Account for the existence of None values in lists of AST nodes. This …

…can happen in Python 3 when keyword-only arguments are used. Fixes #28725.

PiperOrigin-RevId: 253034028

tensorflow/python/autograph/impl/BUILD

@@ -48,6 +48,24 @@ tf_py_test(
     ],
 )
 
+py_test(
+    name = "api_py3_test",
+    srcs = ["api_py3_test.py"],
+    python_version = "PY3",
+    srcs_version = "PY3",
+    tags = [
+        "no_oss_py2",
+        "no_pip",
+        "nopip",
+    ],
+    deps = [
+        ":impl",
+        "//tensorflow/python:client_testlib",
+        "//tensorflow/python/autograph/utils",
+        "//third_party/py/numpy",
+    ],
+)
+
 tf_py_test(
     name = "conversion_test",
     srcs = ["conversion_test.py"],

tensorflow/python/autograph/impl/api_py3_test.py

@@ -0,0 +1,45 @@
+# python3
+# Copyright 2019 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# ==============================================================================
+"""Tests for api module."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+import os
+
+from tensorflow.python.autograph.core import converter
+from tensorflow.python.autograph.impl import api
+from tensorflow.python.framework import constant_op
+from tensorflow.python.platform import test
+
+
+class ApiTest(test.TestCase):
+
+  def test_converted_call_kwonly_args(self):
+
+    def test_fn(*, a):
+      return a
+
+    x = api.converted_call(test_fn, None,
+                           converter.ConversionOptions(recursive=True),
+                           (), {'a': constant_op.constant(-1)})
+    self.assertEqual(-1, self.evaluate(x))
+
+
+if __name__ == '__main__':
+  os.environ['AUTOGRAPH_STRICT_CONVERSION'] = '1'
+  test.main()

tensorflow/python/autograph/pyct/ast_util.py

@@ -283,8 +283,8 @@ def parallel_walk(node, other):
     n = node_stack.pop()
     o = other_stack.pop()
 
-    if (not isinstance(n, (ast.AST, gast.AST, str)) or
-        not isinstance(o, (ast.AST, gast.AST, str)) or
+    if ((not isinstance(n, (ast.AST, gast.AST, str)) and n is not None) or
+        (not isinstance(o, (ast.AST, gast.AST, str)) and n is not None) or
         n.__class__.__name__ != o.__class__.__name__):
       raise ValueError('inconsistent nodes: {} ({}) and {} ({})'.format(
           n, n.__class__.__name__, o, o.__class__.__name__))
@@ -294,6 +294,9 @@ def parallel_walk(node, other):
     if isinstance(n, str):
       assert isinstance(o, str), 'The check above should have ensured this'
       continue
+    if n is None:
+      assert o is None, 'The check above should have ensured this'
+      continue
 
     for f in n._fields:
       n_child = getattr(n, f, None)

tensorflow/python/autograph/pyct/pretty_printer.py

@@ -91,7 +91,10 @@ def generic_visit(self, node, name=None):
           self._print('%s%s=[' % (self._indent(), self._field(f)))
           self.indent_lvl += 1
           for n in v:
-            self.generic_visit(n)
+            if n is not None:
+              self.generic_visit(n)
+            else:
+              self._print('%sNone' % (self._indent()))
           self.indent_lvl -= 1
           self._print('%s]' % (self._indent()))
         else:
@@ -101,7 +104,10 @@ def generic_visit(self, node, name=None):
           self._print('%s%s=(' % (self._indent(), self._field(f)))
           self.indent_lvl += 1
           for n in v:
-            self.generic_visit(n)
+            if n is not None:
+              self.generic_visit(n)
+            else:
+              self._print('%sNone' % (self._indent()))
           self.indent_lvl -= 1
           self._print('%s)' % (self._indent()))
         else: