Mitigates NaN not comparing equal in graphdefs by using SerializeToString.

PiperOrigin-RevId: 345598223

tensorflow_federated/python/core/impl/compiler/tree_analysis.py

@@ -465,7 +465,13 @@ def _compiled_comp_equal(comp_1, comp_2):
 
   graphdef_1 = serialization_utils.unpack_graph_def(tensorflow_1.graph_def)
   graphdef_2 = serialization_utils.unpack_graph_def(tensorflow_2.graph_def)
-  return graphdef_1 == graphdef_2
+  # TODO(b/174605105): We prefer to mitigate nans comparing unequal for now,
+  # given the severity of TFF's failure to handle this violation of its
+  # assumption that trees_equal is an equivalence relation on its ASTs. But this
+  # is not a long-term solution. To replace with more legitimate proto
+  # comparison which treats nans as equal.
+  return graphdef_1.SerializeToString(
+      deterministic=True) == graphdef_2.SerializeToString(deterministic=True)
 
 
 def trees_equal(comp_1, comp_2):

tensorflow_federated/python/core/impl/compiler/tree_analysis_test.py

@@ -710,7 +710,6 @@ class TreesEqualTest(absltest.TestCase):
     self.assertTrue(tree_analysis.trees_equal(tuple_1, tuple_2))
 
   def test_returns_true_for_identical_graphs_with_nans(self):
-    self.skipTest('b/174605105')
     tf_comp1 = _create_tensorflow_graph_with_nan()
     tf_comp2 = _create_tensorflow_graph_with_nan()
     self.assertTrue(tree_analysis.trees_equal(tf_comp1, tf_comp2))