Group flag comparison output by file

tools/gn/bin/gyp_flag_compare.py

Index: tools/gn/bin/gyp_flag_compare.py
diff --git a/tools/gn/bin/gyp_flag_compare.py b/tools/gn/bin/gyp_flag_compare.py
index f2ce3c873a688c0f7b94c9e74cbb7c33cafcffa8..f53240fa05dfbd878773b53d9735d8d6190dcb7f 100755
--- a/tools/gn/bin/gyp_flag_compare.py
+++ b/tools/gn/bin/gyp_flag_compare.py
@@ -17,6 +17,8 @@ def FindAndRemoveArgWithValue(command_line, argname):
 
   Modifies |command_line| in place.
   """
+  if argname not in command_line:
+    return ''
   location = command_line.index(argname)
   value = command_line[location + 1]
   command_line[location:location + 2] = []
@@ -58,7 +60,12 @@ def GetFlags(lines):
     include_dirs = [x for x in command_line if x.startswith('-I')]
     dash_f = [x for x in command_line if x.startswith('-f')]
     warnings = [x for x in command_line if x.startswith('-W')]
-    cc_file = [x for x in command_line if x.endswith('.cc') or x.endswith('.c')]
+    cc_file = [x for x in command_line if x.endswith('.cc') or
+                                          x.endswith('.c') or
+                                          x.endswith('.cpp')]
+    if len(cc_file) != 1:
+      print 'Skipping %s' % command_line
+      continue
     assert len(cc_file) == 1
     others = [x for x in command_line if x not in defines and \
                                          x not in include_dirs and \
@@ -78,21 +85,20 @@ def GetFlags(lines):
 
 
 def CompareLists(gyp, gn, name, dont_care=None):
-  """Output any differences between to lists, ignoring anything in
-  |dont_care|."""
+  """Return a report of any differences between two lists, ignoring anything
+  in |dont_care|."""
   if not dont_care:
     dont_care = []
+  output = ''
   if gyp[name] != gn[name]:
-    print '  %s differ:' % name
+    output += '  %s differ:\n' % name
     gyp_set = set(gyp[name]) - set(dont_care)
     gn_set = set(gn[name]) - set(dont_care)
-    print '    In gyp, but not in GN:\n      %s' % '\n      '.join(
-        sorted(gyp_set - gn_set))
-    print '    In GN, but not in gyp:\n      %s' % '\n      '.join(
-        sorted(gn_set - gyp_set))
-    print
-    return True
-  return False
+    output += '    In gyp, but not in GN:\n      %s' % '\n      '.join(
+        sorted(gyp_set - gn_set)) + '\n'
+    output += '    In GN, but not in gyp:\n      %s' % '\n      '.join(
+        sorted(gn_set - gyp_set)) + '\n\n'
+  return output
 
 
 def main():
@@ -107,32 +113,38 @@ def main():
   all_gn_flags = GetFlags(gn)
   gyp_files = set(all_gyp_flags.keys())
   gn_files = set(all_gn_flags.keys())
-  differences = False
-  if gyp_files != gn_files:
+  different_source_list = gyp_files != gn_files
+  if different_source_list:
     print 'Different set of sources files:'
     print '  In gyp, not in GN:\n    %s' % '\n    '.join(
         sorted(gyp_files - gn_files))
     print '  In GN, not in gyp:\n    %s' % '\n    '.join(
         sorted(gn_files - gyp_files))
     print '\nNote that flags will only be compared for files in both sets.\n'
-    differences |= True
   file_list = gyp_files & gn_files
+  files_with_given_differences = {}
   for filename in sorted(file_list):
     gyp_flags = all_gyp_flags[filename]
     gn_flags = all_gn_flags[filename]
-    print filename
-    differences |= CompareLists(gyp_flags, gn_flags, 'dash_f')
-    differences |= CompareLists(gyp_flags, gn_flags, 'defines', dont_care=[
+    differences = CompareLists(gyp_flags, gn_flags, 'dash_f')
+    differences += CompareLists(gyp_flags, gn_flags, 'defines', dont_care=[
         '-DENABLE_PRE_SYNC_BACKUP',
         '-DENABLE_WEBRTC=1',
         '-DUSE_LIBJPEG_TURBO=1',
         '-DUSE_PANGO=1',
         '-DUSE_SYMBOLIZE',
         ])
-    differences |= CompareLists(gyp_flags, gn_flags, 'include_dirs')
-    differences |= CompareLists(gyp_flags, gn_flags, 'warnings')
-    differences |= CompareLists(gyp_flags, gn_flags, 'other')
-  return 1 if differences else 0
+    differences += CompareLists(gyp_flags, gn_flags, 'include_dirs')
+    differences += CompareLists(gyp_flags, gn_flags, 'warnings')
+    differences += CompareLists(gyp_flags, gn_flags, 'other')
+    if differences:
+      files_with_given_differences.setdefault(differences, []).append(filename)
+
+  for diff, files in files_with_given_differences.iteritems():
+    print '\n'.join(sorted(files))
+    print diff
+
+  return 1 if files_with_given_differences or different_source_list else 0
 
 
 if __name__ == '__main__':