Move isBuiltin() method to CallableParametersAcceptor interface

Instead of checking `instanceof FunctionCallableVariant` in CallableType,
the isBuiltin() method is now part of the CallableParametersAcceptor
interface and implemented by all classes. The value is propagated through
ExtendedCallableFunctionVariant and ResolvedFunctionVariantWithCallable.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

src/Reflection/Callables/CallableParametersAcceptor.php

@@ -60,4 +60,6 @@ public function mustUseReturnValue(): TrinaryLogic;
 
 	public function getAsserts(): Assertions;
 
+	public function isBuiltin(): TrinaryLogic;
+
 }

src/Reflection/ExtendedCallableFunctionVariant.php

@@ -38,6 +38,7 @@ public function __construct(
 		private TrinaryLogic $acceptsNamedArguments,
 		private TrinaryLogic $mustUseReturnValue,
 		private ?Assertions $assertions = null,
+		private ?TrinaryLogic $isBuiltinCallable = null,
 	)
 	{
 		parent::__construct(
@@ -92,4 +93,9 @@ public function getAsserts(): Assertions
 		return $this->assertions ?? Assertions::createEmpty();
 	}
 
+	public function isBuiltin(): TrinaryLogic
+	{
+		return $this->isBuiltinCallable ?? TrinaryLogic::createNo();
+	}
+
 }

src/Reflection/GenericParametersAcceptorResolver.php

@@ -131,6 +131,7 @@ public static function resolve(array $argTypes, ParametersAcceptor $parametersAc
 				$originalParametersAcceptor->acceptsNamedArguments(),
 				$originalParametersAcceptor->mustUseReturnValue(),
 				$originalParametersAcceptor->getAsserts(),
+				$originalParametersAcceptor->isBuiltin(),
 			);
 		}
 

src/Reflection/InaccessibleMethod.php

@@ -98,4 +98,9 @@ public function getAsserts(): Assertions
 		return Assertions::createEmpty();
 	}
 
+	public function isBuiltin(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 }

src/Reflection/ParametersAcceptorSelector.php

@@ -736,6 +736,7 @@ public static function combineAcceptors(array $acceptors): ExtendedParametersAcc
 		$usedVariables = [];
 		$acceptsNamedArguments = TrinaryLogic::createNo();
 		$mustUseReturnValue = TrinaryLogic::createMaybe();
+		$isBuiltin = TrinaryLogic::createNo();
 
 		foreach ($acceptors as $acceptor) {
 			$returnTypes[] = $acceptor->getReturnType();
@@ -753,6 +754,7 @@ public static function combineAcceptors(array $acceptors): ExtendedParametersAcc
 				$usedVariables = array_merge($usedVariables, $acceptor->getUsedVariables());
 				$acceptsNamedArguments = $acceptsNamedArguments->or($acceptor->acceptsNamedArguments());
 				$mustUseReturnValue = $mustUseReturnValue->or($acceptor->mustUseReturnValue());
+				$isBuiltin = $isBuiltin->or($acceptor->isBuiltin());
 			}
 			$isVariadic = $isVariadic || $acceptor->isVariadic();
 
@@ -860,6 +862,7 @@ public static function combineAcceptors(array $acceptors): ExtendedParametersAcc
 				$usedVariables,
 				$acceptsNamedArguments,
 				$mustUseReturnValue,
+				isBuiltinCallable: $isBuiltin,
 			);
 		}
 
@@ -898,6 +901,7 @@ private static function wrapAcceptor(ParametersAcceptor $acceptor): ExtendedPara
 				$acceptor->acceptsNamedArguments(),
 				$acceptor->mustUseReturnValue(),
 				$acceptor->getAsserts(),
+				$acceptor->isBuiltin(),
 			);
 		}
 

src/Reflection/ResolvedFunctionVariantWithCallable.php

@@ -30,6 +30,7 @@ public function __construct(
 		private TrinaryLogic $acceptsNamedArguments,
 		private TrinaryLogic $mustUseReturnValue,
 		private ?Assertions $assertions = null,
+		private ?TrinaryLogic $isBuiltinCallable = null,
 	)
 	{
 	}
@@ -124,4 +125,9 @@ public function getAsserts(): Assertions
 		return $this->assertions ?? Assertions::createEmpty();
 	}
 
+	public function isBuiltin(): TrinaryLogic
+	{
+		return $this->isBuiltinCallable ?? TrinaryLogic::createNo();
+	}
+
 }

src/Reflection/TrivialParametersAcceptor.php

@@ -108,4 +108,9 @@ public function getAsserts(): Assertions
 		return Assertions::createEmpty();
 	}
 
+	public function isBuiltin(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 }

src/Type/CallableType.php

@@ -14,7 +14,6 @@
 use PHPStan\PhpDocParser\Printer\Printer;
 use PHPStan\Reflection\Assertions;
 use PHPStan\Reflection\Callables\CallableParametersAcceptor;
-use PHPStan\Reflection\Callables\FunctionCallableVariant;
 use PHPStan\Reflection\Callables\SimpleImpurePoint;
 use PHPStan\Reflection\Callables\SimpleThrowPoint;
 use PHPStan\Reflection\ClassMemberAccessAnswerer;
@@ -181,7 +180,7 @@ private function isSuperTypeOfInternal(Type $type, bool $treatMixedAsAny): IsSup
 
 		$variantsResult = null;
 		foreach ($type->getCallableParametersAcceptors($scope) as $variant) {
-			$isBuiltinCallable = $variant instanceof FunctionCallableVariant && $variant->isBuiltin()->yes();
+			$isBuiltinCallable = $variant->isBuiltin()->yes();
 			$variant = ParametersAcceptorSelector::selectFromTypes($parameterTypes, [$variant], false);
 			if (!$variant instanceof CallableParametersAcceptor) {
 				return IsSuperTypeOfResult::createNo([]);
@@ -406,6 +405,11 @@ public function getAsserts(): Assertions
 		return Assertions::createEmpty();
 	}
 
+	public function isBuiltin(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function toNumber(): Type
 	{
 		return new ErrorType();

src/Type/ClosureType.php

@@ -138,6 +138,11 @@ public function getAsserts(): Assertions
 		return $this->assertions;
 	}
 
+	public function isBuiltin(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	/**
 	 * @return array<non-empty-string, TemplateTag>
 	 */