Implement proper scoping for "this" in arrow functions

src/compiler/ast-graph-builder.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/ast-graph-builder.h"
 
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/linkage.h"
@@ skipping 440 matching lines @@
     // It will be replaced with {Dead} after typing and optimizations.
     NewNode(common()->OsrNormalEntry());
   }
 
   // Initialize the incoming context.
   CreateFunctionContext(constant_context);
   ContextScope incoming(this, scope, function_context_.get());
 
   // Build receiver check for sloppy mode if necessary.
   // TODO(mstarzinger/verwaest): Should this be moved back into the CallIC?
-  Node* original_receiver = env.Lookup(scope->receiver());
-  Node* patched_receiver = BuildPatchReceiverToGlobalProxy(original_receiver);
-  env.Bind(scope->receiver(), patched_receiver);
+  if (scope->has_this_declaration()) {
+    Node* original_receiver = env.Lookup(scope->receiver());
+    Node* patched_receiver = BuildPatchReceiverToGlobalProxy(original_receiver);
+    env.Bind(scope->receiver(), patched_receiver);
+  }
 
   // Build function context only if there are context allocated variables.
   int heap_slots = info()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
   if (heap_slots > 0) {
     // Push a new inner context scope for the function.
     Node* closure = GetFunctionClosure();
     Node* inner_context =
         BuildLocalFunctionContext(function_context_.get(), closure);
     ContextScope top_context(this, scope, inner_context);
     CreateGraphBody();
@@ skipping 1976 matching lines @@
 }
 
 
 Node* AstGraphBuilder::BuildLocalFunctionContext(Node* context, Node* closure) {
   // Allocate a new local context.
   const Operator* op = javascript()->CreateFunctionContext();
   Node* local_context = NewNode(op, closure);
 
   // Copy parameters into context if necessary.
   int num_parameters = info()->scope()->num_parameters();
-  for (int i = 0; i < num_parameters; i++) {
-    Variable* variable = info()->scope()->parameter(i);
+  int first_parameter = info()->scope()->has_this_declaration() ? -1 : 0;
+  for (int i = first_parameter; i < num_parameters; i++) {
+    Variable* variable =
+        (i == -1) ? info()->scope()->receiver() : info()->scope()->parameter(i);
     if (!variable->IsContextSlot()) continue;
     // Temporary parameter node. The parameter indices are shifted by 1
     // (receiver is parameter index -1 but environment index 0).
     Node* parameter = NewNode(common()->Parameter(i + 1), graph()->start());
     // Context variable (at bottom of the context chain).
     DCHECK_EQ(0, info()->scope()->ContextChainLength(variable->scope()));
     const Operator* op = javascript()->StoreContext(0, variable->index());
     NewNode(op, local_context, parameter);
   }
 
@@ skipping 761 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8