Add baseline ignores for older PSL versions without NullishType
- Fix CS: add use statements for NullishType and class_exists in test

Author: veewee

phpstan-baseline-psl-1.neon

@@ -11,3 +11,15 @@ parameters:
 			identifier: argument.type
 			count: 1
 			path: src/Option/OptionFilterReturnTypeExtension.php
+
+		-
+			message: '#^Class Psl\\Type\\Internal\\NullishType not found\.$#'
+			identifier: class.notFound
+			count: 1
+			path: src/Type/TypeShapeReturnTypeExtension.php
+
+		-
+			message: '#^Parameter \#1 \$ancestorClassName of method PHPStan\\Type\\Type\:\:getTemplateType\(\) expects class\-string, string given\.$#'
+			identifier: argument.type
+			count: 1
+			path: src/Type/TypeShapeReturnTypeExtension.php

src/Type/TypeShapeReturnTypeExtension.php

@@ -12,6 +12,7 @@
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
+use Psl\Type\Internal\NullishType;
 use Psl\Type\Internal\OptionalType;
 use Psl\Type\TypeInterface;
 use function count;
@@ -70,7 +71,7 @@ private function createResult(ConstantArrayType $arrayType): Type
 	 */
 	private function extractNullish(Type $type): array
 	{
-		$nullishType = $type->getTemplateType('Psl\Type\Internal\NullishType', 'T');
+		$nullishType = $type->getTemplateType(NullishType::class, 'T');
 		if ($nullishType instanceof ErrorType) {
 			return [$type, false];
 		}

tests/Type/PslTypeSpecifyingExtensionTest.php

@@ -5,6 +5,8 @@
 use Composer\InstalledVersions;
 use Composer\Semver\VersionParser;
 use PHPStan\Testing\TypeInferenceTestCase;
+use Psl\Type\Internal\NullishType;
+use function class_exists;
 
 class PslTypeSpecifyingExtensionTest extends TypeInferenceTestCase
 {
@@ -17,7 +19,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/coerce.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/assert.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/matches.php');
-		if (class_exists(\Psl\Type\Internal\NullishType::class)) {
+		if (class_exists(NullishType::class)) {
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/nullishCoerce.php');
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/nullishAssert.php');
 			yield from $this->gatherAssertTypes(__DIR__ . '/data/nullishMatches.php');