Support private values in GN.

tools/gn/loader.cc

Index: tools/gn/loader.cc
diff --git a/tools/gn/loader.cc b/tools/gn/loader.cc
index 4cca2ce71b2805f5eeb9004a55cba0a0630c2853..1e9e76fdb14195b98930dd97b06b781ae416281e 100644
--- a/tools/gn/loader.cc
+++ b/tools/gn/loader.cc
@@ -19,6 +19,19 @@
 #include "tools/gn/source_file.h"
 #include "tools/gn/trace.h"
 
+namespace {
+
+void ClearPrivateVariables(Scope* scope) {

[cjhopman, 2014/05/14 16:42:43]

Why not just add this on Scope?

[brettw, 2014/05/15 19:44:15]

Done.

+  std::vector<base::StringPiece> variables;
+  scope->GetCurrentScopeVariables(&variables);
+  for (size_t i = 0; i < variables.size(); i++) {
+    if (Scope::IsPrivateVar(variables[i]))
+      scope->DeleteValue(variables[i]);
+  }
+}
+
+}  // namespace
+
 // Identifies one time a file is loaded in a given toolchain so we don't load
 // it more than once.
 struct LoaderImpl::LoadID {
@@ -245,6 +258,9 @@ void LoaderImpl::BackgroundLoadFile(const Settings* settings,
   if (err.has_error())
     g_scheduler->FailWithError(err);
 
+  if (!our_scope.CheckForUnusedVars(&err))
+    g_scheduler->FailWithError(err);
+
   // Pass all of the items that were defined off to the builder.
   for (size_t i = 0; i < collected_items.size(); i++)
     settings->build_settings()->ItemDefined(collected_items[i]->Pass());
@@ -285,6 +301,11 @@ void LoaderImpl::BackgroundLoadBuildConfig(
   Err err;
   root_block->ExecuteBlockInScope(base_config, &err);
 
+  // Clear all private variables left in the scope. We want the root build
+  // config to be like a .gni file in that variables beginning with an
+  // underscore aren't exported.
+  ClearPrivateVariables(base_config);
+
   trace.Done();
 
   if (err.has_error())