Check for inputs not generated by deps

tools/gn/build_settings.h

 // 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.
 
 #ifndef TOOLS_GN_BUILD_SETTINGS_H_
 #define TOOLS_GN_BUILD_SETTINGS_H_
 
 #include <map>
 #include <set>
 
@@ skipping 76 matching lines @@
 
   // A list of files that can call exec_script(). If the returned pointer is
   // null, exec_script may be called from anywhere.
   const std::set<SourceFile>* exec_script_whitelist() const {
     return exec_script_whitelist_.get();
   }
   void set_exec_script_whitelist(scoped_ptr<std::set<SourceFile>> list) {
     exec_script_whitelist_ = list.Pass();
   }
 
+  // When set (the default), code should perform normal validation of inputs
+  // and structures, like undefined or possibly incorrectly used things. For
+  // some interrogation commands, we don't care about this and actually want
+  // to allow the user to check the structure of the build to solve their
+  // problem, and these checks are undesirable.
+  bool check_for_bad_items() const {
+    return check_for_bad_items_;
+  }
+  void set_check_for_bad_items(bool c) {
+    check_for_bad_items_ = c;
+  }
+
  private:
   base::FilePath root_path_;
   std::string root_path_utf8_;
   base::FilePath secondary_source_path_;
   base::FilePath python_path_;
 
   SourceFile build_config_file_;
   SourceDir build_dir_;
   Args build_args_;
 
   ItemDefinedCallback item_defined_callback_;
   PrintCallback print_callback_;
 
   scoped_ptr<std::set<SourceFile>> exec_script_whitelist_;
 
+  bool check_for_bad_items_;
+
   BuildSettings& operator=(const BuildSettings& other);  // Disallow.
 };
 
 #endif  // TOOLS_GN_BUILD_SETTINGS_H_