Revert "Fixed '$this instanceof X will always be false' in traits"

Closes phpstan/phpstan#8879
Closes phpstan/phpstan#8888

src/Analyser/MutatingScope.php

@@ -2456,26 +2456,13 @@ public function enterTrait(ClassReflection $traitReflection): self
 		if (count($traitNameParts) > 1) {
 			$namespace = implode('\\', array_slice($traitNameParts, 0, -1));
 		}
-
-		$traitContext = $this->context->enterTrait($traitReflection);
-		$classReflection = $traitContext->getClassReflection();
-		if ($classReflection === null) {
-			throw new ShouldNotHappenException();
-		}
-
-		$thisHolder = ExpressionTypeHolder::createYes(new Variable('this'), new ThisType($classReflection, null, $traitReflection));
-		$expressionTypes = $this->expressionTypes;
-		$expressionTypes['$this'] = $thisHolder;
-		$nativeExpressionTypes = $this->nativeExpressionTypes;
-		$nativeExpressionTypes['$this'] = $thisHolder;
-
 		return $this->scopeFactory->create(
-			$traitContext,
+			$this->context->enterTrait($traitReflection),
 			$this->isDeclareStrictTypes(),
 			$this->getFunction(),
 			$namespace,
-			$expressionTypes,
-			$nativeExpressionTypes,
+			$this->expressionTypes,
+			$this->nativeExpressionTypes,
 			[],
 			$this->inClosureBindScopeClass,
 			$this->anonymousFunctionReflection,

src/Type/ObjectType.php

@@ -286,31 +286,6 @@ public function isSuperTypeOf(Type $type): TrinaryLogic
 			return self::$superTypes[$thisDescription][$description] = TrinaryLogic::createMaybe();
 		}
 
-		if ($type instanceof ThisType && $type->isInTrait()) {
-			if ($type->getSubtractedType() !== null) {
-				$isSuperType = $type->getSubtractedType()->isSuperTypeOf($this);
-				if ($isSuperType->yes()) {
-					return self::$superTypes[$thisDescription][$description] = TrinaryLogic::createNo();
-				}
-			}
-
-			if ($this->getClassReflection() === null) {
-				return self::$superTypes[$thisDescription][$description] = TrinaryLogic::createMaybe();
-			}
-
-			$thisClassReflection = $this->getClassReflection();
-			if ($thisClassReflection->isTrait()) {
-				return self::$superTypes[$thisDescription][$description] = TrinaryLogic::createNo();
-			}
-
-			$traitReflection = $type->getTraitReflection();
-			if ($thisClassReflection->isFinal() && !$thisClassReflection->hasTraitUse($traitReflection->getName())) {
-				return self::$superTypes[$thisDescription][$description] = TrinaryLogic::createNo();
-			}
-
-			return self::$superTypes[$thisDescription][$description] = TrinaryLogic::createMaybe();
-		}
-
 		$transformResult = static fn (TrinaryLogic $result) => $result;
 		if ($this->subtractedType !== null) {
 			$isSuperType = $this->subtractedType->isSuperTypeOf($type);

src/Type/ThisType.php

@@ -5,7 +5,6 @@
 use PHPStan\Reflection\ClassReflection;
 use PHPStan\Reflection\ReflectionProviderStaticAccessor;
 use PHPStan\TrinaryLogic;
-use function get_class;
 use function sprintf;
 
 /** @api */
@@ -18,70 +17,24 @@ class ThisType extends StaticType
 	public function __construct(
 		ClassReflection $classReflection,
 		?Type $subtractedType = null,
-		private ?ClassReflection $traitReflection = null,
 	)
 	{
 		parent::__construct($classReflection, $subtractedType);
 	}
 
