Type system: ConstantStringType created from ::class is always considered a classname

Author: ondrejmirtes

src/Type/ClassStringType.php

@@ -2,7 +2,6 @@
 
 namespace PHPStan\Type;
 
-use PHPStan\Reflection\ReflectionProviderStaticAccessor;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Constant\ConstantStringType;
 
@@ -28,8 +27,7 @@ public function accepts(Type $type, bool $strictTypes): TrinaryLogic
 		}
 
 		if ($type instanceof ConstantStringType) {
-			$reflectionProvider = ReflectionProviderStaticAccessor::getInstance();
-			return TrinaryLogic::createFromBoolean($reflectionProvider->hasClass($type->getValue()));
+			return TrinaryLogic::createFromBoolean($type->isClassString());
 		}
 
 		if ($type instanceof self) {
@@ -46,8 +44,7 @@ public function accepts(Type $type, bool $strictTypes): TrinaryLogic
 	public function isSuperTypeOf(Type $type): TrinaryLogic
 	{
 		if ($type instanceof ConstantStringType) {
-			$reflectionProvider = ReflectionProviderStaticAccessor::getInstance();
-			return TrinaryLogic::createFromBoolean($reflectionProvider->hasClass($type->getValue()));
+			return TrinaryLogic::createFromBoolean($type->isClassString());
 		}
 
 		if ($type instanceof self) {

src/Type/Constant/ConstantStringType.php

@@ -57,7 +57,13 @@ public function getValue(): string
 
 	public function isClassString(): bool
 	{
-		return $this->isClassString;
+		if ($this->isClassString) {
+			return true;
+		}
+
+		$reflectionProvider = ReflectionProviderStaticAccessor::getInstance();
+
+		return $reflectionProvider->hasClass($this->value);
 	}
 
 	public function describe(VerbosityLevel $level): string
@@ -118,9 +124,7 @@ public function isSuperTypeOf(Type $type): TrinaryLogic
 			return TrinaryLogic::createNo();
 		}
 		if ($type instanceof ClassStringType) {
-			$reflectionProvider = ReflectionProviderStaticAccessor::getInstance();
-
-			return $reflectionProvider->hasClass($this->getValue()) ? TrinaryLogic::createMaybe() : TrinaryLogic::createNo();
+			return $this->isClassString() ? TrinaryLogic::createMaybe() : TrinaryLogic::createNo();
 		}
 
 		if ($type instanceof self) {

src/Type/Generic/GenericClassStringType.php

@@ -2,7 +2,6 @@
 
 namespace PHPStan\Type\Generic;
 
-use PHPStan\Reflection\ReflectionProviderStaticAccessor;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\ClassStringType;
 use PHPStan\Type\CompoundType;
@@ -53,8 +52,7 @@ public function accepts(Type $type, bool $strictTypes): TrinaryLogic
 		}
 
 		if ($type instanceof ConstantStringType) {
-			$reflectionProvider = ReflectionProviderStaticAccessor::getInstance();
-			if (!$reflectionProvider->hasClass($type->getValue())) {
+			if (!$type->isClassString()) {
 				return TrinaryLogic::createNo();
 			}
 

src/Type/Php/ClassExistsFunctionTypeSpecifyingExtension.php

@@ -16,8 +16,6 @@
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\Constant\ConstantStringType;
 use PHPStan\Type\FunctionTypeSpecifyingExtension;
-use PHPStan\Type\NeverType;
-use PHPStan\Type\TypeCombinator;
 
 class ClassExistsFunctionTypeSpecifyingExtension implements FunctionTypeSpecifyingExtension, TypeSpecifierAwareExtension
 {
@@ -41,20 +39,16 @@ public function specifyTypes(FunctionReflection $functionReflection, FuncCall $n
 	{
 		$argType = $scope->getType($node->getArgs()[0]->value);
 		$classStringType = new ClassStringType();
-		if (TypeCombinator::intersect($argType, $classStringType) instanceof NeverType) {
-			if ($argType instanceof ConstantStringType) {
-				return $this->typeSpecifier->create(
-					new FuncCall(new FullyQualified('class_exists'), [
-						new Arg(new String_(ltrim($argType->getValue(), '\\'))),
-					]),
-					new ConstantBooleanType(true),
-					$context,
-					false,
-					$scope
-				);
-			}
-
-			return new SpecifiedTypes();
+		if ($argType instanceof ConstantStringType) {
+			return $this->typeSpecifier->create(
+				new FuncCall(new FullyQualified('class_exists'), [
+					new Arg(new String_(ltrim($argType->getValue(), '\\'))),
+				]),
+				new ConstantBooleanType(true),
+				$context,
+				false,
+				$scope
+			);
 		}
 
 		return $this->typeSpecifier->create(

tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php

@@ -564,4 +564,9 @@ public function testBug5218(bool $checkExplicitMixed, array $errors): void
 		$this->analyse([__DIR__ . '/data/bug-5218.php'], $errors);
 	}
 
+	public function testBug5979(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-5979.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-5979.php

@@ -0,0 +1,31 @@
+<?php declare(strict_types = 1);
+
+namespace Bug5979;
+
+class HelloWorld
+{
+	/**
+	 * @return list<array{string, class-string}>
+	 */
+	public function dataProviderForTestValidCommands(): array
+	{
+		$data = [
+			// left out some commands here for simplicity ...
+			// [...]
+			[
+				'migrations:execute',
+				SplQueue::class,
+			],
+		];
+
+		// this is only available with DBAL 2.x
+		if (class_exists(ImportCommand::class)) {
+			$data[] = [
+				'dbal:import',
+				ImportCommand::class,
+			];
+		}
+
+		return $data;
+	}
+}