Add a check for ExtensionKit EXAppExtensionAttributes in bundles that don't have "extensionkit_extension = True" set.

Cherry-pick: fd0cab4

Author: nglevin

tools/plisttool/plisttool.py

@@ -193,6 +193,12 @@
     'Unexpectedly found key "%s" in target "%s".'
 )
 
+EXTENSIONKIT_KEY_MSG = (
+    'Target "%s" unexpectedly defines %s, which is an ExtensionKit key. '
+    'Did you forget to set "extensionkit_extension = True" on the extension '
+    'rule to properly define an ExtensionKit extension?'
+)
+
 INVALID_VERSION_KEY_VALUE_MSG = (
     'Target "%s" has a %s that doesn\'t meet Apple\'s guidelines: "%s". See '
     'https://developer.apple.com/library/content/technotes/tn2420/_index.html'
@@ -923,6 +929,14 @@ def validate_plist(self, plist):
         raise PlistToolError(
             MISSING_KEY_MSG % (self.target, 'EXExtensionPointIdentifier')
         )
+    else:
+      # Check if the ExtensionKit EXAppExtensionAttributes dictionary has been
+      # set; if it is, then this extension should be built as an ExtensionKit
+      # extension instead of an NSExtension.
+      if 'EXAppExtensionAttributes' in plist:
+        raise PlistToolError(
+            EXTENSIONKIT_KEY_MSG % (self.target, 'EXAppExtensionAttributes')
+        )
 
     # If the version keys are set, they must be valid (even if they were
     # not required).

tools/plisttool/plisttool_unittest.py

@@ -1160,6 +1160,22 @@ def test_missing_app_extension_point_identifier(self):
           },
       })
 
+  def test_unexpected_app_extension_attributes(self):
+    with self.assertRaisesRegex(
+        plisttool.PlistToolError,
+        re.escape(plisttool.EXTENSIONKIT_KEY_MSG % (
+            _testing_target, 'EXAppExtensionAttributes'))):
+      plist = {
+          'NSExtension': {},
+          'EXAppExtensionAttributes': {
+              'EXExtensionPointIdentifier': 'com.apple.generic-extension',
+          },
+      }
+      _plisttool_result({
+          'plists': [plist],
+          'info_plist_options': {},
+      })
+
   def test_missing_short_version(self):
     with self.assertRaisesRegex(
         plisttool.PlistToolError,