Make Root's +extensionRegistry generation smarter.

At generation time, walk the file's dependencies to see what really contains
extensions so we can generate more minimal code that only links together the
roots that provided extensions. Gets a bunch of otherwise noop code out of
the call flow when the roots are +initialized.

1 files changed, 2 insertions, 12 deletions

diff --git a/objectivec/google/protobuf/Api.pbobjc.m b/objectivec/google/protobuf/Api.pbobjc.m
index cd37edaa..e73ecf85 100644
--- a/objectivec/google/protobuf/Api.pbobjc.m
+++ b/objectivec/google/protobuf/Api.pbobjc.m
@@ -31,18 +31,8 @@
 
 @implementation GPBApiRoot
 
-+ (GPBExtensionRegistry*)extensionRegistry {
-  // This is called by +initialize so there is no need to worry
-  // about thread safety and initialization of registry.
-  static GPBExtensionRegistry* registry = nil;
-  if (!registry) {
-    GPBDebugCheckRuntimeVersion();
-    registry = [[GPBExtensionRegistry alloc] init];
-    [registry addExtensions:[GPBSourceContextRoot extensionRegistry]];
-    [registry addExtensions:[GPBTypeRoot extensionRegistry]];
-  }
-  return registry;
-}
+// No extensions in the file and none of the imports (direct or indirect)
+// defined extensions, so no need to generate +extensionRegistry.
 
 @end