[TypeDeclaration] Skip void type for arrow funtcions (#649)

rules-tests/TypeDeclaration/Rector/ClassMethod/ReturnTypeFromStrictTypedCallRector/Fixture/skip_arrow_function_void.php.inc

@@ -0,0 +1,13 @@
+<?php
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\ReturnTypeFromStrictTypedCallRector\Fixture;
+
+use Rector\Tests\TypeDeclaration\Rector\ClassMethod\ReturnTypeFromStrictTypedCallRector\Source\CallWithVoid;
+
+final class SkipArrowFunctionVoid
+{
+    public function run(CallWithVoid $callWithVoid)
+    {
+        fn() => $callWithVoid->nothing();
+    }
+}

rules-tests/TypeDeclaration/Rector/ClassMethod/ReturnTypeFromStrictTypedCallRector/Source/CallWithVoid.php

@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Tests\TypeDeclaration\Rector\ClassMethod\ReturnTypeFromStrictTypedCallRector\Source;
+
+final class CallWithVoid
+{
+    public function nothing(): void
+    {
+    }
+}

rules/TypeDeclaration/Rector/ClassMethod/ReturnTypeFromStrictTypedCallRector.php

@@ -143,6 +143,12 @@ public function refactor(Node $node): ?Node
     private function processArrowFunction(ArrowFunction $arrowFunction): ?ArrowFunction
     {
         $resolvedType = $this->nodeTypeResolver->resolve($arrowFunction->expr);
+
+        // void type is not accepted for arrow functions - https://www.php.net/manual/en/functions.arrow.php#125673
+        if ($resolvedType instanceof VoidType) {
+            return null;
+        }
+
         $returnType = $this->staticTypeMapper->mapPHPStanTypeToPhpParserNode($resolvedType, TypeKind::RETURN());
 
         if (! $returnType instanceof Node) {