Do not transform $this in return type even in final classes

Author: calebdw

.github/workflows/e2e-tests.yml

@@ -255,6 +255,10 @@ jobs:
               echo "$OUTPUT"
               ../bashunit -a contains 'Child process error (exit code 255): PHP Fatal error' "$OUTPUT"
               ../bashunit -a contains 'Result is incomplete because of severe errors.' "$OUTPUT"
+          - script: |
+              cd e2e/bug-11857
+              composer install
+              ../../bin/phpstan
 
     steps:
       - name: "Checkout"

e2e/bug-11857/.gitignore

@@ -0,0 +1 @@
+/vendor

e2e/bug-11857/composer.json

@@ -0,0 +1,5 @@
+{
+	"autoload-dev": {
+		"classmap": ["src/"]
+	}
+}

e2e/bug-11857/composer.lock

@@ -0,0 +1,10 @@
+parameters:
+	level: 8
+	paths:
+		- src
+
+services:
+	-
+		class: Bug11857\RelationDynamicMethodReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicMethodReturnTypeExtension

e2e/bug-11857/phpstan.neon

@@ -0,0 +1,36 @@
+<?php
+
+namespace Bug11857;
+
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\MethodReflection;
+use PHPStan\Type\DynamicMethodReturnTypeExtension;
+use PHPStan\Type\Generic\GenericObjectType;
+use PHPStan\Type\ObjectType;
+use PHPStan\Type\Type;
+use PhpParser\Node\Expr\MethodCall;
+
+class RelationDynamicMethodReturnTypeExtension implements DynamicMethodReturnTypeExtension
+{
+	public function getClass(): string
+	{
+		return Model::class;
+	}
+
+	public function isMethodSupported(MethodReflection $methodReflection): bool
+	{
+		return $methodReflection->getName() === 'belongsTo';
+	}
+
+	public function getTypeFromMethodCall(MethodReflection $methodReflection, MethodCall $methodCall, Scope $scope): Type {
+		$returnType = $methodReflection->getVariants()[0]->getReturnType();
+		$argType    = $scope->getType($methodCall->getArgs()[0]->value);
+		$modelClass = $argType->getClassStringObjectType()->getObjectClassNames()[0];
+
+		return new GenericObjectType($returnType->getObjectClassNames()[0], [
+			new ObjectType($modelClass),
+			$scope->getType($methodCall->var),
+		]);
+	}
+}
+

e2e/bug-11857/src/extension.php

@@ -0,0 +1,70 @@
+<?php
+
+namespace Bug11857;
+
+use function PHPStan\Testing\assertType;
+
+abstract class Model
+{
+	/** @return BelongsTo<*, *> */
+	public function belongsTo(string $related): BelongsTo
+	{
+		return new BelongsTo();
+	}
+}
+
+/**
+ * @template TRelatedModel of Model
+ * @template TDeclaringModel of Model
+ */
+class BelongsTo {}
+
+class User extends Model {}
+
+class Post extends Model
+{
+	/** @return BelongsTo<User, $this> */
+	public function user(): BelongsTo
+	{
+		return $this->belongsTo(User::class);
+	}
+
+	/** @return BelongsTo<User, self> */
+	public function userSelf(): BelongsTo
+	{
+		/** @phpstan-ignore return.type */
+		return $this->belongsTo(User::class);
+	}
+}
+
+class ChildPost extends Post {}
+
+final class Comment extends Model
+{
+	// This model is final, so either of these
+	// two methods would work. It seems that
+	// PHPStan is automatically converting the
+	// `$this` to a `self` type in the user docblock,
+	// but it is not doing so likewise for the `$this`
+	// that is returned by the dynamic return extension.
+
+	/** @return BelongsTo<User, $this> */
+	public function user(): BelongsTo
+	{
+		return $this->belongsTo(User::class);
+	}
+
+	/** @return BelongsTo<User, self> */
+	public function user2(): BelongsTo
+	{
+		/** @phpstan-ignore return.type */
+		return $this->belongsTo(User::class);
+	}
+}
+
+function test(ChildPost $child): void
+{
+	assertType('Bug11857\BelongsTo<Bug11857\User, Bug11857\ChildPost>', $child->user());
+	// This demonstrates why `$this` is needed in non-final models
+	assertType('Bug11857\BelongsTo<Bug11857\User, Bug11857\Post>', $child->userSelf()); // should be: Bug11857\BelongsTo<Bug11857\User, Bug11857\ChildPost>
+}

e2e/bug-11857/src/test.php

@@ -3015,7 +3015,7 @@ private function transformStaticType(Type $type): Type
 			if ($type instanceof StaticType) {
 				$classReflection = $this->getClassReflection();
 				$changedType = $type->changeBaseClass($classReflection);
-				if ($classReflection->isFinal()) {
+				if ($classReflection->isFinal() && !$type instanceof ThisType) {
 					$changedType = $changedType->getStaticObjectType();
 				}
 				return $traverse($changedType);

src/Analyser/MutatingScope.php

@@ -6159,7 +6159,7 @@ private function transformStaticType(ClassReflection $declaringClass, Type $type
 		return TypeTraverser::map($type, static function (Type $type, callable $traverse) use ($declaringClass): Type {
 			if ($type instanceof StaticType) {
 				$changedType = $type->changeBaseClass($declaringClass);
-				if ($declaringClass->isFinal()) {
+				if ($declaringClass->isFinal() && !$type instanceof ThisType) {
 					$changedType = $changedType->getStaticObjectType();
 				}
 				return $traverse($changedType);

src/Analyser/NodeScopeResolver.php

@@ -299,7 +299,7 @@ private function transformStaticType(Type $type, ClassMemberAccessAnswerer $scop
 					$isFinal = $classReflection->isFinal();
 				}
 				$type = $type->changeBaseClass($classReflection);
-				if (!$isFinal) {
+				if (!$isFinal || $type instanceof ThisType) {
 					return $type;
 				}
 

src/Type/StaticType.php

@@ -1059,4 +1059,9 @@ public function testBug11663(): void
 		$this->analyse([__DIR__ . '/data/bug-11663.php'], []);
 	}
 
+	public function testBug11857(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-11857-builder.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php

@@ -0,0 +1,49 @@
+<?php // lint >= 8.0
+
+namespace Bug11857Builder;
+
+class Foo
+{
+
+	/**
+	 * @param array<string, mixed> $attributes
+	 * @return $this
+	 */
+	public function filter(array $attributes): static
+	{
+		return $this;
+	}
+
+	/**
+	 * @param array<string, mixed> $attributes
+	 * @return $this
+	 */
+	public function filterUsingRequest(array $attributes): static
+	{
+		return $this->filter($attributes);
+	}
+
+}
+
+final class FinalFoo
+{
+
+	/**
+	 * @param array<string, mixed> $attributes
+	 * @return $this
+	 */
+	public function filter(array $attributes): static
+	{
+		return $this;
+	}
+
+	/**
+	 * @param array<string, mixed> $attributes
+	 * @return $this
+	 */
+	public function filterUsingRequest(array $attributes): static
+	{
+		return $this->filter($attributes);
+	}
+
+}