Check for inputs not generated by deps

tools/gn/scheduler.h

Index: tools/gn/scheduler.h
diff --git a/tools/gn/scheduler.h b/tools/gn/scheduler.h
index 912ca7e10ad089ccc3db26395adc3d66187d7f8a..4375f6366fdd0bd9986cb1428a1fddcc1f34aa25 100644
--- a/tools/gn/scheduler.h
+++ b/tools/gn/scheduler.h
@@ -5,6 +5,8 @@
 #ifndef TOOLS_GN_SCHEDULER_H_
 #define TOOLS_GN_SCHEDULER_H_
 
+#include <map>
+
 #include "base/atomic_ref_count.h"
 #include "base/basictypes.h"
 #include "base/files/file_path.h"
@@ -47,9 +49,33 @@ class Scheduler {
   // TODO(brettw) this is global rather than per-BuildSettings. If we
   // start using >1 build settings, then we probably want this to take a
   // BuildSettings object so we know the depdency on a per-build basis.
+  // If moved, most of the Add/Get functions below should move as well.
   void AddGenDependency(const base::FilePath& file);
   std::vector<base::FilePath> GetGenDependencies() const;
 
+  // Tracks calls to write_file for resolving with the unknown generated
+  // inputs (see AddUnknownGeneratedInput below).
+  void AddWrittenFile(const SourceFile& file);
+
+  // Unknown generated inputs are files that a target declares as an input
+  // in the output directory, but which aren't generated by any dependency.
+  //
+  // Some of these files will be files written by write_file and will be
+  // GenDependencies (see AddWrittenFile above). There are OK and include
+  // things like response files for scripts. Others cases will be ones where
+  // the file is generated by a target that's not a dependency.
+  //
+  // In order to distinguish these two cases, the checking for these input
+  // files needs to be done after all targets are complete. This also has the
+  // nice side effect that if a target generates the file we can find it and
+  // tell the user which dependency is missing.
+  //
+  // The result returned by GetUnknownGeneratedInputs will not count any files
+  // that were written by write_file during execution.
+  void AddUnknownGeneratedInput(const Target* target, const SourceFile& file);
+  std::multimap<SourceFile, const Target*> GetUnknownGeneratedInputs() const;
+  void ClearUnknownGeneratedInputsAndWrittenFiles();  // For testing.
+
   // We maintain a count of the things we need to do that works like a
   // refcount. When this reaches 0, the program exits.
   void IncrementWorkCount();
@@ -84,8 +110,10 @@ class Scheduler {
   // loop.
   bool has_been_shutdown_;
 
-  // Additional input dependencies. Protected by the lock.
+  // Protected by the lock. See the corresponding Add/Get functions above.
   std::vector<base::FilePath> gen_dependencies_;
+  std::vector<SourceFile> written_files_;
+  std::multimap<SourceFile, const Target*> unknown_generated_inputs_;
 
   DISALLOW_COPY_AND_ASSIGN(Scheduler);
 };