[TypeDeclaration] Skip nullable self referencing param and return on AddArrayParamDocTypeRector and ReturnTypeDeclarationRector (#1183)

* Adding tests based on examples

Demo examples:
- https://getrector.org/demo/1ec3fe09-f75d-6f66-8b0b-73ca8e804aa7
- https://getrector.org/demo/1ec3fe0a-4d37-63f6-a486-899a21bb210b

* handle MixedType

* phpstan

* fix subtype in union

* fix FuncCall node name

* fix serliaze on MixedType hashing

Co-authored-by: Marco Lipparini <developer@liarco.net>
Co-authored-by: Tomas Votruba <tomas.vot@gmail.com>

packages/NodeTypeResolver/NodeTypeResolver.php

@@ -15,6 +15,7 @@ use PhpParser\Node\Expr\StaticCall;
 use PhpParser\Node\Expr\Ternary;
 use PhpParser\Node\Identifier;
 use PhpParser\Node\Name;
+use PhpParser\Node\NullableType;
 use PhpParser\Node\Param;
 use PhpParser\Node\Scalar;
 use PhpParser\Node\Stmt\Class_;
@@ -139,6 +140,13 @@ final class NodeTypeResolver
 
     public function getType(Node $node): Type
     {
+        if ($node instanceof NullableType) {
+            $type = $this->getType($node->type);
+            if (! $type instanceof MixedType) {
+                return new UnionType([$type, new NullType()]);
+            }
+        }
+
         if ($node instanceof Ternary) {
             $ternaryType = $this->resolveTernaryType($node);
             if (! $ternaryType instanceof MixedType) {

packages/NodeTypeResolver/PHPStan/TypeHasher.php

@@ -30,7 +30,7 @@ final class TypeHasher
     public function createTypeHash(Type $type): string
     {
         if ($type instanceof MixedType) {
-            return serialize($type) . $type->isExplicitMixed();
+            return $type->describe(VerbosityLevel::precise()) . $type->isExplicitMixed();
         }
 
         if ($type instanceof ArrayType) {

rules-tests/TypeDeclaration/Rector/ClassMethod/AddArrayParamDocTypeRector/Fixture/skip_nullable_self_referencing_property_setter.php.inc

@@ -0,0 +1,16 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\AddArrayParamDocTypeRector\Fixture;
+
+class SkipNullableSelfReferencingPropertySetter
+{
+    private ?self $parent = null;
+
+    public function setParent(?self $parent): self
+    {
+        $this->parent = $parent;
+
+        return $this;
+    }
+}
+?>

rules-tests/TypeDeclaration/Rector/FunctionLike/ReturnTypeDeclarationRector/Fixture/skip_nullable_self_referencing_property_getter.php.inc

@@ -0,0 +1,14 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\FunctionLike\ReturnTypeDeclarationRector\Fixture;
+
+class SkipNullableSelfReferencingPropertyGetter
+{
+    private ?self $parent = null;
+
+    public function getParent(): ?self
+    {
+        return $this->parent;
+    }
+}
+?>

rules/DowngradePhp56/Rector/Pow/DowngradeExponentialAssignmentOperatorRector.php

@@ -39,8 +39,8 @@ final class DowngradeExponentialAssignmentOperatorRector extends AbstractRector
      */
     public function refactor(Node $node): Assign
     {
-        $powCall = $this->nodeFactory->createFuncCall('pow', [$node->var, $node->expr]);
+        $powFuncCall = $this->nodeFactory->createFuncCall('pow', [$node->var, $node->expr]);
 
-        return new Assign($node->var, $powCall);
+        return new Assign($node->var, $powFuncCall);
     }
 }

rules/TypeDeclaration/Rector/FunctionLike/ReturnTypeDeclarationRector.php

@@ -220,6 +220,12 @@ CODE_SAMPLE
             return false;
         }
 
+        // probably more/less strict union type on purpose
+        if ($currentType->isSubTypeOf($inferedType)
+            ->yes()) {
+            return true;
+        }
+
         return $inferedType->isSubTypeOf($currentType)
             ->yes();
     }