Fix phpstan/phpstan#7088: Accessing SimpleXMLElement nodes using braces gives mixed type (#5406)

Co-authored-by: VincentLanglet <9052536+VincentLanglet@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

src/Analyser/ExprHandler/PropertyFetchHandler.php

@@ -33,6 +33,14 @@
 final class PropertyFetchHandler implements ExprHandler
 {
 
+	/**
+	 * Representative property name used when resolving dynamic property access ($obj->{$expr}).
+	 * The actual name doesn't matter — it just needs to be non-empty so that
+	 * PropertiesClassReflectionExtensions (e.g. SimpleXMLElement) that accept
+	 * any property name can return the correct type.
+	 */
+	private const DYNAMIC_PROPERTY_NAME = '__phpstan_dynamic_property';
+
 	public function __construct(
 		private PhpVersion $phpVersion,
 		private PropertyReflectionFinder $propertyReflectionFinder,
@@ -130,6 +138,14 @@ public function resolveType(MutatingScope $scope, Expr $expr): Type
 			);
 		}
 
+		if ($nameType->isString()->yes()) {
+			$fetchedOnType = $scope->getType($expr->var);
+			$returnType = $this->propertyFetchType($scope, $fetchedOnType, self::DYNAMIC_PROPERTY_NAME, $expr);
+			if ($returnType !== null) {
+				return NullsafeShortCircuitingHelper::getType($scope, $expr->var, $returnType);
+			}
+		}
+
 		return new MixedType();
 	}
 

tests/PHPStan/Analyser/nsrt/bug-7088.php

@@ -0,0 +1,15 @@
+<?php declare(strict_types = 1);
+
+namespace Bug7088;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	public function sayHello(\SimpleXMLElement $prop, string $x): void
+	{
+		assertType('(SimpleXMLElement|null)', $prop->foo);
+		assertType('(SimpleXMLElement|null)', $prop->{'foo-bar'});
+		assertType('(SimpleXMLElement|null)', $prop->{$x});
+	}
+}