Don't generate named tensor functions to RegistrationFunctions.h (pytorch#26685)

Summary:
Pull Request resolved: pytorch#26685

This prevents XLA from picking up on named tensor APIs. I ran into some
problems while attempting to support dimname overloads in XLA; since we
don't need the first iteration of named tensors to work with XLA this is
OK.

Test Plan: - run CI.

Differential Revision: D17538893

Pulled By: zou3519

fbshipit-source-id: 93d579c93f5b1dc68541c07c4a3d61792859507d

Author: zou3519

aten/src/ATen/function_wrapper.py

@@ -1335,7 +1335,11 @@ def add_namedtensor_enabled_macro(code):
             raise Exception("broadcasting is not yet supported for native functions, "
                             "but specified for function {}", option['name'])
 
-        if BUILD_NAMEDTENSOR or not is_named_tensor_only:
+        # RegistrationDeclarations.h is used downstream in XLA, where XLA uses
+        # it as the "source of truth" for pytorch ops and generates code based
+        # on it. We don't pass named tensor only functions there because XLA
+        # doesn't support them.
+        if not is_named_tensor_only:
             top_env['registration_declarations'].append(
                 REGISTRATION_DECLARATION.substitute(option))
         if (option['use_c10_dispatcher'] != 'no'):