Fix get_class($this) losing static type information

- StaticType::getClassStringType() was delegating to getStaticObjectType() which
  returned the base ObjectType, losing the static/this type information
- Changed it to return GenericClassStringType($this) directly, preserving the
  static type so get_class($this) correctly returns class-string<static(T)>
- This fixes false positives when passing get_class($this) to template methods
  expecting class-string<T> and returning T, where the return should be static
- New regression test in tests/PHPStan/Analyser/nsrt/bug-4860.php
- Updated existing test expectations to reflect the more precise type

Author: github-actions[bot]

src/Type/StaticType.php

@@ -16,6 +16,7 @@
 use PHPStan\Reflection\Type\UnresolvedPropertyPrototypeReflection;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Enum\EnumCaseObjectType;
+use PHPStan\Type\Generic\GenericClassStringType;
 use PHPStan\Type\Generic\GenericObjectType;
 use PHPStan\Type\Generic\TemplateTypeHelper;
 use PHPStan\Type\Traits\NonGeneralizableTypeTrait;
@@ -200,7 +201,7 @@ public function isObject(): TrinaryLogic
 
 	public function getClassStringType(): Type
 	{
-		return $this->getStaticObjectType()->getClassStringType();
+		return new GenericClassStringType($this);
 	}
 
 	public function isEnum(): TrinaryLogic

tests/PHPStan/Analyser/data/bug-7391b.php

@@ -16,7 +16,7 @@ public static function m() {
 		assertType('Bug7391B\Foo', (self::class)::m());
 		assertType('static(Bug7391B\Foo)', (static::class)::m());
 		assertType('Bug7391B\Foo', get_class(new self(2))::m());
-		assertType('Bug7391B\Foo', get_class(new static(2))::m());
+		assertType('static(Bug7391B\Foo)', get_class(new static(2))::m());
 
 		throw new \Error('For static analysis only, return type is resolved purely by DynamicStaticMethodReturnTypeExtension');
 	}

tests/PHPStan/Analyser/nsrt/bug-4860.php

@@ -0,0 +1,25 @@
+<?php declare(strict_types = 1);
+
+namespace Bug4860;
+
+use function PHPStan\Testing\assertType;
+
+class Test
+{
+	public function copy(): static
+	{
+		assertType('class-string<$this(Bug4860\Test)>', get_class($this));
+		return $this->copyTo(get_class($this));
+	}
+
+	/**
+	 * @template T
+	 * @param class-string<T> $targetEntity
+	 * @return T
+	 */
+	public function copyTo(string $targetEntity)
+	{
+		/** @var T */
+		return new $targetEntity();
+	}
+}

tests/PHPStan/Analyser/nsrt/get-parent-class.php

@@ -11,7 +11,7 @@ public function doFoo()
 	{
 		assertType('false', get_parent_class());
 		assertType('false', get_parent_class($this));
-		assertType('class-string<ParentClass\Foo>', get_class($this));
+		assertType('class-string<$this(ParentClass\Foo)>', get_class($this));
 		assertType('\'ParentClass\\\\Foo\'', get_class());
 	}
 

tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php

@@ -566,7 +566,7 @@ public function testBug3633(): void
 		$tipText = 'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.';
 		$this->analyse([__DIR__ . '/data/bug-3633.php'], [
 			[
-				'Strict comparison using === between class-string<Bug3633\HelloWorld> and \'Bug3633\\\OtherClass\' will always evaluate to false.',
+				'Strict comparison using === between class-string<$this(Bug3633\HelloWorld)> and \'Bug3633\\\OtherClass\' will always evaluate to false.',
 				37,
 				$tipText,
 			],
@@ -580,7 +580,7 @@ public function testBug3633(): void
 				44,
 			],
 			[
-				'Strict comparison using === between class-string<Bug3633\OtherClass> and \'Bug3633\\\HelloWorld\' will always evaluate to false.',
+				'Strict comparison using === between class-string<$this(Bug3633\OtherClass)> and \'Bug3633\\\HelloWorld\' will always evaluate to false.',
 				64,
 				$tipText,
 			],
@@ -595,12 +595,12 @@ public function testBug3633(): void
 				$tipText,
 			],
 			[
-				'Strict comparison using === between class-string<Bug3633\FinalClass> and \'Bug3633\\\HelloWorld\' will always evaluate to false.',
+				'Strict comparison using === between class-string<$this(Bug3633\FinalClass)> and \'Bug3633\\\HelloWorld\' will always evaluate to false.',
 				93,
 				$tipText,
 			],
 			[
-				'Strict comparison using === between class-string<Bug3633\FinalClass> and \'Bug3633\\\OtherClass\' will always evaluate to false.',
+				'Strict comparison using === between class-string<$this(Bug3633\FinalClass)> and \'Bug3633\\\OtherClass\' will always evaluate to false.',
 				96,
 				$tipText,
 			],