Test for var declarations in eval which conflict with let

src/runtime/runtime-scopes.cc

Index: src/runtime/runtime-scopes.cc
diff --git a/src/runtime/runtime-scopes.cc b/src/runtime/runtime-scopes.cc
index c3928a7703a6f3bd5c37661d888d404be5e93b8f..4d7ea1f47a445e1fe08534497cb9f9e77c556171 100644
--- a/src/runtime/runtime-scopes.cc
+++ b/src/runtime/runtime-scopes.cc
@@ -223,8 +223,18 @@ Object* DeclareLookupSlot(Isolate* isolate, Handle<String> name,
 
   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()) {