Adding __hash__ for forward compatibility with pybind11 update.

Backward compatible.

Relevant pybind11 change: https://github.com/pybind/pybind11/pull/2291
Note: This pybind11 change makes pybind11 compatible with native Python behavior:
* https://docs.python.org/3/reference/datamodel.html#object.__hash__
* A class that overrides __eq__() and does not define __hash__() will have its __hash__() implicitly set to None.
PiperOrigin-RevId: 327879230
Change-Id: I8573b761ec94e8889b4eb5ac30a71ee0314e6578

tensorflow/python/distribute/values.py

@@ -435,7 +435,7 @@ class DistributedVarOp(object):
             self.traceback == o.traceback and self.type == o.type)
 
   def __hash__(self):
-    return hash((self.name, self.graph, self.traceback, self.type))
+    return hash((self.name, self.graph, tuple(self.traceback), self.type))
 
 
 class DistributedVariable(DistributedDelegate, variables_lib.Variable,

tensorflow/python/util/tf_stack.cc

@@ -127,6 +127,11 @@ PYBIND11_MODULE(_tf_stack, m) {
       // For compatibility with the traceback module.
       .def("__eq__", &FrameSummary::operator==)
       .def("__ne__", &FrameSummary::operator!=)
+      .def("__hash__",
+           [](const FrameSummary& self) {
+             return py::hash(
+                 py::make_tuple(self.filename, self.lineno, self.name));
+           })
       .def("__getitem__",
            [](const FrameSummary& self, const py::object& index) -> py::object {
              return py::make_tuple(self.filename, self.lineno, self.name,

tensorflow/python/util/tf_stack_test.py

@@ -52,6 +52,17 @@ class TFStackTest(test.TestCase):
     another_frame0, _ = tf_stack.extract_stack(limit=2)
     self.assertEqual(frame0, another_frame0)
 
+  def testFrameSummaryEqualityAndHash(self):
+    # Both defined on the same line to produce identical stacks.
+    frame1, frame2 = tf_stack.extract_stack(), tf_stack.extract_stack()
+    self.assertEqual(len(frame1), len(frame2))
+    for f1, f2 in zip(frame1, frame2):
+      self.assertEqual(f1, f2)
+      self.assertEqual(hash(f1), hash(f1))
+      self.assertEqual(hash(f1), hash(f2))
+    self.assertEqual(frame1, frame2)
+    self.assertEqual(hash(tuple(frame1)), hash(tuple(frame2)))
+
 
 def extract_stack(limit=None):
   # Both defined on the same line to produce identical stacks.