YCM works correctly when 'out' directory is a symlink.

tools/vim/chromium.ycm_extra_conf.py

 # Copyright (c) 2012 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.
 
 # Autocompletion config for YouCompleteMe in Chromium.
 #
 # USAGE:
 #
 #   1. Install YCM [https://github.com/Valloric/YouCompleteMe]
 #          (Googlers should check out [go/ycm])
@@ skipping 20 matching lines @@
 #   * Right now, we only pull the -I and -D flags. That seems to be sufficient
 #     for everything I've used it for.
 #
 #   * That whole ninja & clang thing? We could support other configs if someone
 #     were willing to write the correct commands and a parser.
 #
 #   * This has only been tested on gPrecise.
 
 
 import os
+import os.path
 import subprocess
 
 
 # Flags from YCM's default config.
 flags = [
 '-DUSE_CLANG_COMPLETER',
 '-std=c++11',
 '-x',
 'c++',
 ]
@@ skipping 107 matching lines @@
     else:
       if filename.startswith(blink_root):
         # If this is a Blink file, we can at least try to get a reasonable
         # approximation.
         filename = default_blink_file
       else:
         # If this is a standalone .h file with no source, the best we can do is
         # try to use the default flags.
         return chrome_flags
 
-  # Ninja needs the path to the source file from the output build directory.
-  # Cut off the common part and /.
-  subdir_filename = filename[len(chrome_root)+1:]
-  rel_filename = os.path.join('..', '..', subdir_filename)
+  out_dir = GetNinjaOutputDirectory(chrome_root)
 
-  out_dir = GetNinjaOutputDirectory(chrome_root)
+  # Ninja needs the path to the source file relative to the output build
+  # directory.
+  rel_filename = os.path.relpath(os.path.realpath(filename),

[eroman, 2014/08/29 19:23:22]

much nicer!

+                                 os.path.realpath(out_dir))
 
   # Ask ninja how it would build our source file.
   p = subprocess.Popen(['ninja', '-v', '-C', out_dir, '-t',
                         'commands', rel_filename + '^'],
                        stdout=subprocess.PIPE)
   stdout, stderr = p.communicate()
   if p.returncode:
     return chrome_flags
 
   # Ninja might execute several commands to build something. We want the last
@@ skipping 41 matching lines @@
   """
   chrome_root = FindChromeSrcFromFilename(filename)
   chrome_flags = GetClangCommandFromNinjaForFilename(chrome_root,
                                                      filename)
   final_flags = flags + chrome_flags
 
   return {
     'flags': final_flags,
     'do_cache': True
   }