From d13e0fa8585922b25deffff46f143c8dc1dd3d43 Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Thu, 13 Aug 2026 18:00:44 +0200
Subject: [PATCH] Derive the type-check verdict in FuncCallHandler

TypeSpecifyingFunctionsDynamicReturnTypeExtension existed only to pin
array_key_exists()/key_exists()/in_array()/is_subclass_of() calls to
ConstantBooleanType when the check is decided - and it needed the
TypeSpecifierAwareExtension setter dance to construct
ImpossibleCheckTypeHelper. The verdict now lives at the same decision
point inside FuncCallHandler's dynamic-return-type resolution, with the
helper constructor-injected; the extension is deleted.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DaBZjgksga4c5s6Q9FniY7
---
 src/Analyser/ExprHandler/FuncCallHandler.php  | 16 ++++
 ...ingFunctionsDynamicReturnTypeExtension.php | 77 -------------------
 2 files changed, 16 insertions(+), 77 deletions(-)
 delete mode 100644 src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php

diff --git a/src/Analyser/ExprHandler/FuncCallHandler.php b/src/Analyser/ExprHandler/FuncCallHandler.php
index 212d20038b1..689638715c3 100644
--- a/src/Analyser/ExprHandler/FuncCallHandler.php
+++ b/src/Analyser/ExprHandler/FuncCallHandler.php
@@ -48,6 +48,7 @@
 use PHPStan\Reflection\ParametersAcceptor;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Reflection\ReflectionProvider;
+use PHPStan\Rules\Comparison\ImpossibleCheckTypeHelper;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\HasPropertyType;
@@ -56,6 +57,7 @@
 use PHPStan\Type\ClosureType;
 use PHPStan\Type\Constant\ConstantArrayType;
 use PHPStan\Type\Constant\ConstantArrayTypeBuilder;
+use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\DynamicFunctionThrowTypeExtension;
 use PHPStan\Type\DynamicReturnTypeExtensionRegistry;
 use PHPStan\Type\ErrorType;
@@ -107,6 +109,7 @@ public function __construct(
 		#[AutowiredParameter]
 		private bool $rememberPossiblyImpureFunctionValues,
 		private ExpressionResultFactory $expressionResultFactory,
+		private ImpossibleCheckTypeHelper $impossibleCheckTypeHelper,
 	)
 	{
 	}
@@ -1053,6 +1056,19 @@ private function getDynamicFunctionReturnType(MutatingScope $scope, FuncCall $no
 			}
 		}
 
+		// for always-true/always-false type checks the call's own narrowing
+		// decides the return type - the verdict reads the same specified types
+		// the check contributes when used as a condition
+		if (
+			$normalizedNode->name instanceof Name
+			&& in_array($normalizedNode->name->toLowerString(), ['array_key_exists', 'key_exists', 'in_array', 'is_subclass_of'], true)
+		) {
+			$isAlways = $this->impossibleCheckTypeHelper->findSpecifiedType($scope, $normalizedNode);
+			if ($isAlways !== null) {
+				return new ConstantBooleanType($isAlways);
+			}
+		}
+
 		return null;
 	}
 
diff --git a/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php b/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php
deleted file mode 100644
index fdc77b5e4a5..00000000000
--- a/src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php
+++ /dev/null
@@ -1,77 +0,0 @@
-<?php declare(strict_types = 1);
-
-namespace PHPStan\Type\Php;
-
-use PhpParser\Node\Expr\FuncCall;
-use PHPStan\Analyser\Scope;
-use PHPStan\Analyser\TypeSpecifier;
-use PHPStan\Analyser\TypeSpecifierAwareExtension;
-use PHPStan\DependencyInjection\AutowiredParameter;
-use PHPStan\DependencyInjection\AutowiredService;
-use PHPStan\Reflection\FunctionReflection;
-use PHPStan\Reflection\ReflectionProvider;
-use PHPStan\Rules\Comparison\ImpossibleCheckTypeHelper;
-use PHPStan\Type\Constant\ConstantBooleanType;
-use PHPStan\Type\DynamicFunctionReturnTypeExtension;
-use PHPStan\Type\Type;
-use function count;
-use function in_array;
-
-#[AutowiredService]
-final class TypeSpecifyingFunctionsDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension, TypeSpecifierAwareExtension
-{
-
-	private TypeSpecifier $typeSpecifier;
-
-	private ?ImpossibleCheckTypeHelper $helper = null;
-
-	public function __construct(
-		private ReflectionProvider $reflectionProvider,
-		#[AutowiredParameter]
-		private bool $treatPhpDocTypesAsCertain,
-	)
-	{
-	}
-
-	public function setTypeSpecifier(TypeSpecifier $typeSpecifier): void
-	{
-		$this->typeSpecifier = $typeSpecifier;
-	}
-
-	public function isFunctionSupported(FunctionReflection $functionReflection): bool
-	{
-		return in_array($functionReflection->getName(), [
-			'array_key_exists',
-			'key_exists',
-			'in_array',
-			'is_subclass_of',
-		], true);
-	}
-
-	public function getTypeFromFunctionCall(
-		FunctionReflection $functionReflection,
-		FuncCall $functionCall,
-		Scope $scope,
-	): ?Type
-	{
-		if (count($functionCall->getArgs()) === 0) {
-			return null;
-		}
-
-		$isAlways = $this->getHelper()->findSpecifiedType(
-			$scope,
-			$functionCall,
-		);
-		if ($isAlways === null) {
-			return null;
-		}
-
-		return new ConstantBooleanType($isAlways);
-	}
-
-	private function getHelper(): ImpossibleCheckTypeHelper
-	{
-		return $this->helper ??= new ImpossibleCheckTypeHelper($this->reflectionProvider, $this->typeSpecifier, $this->treatPhpDocTypesAsCertain);
-	}
-
-}