-	public function equals(Type $type): bool
-	{
-		if (get_class($type) !== static::class) {
-			return false;
-		}
-
-		/** @var ThisType $type */
-		$type = $type;
-		$equals = $this->getStaticObjectType()->equals($type->getStaticObjectType());
-		if (!$equals) {
-			return false;
-		}
-
-		if ($this->getTraitReflection() === null) {
-			if ($type->getTraitReflection() === null) {
-				return true;
-			}
-
-			return false;
-		}
-		if ($type->getTraitReflection() === null) {
-			return false;
-		}
-
-		return $this->getTraitReflection()->getName() === $type->getTraitReflection()->getName();
-	}
-
 	public function changeBaseClass(ClassReflection $classReflection): StaticType
 	{
-		return new self($classReflection, $this->getSubtractedType(), $this->traitReflection);
+		return new self($classReflection, $this->getSubtractedType());
 	}
 
 	public function describe(VerbosityLevel $level): string
 	{
-		$callback = fn () => sprintf('$this(%s)', $this->getStaticObjectType()->describe($level));
-		return $level->handle(
-			$callback,
-			$callback,
-			$callback,
-			function () use ($callback): string {
-				$base = $callback();
-				$trait = $this->getTraitReflection();
-				if ($trait === null) {
-					return $base;
-				}
-
-				return sprintf('%s-trait-%s', $base, $trait->getDisplayName());
-			},
-		);
+		return sprintf('$this(%s)', $this->getStaticObjectType()->describe($level));
 	}
 
 	public function isSuperTypeOf(Type $type): TrinaryLogic
 	{
 		if ($type instanceof self) {
-			if ($this->equals($type)) {
-				return TrinaryLogic::createYes();
-			}
-
 			return $this->getStaticObjectType()->isSuperTypeOf($type);
 		}
 
@@ -98,25 +51,12 @@ public function changeSubtractedType(?Type $subtractedType): Type
 	{
 		$type = parent::changeSubtractedType($subtractedType);
 		if ($type instanceof parent) {
-			return new self($type->getClassReflection(), $subtractedType, $this->traitReflection);
+			return new self($type->getClassReflection(), $subtractedType);
 		}
 
 		return $type;
 	}
 
-	/**
-	 * @phpstan-assert-if-true !null $this->getTraitReflection()
-	 */
-	public function isInTrait(): bool
-	{
-		return $this->traitReflection !== null;
-	}
-
-	public function getTraitReflection(): ?ClassReflection
-	{
-		return $this->traitReflection;
-	}
-
 	public function traverse(callable $cb): Type
 	{
 		$subtractedType = $this->getSubtractedType() !== null ? $cb($this->getSubtractedType()) : null;
@@ -125,7 +65,6 @@ public function traverse(callable $cb): Type
 			return new self(
 				$this->getClassReflection(),
 				$subtractedType,
-				$this->traitReflection,
 			);
 		}
 

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1179,7 +1179,6 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/callsite-cast-narrowing.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-8775.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-8752.php');
-		yield from $this->gatherAssertTypes(__DIR__ . '/data/trait-instance-of.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/list-shapes.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7607.php');
 	}

tests/PHPStan/Rules/Classes/ExistingClassInInstanceOfRuleTest.php

@@ -70,14 +70,4 @@ public function testBug7720(): void
 		]);
 	}
 
-	public function testTraitInstanceOf(): void
-	{
-		$this->analyse([__DIR__ . '/../../Analyser/data/trait-instance-of.php'], [
-			[
-				'Instanceof between $this(TraitInstanceOf\ATrait1Class) and trait TraitInstanceOf\Trait2 will always evaluate to false.',
-				21,
-			],
-		]);
-	}
-
 }

tests/PHPStan/Rules/Classes/ImpossibleInstanceOfRuleTest.php

@@ -368,11 +368,4 @@ public function testBug5333(): void
 		]);
 	}
 
-	public function testBug3632(): void
-	{
-		$this->checkAlwaysTrueInstanceOf = true;
-		$this->treatPhpDocTypesAsCertain = false;
-		$this->analyse([__DIR__ . '/data/bug-3632.php'], []);
-	}
-
 }

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -2781,4 +2781,13 @@ public function testCannotCallOnGenericClassString(): void
 		]);
 	}
 
+	public function testBug8888(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-8888.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php

@@ -820,4 +820,9 @@ public function testBug8573(): void
 		$this->analyse([__DIR__ . '/data/bug-8573.php'], []);
 	}
 
+	public function testBug8879(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-8879.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-8879.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace Bug8879;
+
+trait GetThisTrait {
+	/** @return $this */
+	function getThis() {
+		return $this;
+	}
+}
+
+/** @template T */
+final class A {
+	use GetThisTrait;
+}