Make sure we do not have stale entries inside build-dir/packages

dart/tools/make_links.py

 #!/usr/bin/env python
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 
 '''Tool for creating symlinks from SOURCES to TARGET.
 
 For each SOURCE in SOURCES create a link from SOURCE to TARGET.  If a
 SOURCE ends with .../lib, the lib suffix is ignored when determining
 the name of the target link.
 
+Before creating any links, the old entries of the TARGET directory will be
+removed.
+
 Usage:
   python tools/make_links.py OPTIONS TARGET SOURCES...
 '''
 
 import optparse
 import os
+import shutil
 import subprocess
 import sys
 import utils
 
 
 def get_options():
   result = optparse.OptionParser()
   result.add_option("--timestamp_file", "",
       help='Create a timestamp file when done creating the links.',
       default='')
@@ skipping 17 matching lines @@
     return subprocess.call(['mklink', '/j', target, source], shell=True)
   else:
     return subprocess.call(['ln', '-s', source, target])
 
 def create_timestamp_file(options):
   if options.timestamp_file != '':
     dir_name = os.path.dirname(options.timestamp_file)
     if not os.path.exists(dir_name):
       os.mkdir(dir_name)
     open(options.timestamp_file, 'w').close()
-  
+
 
 def main(argv):
   (options, args) = get_options()
   target = os.path.relpath(args[0])
-  if not os.path.exists(target):
-    os.makedirs(target)
+  if os.path.exists(target):
+    # Remove the packages directory if it already exists.
+    # This is necessary, otherwise we can end up having links in there
+    # pointing to directories which no longer exist (on incremental builds).
+    print 'Removing %s' % target
+    shutil.rmtree(target)
+  os.makedirs(target)
   for source in args[1:]:
     # Assume the source directory is named ".../NAME/lib".
     (name, lib) = os.path.split(source)
     if lib != 'lib':
       name = source
     # Remove any addtional path components preceding NAME.
     (path, name) = os.path.split(name)
     if utils.GuessOS() == 'win32':
       source = os.path.relpath(source)
     else:
       source = os.path.relpath(source, start=target)
     exit_code = make_link(source, os.path.join(target, name))
     if exit_code != 0:
       return exit_code
   create_timestamp_file(options)
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv))