Use non-strict type checking for built-in function callables

Built-in PHP functions always perform implicit type coercion regardless
of declare(strict_types=1), so Stringable objects should be accepted as
string parameters even in strict mode. Instead of propagating the calling
scope's $strictTypes, detect whether the callable is a built-in function
via FunctionCallableVariant::isBuiltin() and use non-strict checking for
its parameters.

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

Author: phpstan-bot

src/Reflection/Callables/FunctionCallableVariant.php

@@ -179,4 +179,14 @@ public function getAsserts(): Assertions
 		return $this->function->getAsserts();
 	}
 
+	public function isBuiltin(): bool
+	{
+		$isBuiltin = $this->function->isBuiltin();
+		if ($isBuiltin instanceof TrinaryLogic) {
+			return $isBuiltin->yes();
+		}
+
+		return $isBuiltin;
+	}
+
 }

src/Type/CallableType.php

@@ -14,6 +14,7 @@
 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;
@@ -139,7 +140,7 @@ public function accepts(Type $type, bool $strictTypes): AcceptsResult
 			return $type->isAcceptedBy($this, $strictTypes);
 		}
 
-		return $this->isSuperTypeOfInternal($type, true, $strictTypes)->toAcceptsResult();
+		return $this->isSuperTypeOfInternal($type, true)->toAcceptsResult();
 	}
 
 	public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
@@ -148,10 +149,10 @@ public function isSuperTypeOf(Type $type): IsSuperTypeOfResult
 			return $type->isSubTypeOf($this);
 		}
 
-		return $this->isSuperTypeOfInternal($type, false, true);
+		return $this->isSuperTypeOfInternal($type, false);
 	}
 
-	private function isSuperTypeOfInternal(Type $type, bool $treatMixedAsAny, bool $strictTypes): IsSuperTypeOfResult
+	private function isSuperTypeOfInternal(Type $type, bool $treatMixedAsAny): IsSuperTypeOfResult
 	{
 		$isCallable = new IsSuperTypeOfResult($type->isCallable(), []);
 		if ($isCallable->no()) {
@@ -180,11 +181,12 @@ private function isSuperTypeOfInternal(Type $type, bool $treatMixedAsAny, bool $
 
 		$variantsResult = null;
 		foreach ($type->getCallableParametersAcceptors($scope) as $variant) {
+			$isBuiltinCallable = $variant instanceof FunctionCallableVariant && $variant->isBuiltin();
 			$variant = ParametersAcceptorSelector::selectFromTypes($parameterTypes, [$variant], false);
 			if (!$variant instanceof CallableParametersAcceptor) {
 				return IsSuperTypeOfResult::createNo([]);
 			}
-			$isSuperType = CallableTypeHelper::isParametersAcceptorSuperTypeOf($this, $variant, $treatMixedAsAny, $strictTypes);
+			$isSuperType = CallableTypeHelper::isParametersAcceptorSuperTypeOf($this, $variant, $treatMixedAsAny, !$isBuiltinCallable);
 			if ($variantsResult === null) {
 				$variantsResult = $isSuperType;
 			} else {

tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php

@@ -2750,16 +2750,7 @@ public function testBug11619(): void
 	#[RequiresPhp('>= 8.1')]
 	public function testBug11619Strict(): void
 	{
-		$this->analyse([__DIR__ . '/data/bug-11619-strict.php'], [
-			[
-				'Parameter #2 $callback of function uasort expects callable(Bug11619Strict\Foo, Bug11619Strict\Foo): int, \'strnatcasecmp\' given.',
-				28,
-			],
-			[
-				'Parameter #2 $callback of function usort expects callable(Bug11619Strict\Foo, Bug11619Strict\Foo): int, \'strnatcasecmp\' given.',
-				29,
-			],
-		]);
+		$this->analyse([__DIR__ . '/data/bug-11619-strict.php'], []);
 	}
 
 	public function testBug13247(): void