Fix XCode emulation when SDK is not installed.

pylib/gyp/xcode_emulation.py

 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """
 This module contains classes that help to emulate xcodebuild behavior on top of
 other build systems, such as make and ninja.
 """
 
 import copy
@@ skipping 1461 matching lines @@
   install_name = xcode_settings.GetInstallName()
   if install_name:
     env['LD_DYLIB_INSTALL_NAME'] = install_name
   install_name_base = xcode_settings.GetInstallNameBase()
   if install_name_base:
     env['DYLIB_INSTALL_NAME_BASE'] = install_name_base
   if XcodeVersion() >= '0500' and not env.get('SDKROOT'):
     sdk_root = xcode_settings._SdkRoot(configuration)
     if not sdk_root:
       sdk_root = xcode_settings._XcodeSdkPath('')
+    if sdk_root is None:
+      sdk_root = ''
     env['SDKROOT'] = sdk_root

[Nico, 2015/06/29 16:25:19]

Is it useful to set SDKROOT to an empty string? Should this just be

  if sdk_root is not None:
    env['SDKROOT'] = sdk_root

[sdefresne, 2015/06/29 16:48:59]

IIUC this CL is to get Xcode emulation working when SDK is not installed. I'm
not sure if it is possible to install Xcode without installing a SDK, and since
this variable is only used by Xcode and its command line tools, I don't think
exporting or not the environment variable has any impact.

I'd tend to favor the code that does not export the variable then.

 
   if not additional_settings:
     additional_settings = {}
   else:
     # Flatten lists to strings.
     for k in additional_settings:
       if not isinstance(additional_settings[k], str):
         additional_settings[k] = ' '.join(additional_settings[k])
   additional_settings.update(env)
 
@@ skipping 108 matching lines @@
       if toolset == 'target':
         iphoneos_config_dict['xcode_settings']['SDKROOT'] = 'iphoneos'
   return targets
 
 def CloneConfigurationForDeviceAndEmulator(target_dicts):
   """If |target_dicts| contains any iOS targets, automatically create -iphoneos
   targets for iOS device builds."""
   if _HasIOSTarget(target_dicts):
     return _AddIOSDeviceConfigurations(target_dicts)
   return target_dicts