Test for var declarations in eval which conflict with let

src/runtime/runtime-scopes.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/runtime/runtime-utils.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/frames-inl.h"
 #include "src/isolate-inl.h"
@@ skipping 205 matching lines @@
 
   // TODO(verwaest): Unify the encoding indicating "var" with DeclareGlobals.
   bool is_var = *initial_value == NULL;
   bool is_const = initial_value->IsTheHole();
   bool is_function = initial_value->IsJSFunction();
   DCHECK_EQ(1,
             BoolToInt(is_var) + BoolToInt(is_const) + BoolToInt(is_function));
 
   int index;
   PropertyAttributes attributes;
-  ContextLookupFlags flags = DONT_FOLLOW_CHAINS;
+  ContextLookupFlags flags;
   BindingFlags binding_flags;
+
+  // Check for a conflict with a lexically scoped variable
+  flags = LEXICAL_TEST;

[adamk, 2015/10/05 17:20:36]

Rather than re-assignining this variable it seems like you could just pass the
appropriate value to Lookup in both places.

[Dan Ehrenberg, 2015/10/08 23:01:26]

Done

+  context_arg->Lookup(name, flags, &index, &attributes, &binding_flags);

[adamk, 2015/10/05 17:20:36]

It seems a shame to do this extra context chain walk for cases that aren't
sloppy eval. Is there any way to distinguish that case from other cases (such as
assignments to globals)?

[Dan Ehrenberg, 2015/10/08 23:01:26]

Done

+  if (attributes != ABSENT && (binding_flags == MUTABLE_CHECK_INITIALIZED ||
+                               binding_flags == IMMUTABLE_CHECK_INITIALIZED)) {
+    return ThrowRedeclarationError(isolate, name);
+  }
+
+  flags = DONT_FOLLOW_CHAINS;
   Handle<Object> holder =
       context->Lookup(name, flags, &index, &attributes, &binding_flags);
   if (holder.is_null()) {
     // In case of JSProxy, an exception might have been thrown.
     if (isolate->has_pending_exception()) return isolate->heap()->exception();
   }
 
   Handle<JSObject> object;
   Handle<Object> value =
       is_function ? initial_value
@@ skipping 923 matching lines @@
 
   // Lookup in the initial Object.prototype object.
   Handle<Object> result;
   ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
       isolate, result,
       Object::GetProperty(isolate->initial_object_prototype(), key));
   return *result;
 }
 }  // namespace internal
 }  // namespace v8