Allow GN configs to have sub-configs.

tools/gn/functions.cc

 // Copyright (c) 2013 The Chromium 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 "tools/gn/functions.h"
 
 #include <iostream>
 
 #include "base/environment.h"
 #include "base/strings/string_util.h"
 #include "tools/gn/config.h"
 #include "tools/gn/config_values_generator.h"
 #include "tools/gn/err.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scheduler.h"
 #include "tools/gn/scope.h"
 #include "tools/gn/settings.h"
 #include "tools/gn/template.h"
 #include "tools/gn/token.h"
 #include "tools/gn/value.h"
+#include "tools/gn/value_extractors.h"
+#include "tools/gn/variables.h"
 
 namespace {
 
 // Some functions take a {} following them, and some don't. For the ones that
 // don't, this is used to verify that the given block node is null and will
 // set the error accordingly if it's not. Returns true if the block is null.
 bool VerifyNoBlockForFunctionCall(const FunctionCallNode* function,
                                   const BlockNode* block,
                                   Err* err) {
   if (!block)
@@ skipping 260 matching lines @@
 
   if (g_scheduler->verbose_logging())
     g_scheduler->Log("Defining config", label.GetUserVisibleName(true));
 
   // Create the new config.
   scoped_ptr<Config> config(new Config(scope->settings(), label));
   config->set_defined_from(function);
   if (!Visibility::FillItemVisibility(config.get(), scope, err))
     return Value();
 
-  // Fill it.
+  // Fill the flags and such.
   const SourceDir& input_dir = scope->GetSourceDir();
-  ConfigValuesGenerator gen(&config->config_values(), scope, input_dir, err);
+  ConfigValuesGenerator gen(&config->own_values(), scope, input_dir, err);
   gen.Run();
   if (err->has_error())
     return Value();
 
+  // Read sub-configs.
+  const Value* configs_value = scope->GetValue(variables::kConfigs, true);
+  if (configs_value) {
+    ExtractListOfUniqueLabels(*configs_value, scope->GetSourceDir(),
+                              ToolchainLabelForScope(scope),
+                              &config->configs(), err);
+  }
+  if (err->has_error())
+    return Value();
+
   // Save the generated item.
   Scope::ItemVector* collector = scope->GetItemCollector();
   if (!collector) {
     *err = Err(function, "Can't define a config in this context.");
     return Value();
   }
   collector->push_back(config.release());
 
   return Value();
 }
@@ skipping 543 matching lines @@
   }
 
   // Otherwise it's a no-block function.
   if (!VerifyNoBlockForFunctionCall(function, block, err))
     return Value();
   return found_function->second.no_block_runner(scope, function,
                                                 args.list_value(), err);
 }
 
 }  // namespace functions