Attempt again to upstream Xcode project version warning suppression, from 1416453003 and 1430573009…

pylib/gyp/generator/xcode.py

Index: pylib/gyp/generator/xcode.py
diff --git a/pylib/gyp/generator/xcode.py b/pylib/gyp/generator/xcode.py
index cf44b179fef8db77e55647703b08367fbb0ffdfd..3136f7c2aa3a7492e0c3b40be0c2d7b9743dd5fc 100644
--- a/pylib/gyp/generator/xcode.py
+++ b/pylib/gyp/generator/xcode.py
@@ -590,6 +590,15 @@ def GenerateOutput(target_list, target_dicts, data, params):
   parallel_builds = generator_flags.get('xcode_parallel_builds', True)
   serialize_all_tests = \
       generator_flags.get('xcode_serialize_all_test_runs', True)
+  upgrade_check_project_version = \
+      generator_flags.get('xcode_upgrade_check_project_version', None)
+
+  # Format upgrade_check_project_version with leading zeros as needed.
+  if upgrade_check_project_version:
+    upgrade_check_project_version = str(upgrade_check_project_version)
+    while len(upgrade_check_project_version) < 4:
+      upgrade_check_project_version = '0' + upgrade_check_project_version
+
   skip_excluded_files = \
       not generator_flags.get('xcode_list_excluded_files', True)
   xcode_projects = {}
@@ -604,9 +613,17 @@ def GenerateOutput(target_list, target_dicts, data, params):
     xcode_projects[build_file] = xcp
     pbxp = xcp.project
 
+    # Set project-level attributes from multiple options
+    project_attributes = {};
     if parallel_builds:
-      pbxp.SetProperty('attributes',
-                       {'BuildIndependentTargetsInParallel': 'YES'})
+      project_attributes['BuildIndependentTargetsInParallel'] = 'YES'
+    if upgrade_check_project_version:
+      project_attributes['LastUpgradeCheck'] = upgrade_check_project_version
+      project_attributes['LastTestingUpgradeCheck'] = \
+          upgrade_check_project_version
+      project_attributes['LastSwiftUpdateCheck'] = \
+          upgrade_check_project_version
+    pbxp.SetProperty('attributes', project_attributes)
 
     # Add gyp/gypi files to project
     if not generator_flags.get('standalone'):