[CodeQuality] Transform type|void docblock to type|null as well on Ex…

…plicitReturnNullRector after add return null (#5756)

* [CodeQuality] Transform type|void docblock to type|null on ExplicitReturnNullRector

* [CodeQuality] Transform type|void docblock to type|null on ExplicitReturnNullRector

* doc include docblock feature

* doc include docblock feature

build/target-repository/docs/rector_rules_overview.md

@@ -558,6 +558,10 @@ Add explicit return null to method/function that returns a value, but missed mai
 ```diff
  class SomeClass
  {
+     /**
+-     * @return string|void
++     * @return string|null
+      */
      public function run(int $number)
      {
          if ($number > 50) {

rules-tests/CodeQuality/Rector/ClassMethod/ExplicitReturnNullRector/Fixture/with_union_void_doc.php.inc

@@ -0,0 +1,38 @@
+<?php
+
+namespace Rector\Tests\CodeQuality\Rector\ClassMethod\ExplicitReturnNullRector\Fixture;
+
+class WithUnionVoidDoc
+{
+    /**
+     * @return string|void
+     */
+    public function run(int $number)
+    {
+        if ($number > 50) {
+            return 'yes';
+        }
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\CodeQuality\Rector\ClassMethod\ExplicitReturnNullRector\Fixture;
+
+class WithUnionVoidDoc
+{
+    /**
+     * @return string|null
+     */
+    public function run(int $number)
+    {
+        if ($number > 50) {
+            return 'yes';
+        }
+        return null;
+    }
+}
+
+?>

rules/CodeQuality/Rector/ClassMethod/ExplicitReturnNullRector.php

@@ -12,6 +12,12 @@
 use PhpParser\Node\Stmt\ClassMethod;
 use PhpParser\Node\Stmt\Return_;
 use PhpParser\Node\Stmt\Throw_;
+use PHPStan\Type\NullType;
+use PHPStan\Type\UnionType;
+use PHPStan\Type\VoidType;
+use Rector\BetterPhpDocParser\PhpDocInfo\PhpDocInfoFactory;
+use Rector\BetterPhpDocParser\PhpDocManipulator\PhpDocTypeChanger;
+use Rector\NodeTypeResolver\PHPStan\Type\TypeFactory;
 use Rector\PhpParser\Node\BetterNodeFinder;
 use Rector\Rector\AbstractRector;
 use Rector\TypeDeclaration\TypeInferer\SilentVoidResolver;
@@ -25,7 +31,10 @@ final class ExplicitReturnNullRector extends AbstractRector
 {
     public function __construct(
         private readonly BetterNodeFinder $betterNodeFinder,
-        private readonly SilentVoidResolver $silentVoidResolver
+        private readonly SilentVoidResolver $silentVoidResolver,
+        private readonly PhpDocInfoFactory $phpDocInfoFactory,
+        private readonly TypeFactory $typeFactory,
+        private readonly PhpDocTypeChanger $phpDocTypeChanger
     ) {
     }
 
@@ -38,6 +47,9 @@ public function getRuleDefinition(): RuleDefinition
                     <<<'CODE_SAMPLE'
 class SomeClass
 {
+    /**
+     * @return string|void
+     */
     public function run(int $number)
     {
         if ($number > 50) {
@@ -51,6 +63,9 @@ public function run(int $number)
                     <<<'CODE_SAMPLE'
 class SomeClass
 {
+    /**
+     * @return string|null
+     */
     public function run(int $number)
     {
         if ($number > 50) {
@@ -100,9 +115,37 @@ public function refactor(Node $node): ?Node
 
         $node->stmts[] = new Return_(new ConstFetch(new Name('null')));
 
+        $this->transformDocUnionVoidToUnionNull($node);
+
         return $node;
     }
 
+    private function transformDocUnionVoidToUnionNull(ClassMethod $classMethod): void
+    {
+        $phpDocInfo = $this->phpDocInfoFactory->createFromNodeOrEmpty($classMethod);
+
+        $returnType = $phpDocInfo->getReturnType();
+        if (! $returnType instanceof UnionType) {
+            return;
+        }
+
+        $newTypes = [];
+        foreach ($returnType->getTypes() as $type) {
+            if ($type instanceof VoidType) {
+                $type = new NullType();
+            }
+
+            $newTypes[] = $type;
+        }
+
+        $type = $this->typeFactory->createMixedPassedOrUnionTypeAndKeepConstant($newTypes);
+        if (! $type instanceof UnionType) {
+            return;
+        }
+
+        $this->phpDocTypeChanger->changeReturnType($classMethod, $phpDocInfo, $type);
+    }
+
     private function containsYieldOrThrow(ClassMethod $classMethod): bool
     {
         return (bool) $this->betterNodeFinder->findInstancesOf(