🐛 Narrow only by existing return types (#903)

* 🐛 Narrow only by existing return types

Fixes a bug with #900 reported in https://www.drupal.org/project/experience_builder/issues/3539676 by @larowlan

* also test int

Author: dpi

src/Type/EntityIdNarrowedByNew.php

@@ -8,11 +8,8 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\MethodReflection;
 use PHPStan\Type\DynamicMethodReturnTypeExtension;
-use PHPStan\Type\IntegerType;
 use PHPStan\Type\NullType;
-use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
-use PHPStan\Type\TypeCombinator;
 
 /**
  * @author Daniel Phin <[email protected]>
@@ -35,15 +32,15 @@ public function getTypeFromMethodCall(
         MethodCall $methodCall,
         Scope $scope
     ): ?Type {
+        // Usually contains a UnionType with IntegerType, StringType, NullType,
+        // unless it was narrowed by a child.
+        $originalReturnType = $methodReflection->getVariants()[0]->getReturnType();
         $isNewMethodCall = new MethodCall($methodCall->var, new Identifier('isNew'));
         if ($scope->getType($isNewMethodCall)->isFalse()->yes()) {
-            return TypeCombinator::union(new IntegerType(), new StringType());
+            // Remove NULL.
+            return $originalReturnType->tryRemove(new NullType());
         }
 
-        return TypeCombinator::union(
-            new IntegerType(),
-            new StringType(),
-            new NullType()
-        );
+        return $originalReturnType;
     }
 }

tests/src/Type/data/entity.php

@@ -28,3 +28,22 @@
 assert($id3 instanceof NodeInterface);
 assert($id3->isNew() === FALSE);
 assertType('int|string', $id3->id());
+
+final class NarrowingIdString extends NodeInterface {
+    public function id(): ?string {}
+}
+assert($idNarrowedString1 instanceof NarrowingIdString);
+assertType('string|null', $idNarrowedString1->id());
+assert($idNarrowedString2 instanceof NarrowingIdString);
+assert($idNarrowedString2->isNew() === FALSE);
+assertType('string', $idNarrowedString2->id());
+
+final class NarrowingIdInt extends NodeInterface {
+    public function id(): ?int {}
+}
+assert($idNarrowedInt1 instanceof NarrowingIdInt);
+assertType('int|null', $idNarrowedInt1->id());
+assert($idNarrowedInt2 instanceof NarrowingIdInt);
+assert($idNarrowedInt2->isNew() === FALSE);
+assertType('int', $idNarrowedInt2->id());
+