[iOS/GN] Fix generation of .dSYM for fat binary builds.

build/toolchain/mac/linker_driver.py

 #!/usr/bin/env python
 
 # Copyright 2016 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.
 
 import os
 import os.path
 import shutil
 import subprocess
@@ skipping 167 matching lines @@
   strip_command.append(_FindLinkerOutput(full_args))
   subprocess.check_call(strip_command)
   return []
 
 
 def _FindLinkerOutput(full_args):
   """Finds the output of the linker by looking for the output flag in its
   argument list. As this is a required linker argument, raises an error if it
   cannot be found.
   """
-  return full_args[full_args.index('-o') + 1]
+  # The linker_driver.py script may be used to wrap either the compiler linker
+  # (uses -o to configure the output) or lipo (uses -output to configure the
+  # output). Since wrapping the compiler linker is the most likely possibility
+  # use try/except and fallback to checking for -output if -o is not found.
+  try:
+    output_flag_index = full_args.index('-o')
+  except ValueError:
+    output_flag_index = full_args.index('-output')
+  return full_args[output_flag_index + 1]
 
 
 def _RemovePath(path):
   """Removes the file or directory at |path| if it exists."""
   if os.path.exists(path):
     if os.path.isdir(path):
       shutil.rmtree(path)
     else:
       os.unlink(path)
 
 
 _LINKER_DRIVER_ARG_PREFIX = '-Wcrl,'
 
 """List of linker driver actions. The sort order of this list affects the
 order in which the actions are invoked. The first item in the tuple is the
 argument's -Wcrl,<sub_argument> and the second is the function to invoke.
 """
 _LINKER_DRIVER_ACTIONS = [
     ('dsym,', RunDsymUtil),
     ('unstripped,', RunSaveUnstripped),
     ('strip,', RunStrip),
 ]
 
 
 if __name__ == '__main__':
   Main(sys.argv)
   sys.exit(0)