Add an assert_no_deps variable to GN.

tools/gn/setup.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/setup.h"
 
 #include <stdlib.h>
 #include <algorithm>
 #include <sstream>
 #include <utility>
@@ skipping 13 matching lines @@
 #include "tools/gn/input_file.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/parser.h"
 #include "tools/gn/source_dir.h"
 #include "tools/gn/source_file.h"
 #include "tools/gn/standard_out.h"
 #include "tools/gn/switches.h"
 #include "tools/gn/tokenizer.h"
 #include "tools/gn/trace.h"
 #include "tools/gn/value.h"
+#include "tools/gn/value_extractors.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 extern const char kDotfile_Help[] =
     ".gn file\n"
     "\n"
     "  When gn starts, it will search the current directory and parent\n"
     "  directories for a file called \".gn\". This indicates the source root.\n"
@@ skipping 604 matching lines @@
     err.PrintToStdout();
     return false;
   }
   build_settings_.set_build_config_file(
       SourceFile(build_config_value->string_value()));
 
   // Targets to check.
   const Value* check_targets_value =
       dotfile_scope_.GetValue("check_targets", true);
   if (check_targets_value) {
-    // Fill the list of targets to check.
-    if (!check_targets_value->VerifyTypeIs(Value::LIST, &err)) {
+    check_patterns_.reset(new std::vector<LabelPattern>);
+    ExtractListOfLabelPatterns(*check_targets_value, current_dir,
+                               check_patterns_.get(), &err);
+    if (err.has_error()) {
       err.PrintToStdout();
       return false;
     }
-
-    check_patterns_.reset(new std::vector<LabelPattern>);
-    for (const auto& item : check_targets_value->list_value()) {
-      check_patterns_->push_back(
-          LabelPattern::GetPattern(current_dir, item, &err));
-      if (err.has_error()) {
-        err.PrintToStdout();
-        return false;
-      }
-    }
   }
 
   // Fill exec_script_whitelist.
   const Value* exec_script_whitelist_value =
       dotfile_scope_.GetValue("exec_script_whitelist", true);
   if (exec_script_whitelist_value) {
     // Fill the list of targets to check.
     if (!exec_script_whitelist_value->VerifyTypeIs(Value::LIST, &err)) {
       err.PrintToStdout();
       return false;
     }
     scoped_ptr<std::set<SourceFile>> whitelist(new std::set<SourceFile>);
     for (const auto& item : exec_script_whitelist_value->list_value()) {
       if (!item.VerifyTypeIs(Value::STRING, &err)) {
         err.PrintToStdout();
         return false;
       }
       whitelist->insert(current_dir.ResolveRelativeFile(item, &err));
       if (err.has_error()) {
         err.PrintToStdout();
         return false;
       }
     }
     build_settings_.set_exec_script_whitelist(std::move(whitelist));
   }
 
   return true;
 }