[DeadCode] Keep @return union docblock when native type involves array (preserves iterable value type)

Author: TomasVotruba

rules-tests/DeadCode/Rector/ClassMethod/RemoveUselessUnionReturnDocblockRector/Fixture/skip_nullable_array_native.php.inc

@@ -0,0 +1,13 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\ClassMethod\RemoveUselessUnionReturnDocblockRector\Fixture;
+
+final class SkipNullableArrayNative
+{
+    /**
+     * @return mixed[]|null
+     */
+    public function run(): ?array
+    {
+    }
+}

rules-tests/DeadCode/Rector/ClassMethod/RemoveUselessUnionReturnDocblockRector/Fixture/skip_union_with_array_native.php.inc

@@ -0,0 +1,13 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\ClassMethod\RemoveUselessUnionReturnDocblockRector\Fixture;
+
+final class SkipUnionWithArrayNative
+{
+    /**
+     * @return string|mixed[]|int
+     */
+    public function run(): string|array|int
+    {
+    }
+}

rules/DeadCode/Rector/ClassMethod/RemoveUselessUnionReturnDocblockRector.php

@@ -106,8 +106,8 @@ public function refactor(Node $node): ?Node
 
         $nativeReturnType = $this->staticTypeMapper->mapPhpParserNodePHPStanType($node->returnType);
 
-        // keep array native type, the docblock may carry element types
-        if ($nativeReturnType->isArray()->yes()) {
+        // keep array-involving native type (array, ?array, union with array), the docblock may carry element types
+        if (! $nativeReturnType->isArray()->no()) {
             return null;
         }