now looking up the hierachy chain

fixtures/completion/this_return_value.php

@@ -1,10 +1,14 @@
 <?php
-class Parent1 {
+class Grand
+{
   /** @return $this */
   public function foo() {
     return $this;
   }
 }
+class Parent1 extends Grand {
+  
+}
 
 class Child extends Parent1 {
   public function bar() {

src/DefinitionResolver.php

@@ -670,16 +670,19 @@ class DefinitionResolver
                 if ($expr->parent instanceof Node\Expression\CallExpression) {
                     $add .= '()';
                 }
-                $fqn = $classFqn . $add;
+                $lookupDefinition = function (string $base, string $add) use (&$lookupDefinition) {
-                $def = $this->index->getDefinition($fqn);
+                    $def = $this->index->getDefinition($base . $add);
-                if ($def !== null) {
-                    return $def->type;
-                } else {
-                    $classDef = $this->index->getDefinition($classFqn);
-                    if ($classDef !== null && is_array($classDef->extends)) {
-                        foreach ($classDef->extends as $parent) {
-                            $def = $this->index->getDefinition($parent . $add);
                     if ($def !== null) {
+                        yield $def;
+                    }
+                    $baseDef = $this->index->getDefinition($base);
+                    if ($baseDef !== null && is_array($baseDef->extends)) {
+                        foreach ($baseDef->extends as $name) {
+                            yield from $lookupDefinition($name, $add);
+                        }
+                    }
+                };
+                foreach ($lookupDefinition($classFqn, $add) as $def) {
                     if ($def->type instanceof Types\This) {
                         return new Types\Object_(new Fqsen('\\' . $classFqn));
                     }
@@ -687,9 +690,6 @@ class DefinitionResolver
                 }
             }
         }
-                }
-            }
-        }
 
         // SCOPED PROPERTY ACCESS EXPRESSION
         if ($expr instanceof Node\Expression\ScopedPropertyAccessExpression) {

tests/Server/TextDocument/CompletionTest.php

@@ -660,7 +660,7 @@ class CompletionTest extends TestCase
         $this->loader->open($completionUri, file_get_contents($completionUri));
         $items = $this->textDocument->completion(
             new TextDocumentIdentifier($completionUri),
-            new Position(10, 19)
+            new Position(14, 19)
         )->wait();
         $this->assertEquals(new CompletionList([
             new CompletionItem(