Add a --depfile flag that explicitly names the generated depfile.

grit/tool/build.py

Index: grit/tool/build.py
===================================================================
--- grit/tool/build.py	(revision 141)
+++ grit/tool/build.py	(working copy)
@@ -98,8 +98,9 @@
     first_ids_file = None
     whitelist_filenames = []
     target_platform = None
-    dep_dir = None
-    (own_opts, args) = getopt.getopt(args, 'o:D:E:f:w:t:', ('dep-dir=',))
+    depfile = None
+    depdir = None
+    (own_opts, args) = getopt.getopt(args, 'o:D:E:f:w:t:', ('depdir=','depfile='))
     for (key, val) in own_opts:
       if key == '-o':
         self.output_directory = val
@@ -118,8 +119,10 @@
         whitelist_filenames.append(val)
       elif key == '-t':
         target_platform = val
-      elif key == '--dep-dir':
-        dep_dir = val
+      elif key == '--depdir':
+        depdir = val
+      elif key == '--depfile':
+        depfile = val
 
     if len(args):
       print 'This tool takes no tool-specific arguments.'
@@ -151,8 +154,8 @@
     self.res.RunGatherers()
     self.Process()
 
-    if dep_dir:
-      self.GenerateDepfile(opts.input, dep_dir)
+    if depfile and depdir:
+      self.GenerateDepfile(opts.input, depfile, depdir)
 
     return 0
 
@@ -310,11 +313,10 @@
       print self.res.UberClique().missing_translations_
       sys.exit(-1)
 
-  def GenerateDepfile(self, input_filename, dep_dir):
+  def GenerateDepfile(self, input_filename, depfile, depdir):
     '''Generate a depfile that contains the imlicit dependencies of the input
     grd. The depfile will be in the same format as a makefile, and will contain
-    references to files relative to |dep_dir|. It will be put in the same
-    directory as the generated outputs.
+    references to files relative to |depdir|. It will be put in |depfile|.
 
     For example, supposing we have three files in a directory src/
 
@@ -325,23 +327,21 @@
 
     and we run
 
-      grit -i blah.grd -o ../out/gen --dep-dir ../out
+      grit -i blah.grd -o ../out/gen --depdir ../out --depfile ../out/gen/blah.rd.d
 
     from the directory src/ we will generate a depfile ../out/gen/blah.grd.d
     that has the contents
 
       gen/blah.grd.d: ../src/input1.xtb ../src/input2.xtb
 
-    Note that all paths in the depfile are relative to ../out, the dep-dir.
+    Note that all paths in the depfile are relative to ../out, the depdir.
     '''
-    depsfile_basename = os.path.basename(input_filename + '.d')
-    depfile = os.path.abspath(
-        os.path.join(self.output_directory, depsfile_basename))
-    dep_dir = os.path.abspath(dep_dir)
+    depfile = os.path.abspath(depfile)
+    depdir = os.path.abspath(depdir)
     # The path prefix to prepend to dependencies in the depfile.
-    prefix = os.path.relpath(os.getcwd(), dep_dir)
+    prefix = os.path.relpath(os.getcwd(), depdir)
     # The path that the depfile refers to itself by.
-    self_ref_depfile = os.path.relpath(depfile, dep_dir)
+    self_ref_depfile = os.path.relpath(depfile, depdir)
     infiles = self.res.GetInputFiles()
     deps_text = ' '.join([os.path.join(prefix, i) for i in infiles])
     depfile_contents = self_ref_depfile + ': ' + deps_text