Completion for inherited this

src/CompletionProvider.php

@@ -130,6 +130,10 @@ class CompletionProvider
         $list = new CompletionList;
         $list->isIncomplete = true;
 
+        //echo get_class($node->var);
+        //var_dump((string)$node->var->name);
+        //die();
+
         // A non-free node means we do NOT suggest global symbols
         if (
             $node instanceof Node\Expr\MethodCall

src/DefinitionResolver.php

@@ -479,16 +479,22 @@ class DefinitionResolver
                 } else {
                     $classFqn = substr((string)$t->getFqsen(), 1);
                 }
-                $fqn = $classFqn . '->' . $expr->name;
+                $extended = $this->expandParentFqns([$classFqn]);
+                foreach ($extended as $f) {
+                    $fqn = $f . '->' . $expr->name;
                     if ($expr instanceof Node\Expr\MethodCall) {
                         $fqn .= '()';
                     }
                     $def = $this->index->getDefinition($fqn);
                     if ($def !== null) {
+                        if ($def->type instanceof Types\This || $def->type instanceof Types\Self_) {
+                            return $this->resolveExpressionNodeToType($expr->var);
+                        }
                         return $def->type;
                     }
                 }
             }
+        }
         if (
             $expr instanceof Node\Expr\StaticCall
             || $expr instanceof Node\Expr\StaticPropertyFetch
@@ -651,6 +657,26 @@ class DefinitionResolver
         return new Types\Mixed;
     }
 
+    /**
+     * Adds the FQNs of all parent classes to an array of FQNs of classes
+     *
+     * @param string[] $fqns
+     * @return string[]
+     */
+    private function expandParentFqns(array $fqns): array
+    {
+        $expanded = $fqns;
+        foreach ($fqns as $fqn) {
+            $def = $this->index->getDefinition($fqn);
+            if ($def) {
+                foreach ($this->expandParentFqns($def->extends) as $parent) {
+                    $expanded[] = $parent;
+                }
+            }
+        }
+        return $expanded;
+    }
+
     /**
      * Takes any class name node (from a static method call, or new node) and returns a Type object
      * Resolves keywords like self, static and parent