[TypeDeclarationDocblocks] Guard DocblockVarArrayFromPropertyDefaultsRector against unsound narrowing (#8435)

Author: TomasVotruba

rules-tests/TypeDeclarationDocblocks/Rector/Class_/DocblockVarArrayFromPropertyDefaultsRector/Fixture/array_union_generic_same_type.php.inc

@@ -7,7 +7,7 @@ use stdClass;
 
 class ArrayUnionGenericSameType
 {
-    protected array $dependencies = [
+    private array $dependencies = [
         stdClass::class,
         DateTime::class,
     ];
@@ -27,7 +27,7 @@ class ArrayUnionGenericSameType
     /**
      * @var array<int, class-string<\stdClass>|class-string<\DateTime>>
      */
-    protected array $dependencies = [
+    private array $dependencies = [
         stdClass::class,
         DateTime::class,
     ];

rules-tests/TypeDeclarationDocblocks/Rector/Class_/DocblockVarArrayFromPropertyDefaultsRector/Fixture/skip_empty_nested_array.php.inc

@@ -0,0 +1,13 @@
+<?php
+
+namespace Rector\Tests\TypeDeclarationDocblocks\Rector\Class_\DocblockVarArrayFromPropertyDefaultsRector\Fixture;
+
+final class SkipEmptyNestedArray
+{
+    private array $payload = ['create' => [], 'update' => []];
+
+    public function add(string $key, array $item): void
+    {
+        $this->payload['create'][$key] = $item;
+    }
+}

rules-tests/TypeDeclarationDocblocks/Rector/Class_/DocblockVarArrayFromPropertyDefaultsRector/Fixture/skip_non_private_property.php.inc

@@ -0,0 +1,8 @@
+<?php
+
+namespace Rector\Tests\TypeDeclarationDocblocks\Rector\Class_\DocblockVarArrayFromPropertyDefaultsRector\Fixture;
+
+class SkipNonPrivateProperty
+{
+    protected array $configParams = ['enabled' => true, 'name' => 'value'];
+}

rules/TypeDeclarationDocblocks/Rector/Class_/DocblockVarArrayFromPropertyDefaultsRector.php

@@ -6,6 +6,7 @@
 
 use PhpParser\Comment\Doc;
 use PhpParser\Node;
+use PhpParser\Node\ArrayItem;
 use PhpParser\Node\Expr\Array_;
 use PhpParser\Node\Identifier;
 use PhpParser\Node\PropertyItem;
@@ -80,6 +81,11 @@ public function refactor(Node $node): ?Node
                 continue;
             }
 
+            // only private properties are safe; a protected/public one can be reassigned with a wider type by a child class we cannot see here
+            if (! $property->isPrivate()) {
+                continue;
+            }
+
             if (count($property->props) > 1) {
                 continue;
             }
@@ -89,6 +95,11 @@ public function refactor(Node $node): ?Node
                 continue;
             }
 
+            // an empty nested array default generalizes to never[], which then rejects every real value assigned later
+            if ($this->hasEmptyNestedArray($soleProperty->default)) {
+                continue;
+            }
+
             $propertyDefaultType = $this->getType($soleProperty->default);
 
             $propertyPhpDocInfo = $this->phpDocInfoFactory->createFromNodeOrEmpty($property);
@@ -118,6 +129,29 @@ public function refactor(Node $node): ?Node
         return $node;
     }
 
+    private function hasEmptyNestedArray(Array_ $array): bool
+    {
+        foreach ($array->items as $arrayItem) {
+            if (! $arrayItem instanceof ArrayItem) {
+                continue;
+            }
+
+            if (! $arrayItem->value instanceof Array_) {
+                continue;
+            }
+
+            if ($arrayItem->value->items === []) {
+                return true;
+            }
+
+            if ($this->hasEmptyNestedArray($arrayItem->value)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     private function hasUsefulParentPropertyVarTag(Class_ $class, Property $property, Type $propertyDefaultType): bool
     {
         $propertyName = $this->getName($property);