Add is_object() on DowngradeInstanceofStringableRector when possibly not object type

rules-tests/DowngradePhp80/Rector/Instanceof_/DowngradeInstanceofStringableRector/Fixture/exactly_object_type.php.inc

@@ -0,0 +1,27 @@
+<?php
+
+namespace Rector\Tests\DowngradePhp80\Rector\Instanceof_\DowngradeInstanceofStringableRector\Fixture;
+
+class ExactlyObjectType
+{
+    public function run(object $obj)
+    {
+        return $obj instanceof \Stringable;
+    }
+}
+
+?>
+-----
+<?php
+
+namespace Rector\Tests\DowngradePhp80\Rector\Instanceof_\DowngradeInstanceofStringableRector\Fixture;
+
+class ExactlyObjectType
+{
+    public function run(object $obj)
+    {
+        return method_exists($obj, '__toString');
+    }
+}
+
+?>

rules-tests/DowngradePhp80/Rector/Instanceof_/DowngradeInstanceofStringableRector/Fixture/fixture.php.inc

@@ -20,7 +20,7 @@ class Fixture
 {
     public function run($obj)
     {
-        return method_exists($obj, '__toString');
+        return is_object($obj) && method_exists($obj, '__toString');
     }
 }
 

rules/DowngradePhp80/Rector/Instanceof_/DowngradeInstanceofStringableRector.php

@@ -5,6 +5,8 @@
 namespace Rector\DowngradePhp80\Rector\Instanceof_;
 
 use PhpParser\Node;
+use PhpParser\Node\Expr\BinaryOp\BooleanAnd;
+use PhpParser\Node\Expr\FuncCall;
 use PhpParser\Node\Expr\Instanceof_;
 use PhpParser\Node\Name\FullyQualified;
 use PhpParser\Node\Scalar\String_;
@@ -28,7 +30,7 @@ public function getRuleDefinition(): RuleDefinition
 
                 ,
                 <<<'CODE_SAMPLE'
-method_exists($obj, '__toString');
+is_object($obj) && method_exists($obj, '__toString');
 CODE_SAMPLE
             ),
         ]);
@@ -45,7 +47,7 @@ public function getNodeTypes(): array
     /**
      * @param Instanceof_ $node
      */
-    public function refactor(Node $node): ?Node
+    public function refactor(Node $node): null|FuncCall|BooleanAnd
     {
         if (! $node->class instanceof FullyQualified) {
             return null;
@@ -55,6 +57,13 @@ public function refactor(Node $node): ?Node
             return null;
         }
 
-        return $this->nodeFactory->createFuncCall('method_exists', [$node->expr, new String_('__toString')]);
+        $nativeExprType = $this->nodeTypeResolver->getNativeType($node->expr);
+        $funcCall = $this->nodeFactory->createFuncCall('method_exists', [$node->expr, new String_('__toString')]);
+
+        if ($nativeExprType->isObject()->yes()) {
+            return $funcCall;
+        }
+
+        return new BooleanAnd($this->nodeFactory->createFuncCall('is_object', [$node->expr]), $funcCall);
     }
 }