Add output reference to gen written files.

tools/gn/ninja_build_writer.cc

Index: tools/gn/ninja_build_writer.cc
diff --git a/tools/gn/ninja_build_writer.cc b/tools/gn/ninja_build_writer.cc
index 591947d38cae9ca29918c11fc7697625fd56a229..dd24a980f0f341e27366a32ef4dfaf0a53206c8d 100644
--- a/tools/gn/ninja_build_writer.cc
+++ b/tools/gn/ninja_build_writer.cc
@@ -77,6 +77,14 @@ std::string GetSelfInvocationCommand(const BuildSettings* build_settings) {
 #endif
 }
 
+void WriteAnotherFile(std::ostream& out, const base::FilePath& name) {

[Peter Mayo, 2015/07/28 22:37:37]

I'm not sure this name is good enough, but I don't have a better one.

+  EscapeOptions path_escaping;
+  path_escaping.mode = ESCAPE_NINJA_COMMAND;

[Peter Mayo, 2015/07/28 22:37:37]

This mode says it handles one "thing" for ninja, though the name makes it seem
suspect.

+
+  out << " ";

[Dirk Pranke, 2015/07/28 22:35:05]

I probably would've left line 84 out of this function and listed it separately
inside the for loop before line 164, but that's just me.

[Peter Mayo, 2015/07/28 22:41:38]

And 178, and 183.  That's why I snuck it in here, and put the word "another" in
the name.

I would have moved the loop in here too to save reconstructing the EscapeOptions
each time too, but they have subtly different types.

[Dirk Pranke, 2015/07/28 22:43:11]

fair enough. Yeah, I understood the naming.
Yup, understood.

+  EscapeStringToStream(out, FilePathToUTF8(name), path_escaping);
+}
+
 }  // namespace
 
 NinjaBuildWriter::NinjaBuildWriter(
@@ -143,10 +151,19 @@ bool NinjaBuildWriter::RunAndWriteFile(
 void NinjaBuildWriter::WriteNinjaRules() {
   out_ << "rule gn\n";
   out_ << "  command = " << GetSelfInvocationCommand(build_settings_) << "\n";
-  out_ << "  description = Regenerating ninja files\n\n";
+  out_ << "  description = Regenerating ninja files\n";
+  out_ << "  restat = 1\n\n";
+
+  // This rule will regenerate the ninja files when any input file has changed,
+  // or is missing.
+  out_ << "build build.ninja";
+
+  // Other files read by the build.
+  std::vector<SourceFile> written_files = g_scheduler->GetWrittenFiles();
+  for (const auto& written_file : written_files)
+    WriteAnotherFile(out_, build_settings_->GetFullPath(written_file));
 
-  // This rule will regenerate the ninja files when any input file has changed.
-  out_ << "build build.ninja: gn\n"
+  out_ << ": gn\n"
        << "  generator = 1\n"
        << "  depfile = build.ninja.d\n";
 
@@ -158,12 +175,12 @@ void NinjaBuildWriter::WriteNinjaRules() {
   std::vector<base::FilePath> input_files;
   g_scheduler->input_file_manager()->GetAllPhysicalInputFileNames(&input_files);
   for (const auto& input_file : input_files)
-    dep_out_ << " " << FilePathToUTF8(input_file);
+    WriteAnotherFile(dep_out_, input_file);
 
   // Other files read by the build.
   std::vector<base::FilePath> other_files = g_scheduler->GetGenDependencies();
   for (const auto& other_file : other_files)
-    dep_out_ << " " << FilePathToUTF8(other_file);
+    WriteAnotherFile(dep_out_, other_file);
 
   out_ << std::endl;
 }