Fix incorrect assumption that all methods have a positional first argument.

PiperOrigin-RevId: 251865772

tensorflow/python/util/function_utils.py

@@ -27,7 +27,7 @@ from tensorflow.python.util import tf_decorator
 from tensorflow.python.util import tf_inspect
 
 
-def _is_bounded_method(fn):
+def _is_bound_method(fn):
   _, fn = tf_decorator.unwrap(fn)
   return tf_inspect.ismethod(fn) and (fn.__self__ is not None)
 
@@ -55,8 +55,11 @@ def fn_args(fn):
     if _is_callable_object(fn):
       fn = fn.__call__
     args = tf_inspect.getfullargspec(fn).args
-    if _is_bounded_method(fn):
-      args.pop(0)  # remove `self` or `cls`
+    if _is_bound_method(fn) and args:
+      # If it's a bound method, it may or may not have a self/cls first
+      # argument; for example, self could be captured in *args.
+      # If it does have a positional argument, it is self/cls.
+      args.pop(0)
   return tuple(args)
 
 

tensorflow/python/util/function_utils_test.py

@@ -50,7 +50,7 @@ class FnArgsTest(test.TestCase):
 
     self.assertEqual(('a', 'b'), function_utils.fn_args(Foo()))
 
-  def test_bounded_method(self):
+  def test_bound_method(self):
 
     class Foo(object):
 
@@ -59,6 +59,15 @@ class FnArgsTest(test.TestCase):
 
     self.assertEqual(('a', 'b'), function_utils.fn_args(Foo().bar))
 
+  def test_bound_method_no_self(self):
+
+    class Foo(object):
+
+      def bar(*args):  # pylint:disable=no-method-argument
+        return args[1] + args[2]
+
+    self.assertEqual((), function_utils.fn_args(Foo().bar))
+
   def test_partial_function(self):
     expected_test_arg = 123
 
@@ -159,7 +168,7 @@ class HasKwargsTest(test.TestCase):
         del x
     self.assertFalse(function_utils.has_kwargs(FooHasNoKwargs()))
 
-  def test_bounded_method(self):
+  def test_bound_method(self):
 
     class FooHasKwargs(object):