Add compatibility unpickler for python 3, use it in test

theano/misc/pkl_utils.py

@@ -13,6 +13,8 @@ __license__ = "3-clause BSD"
 import pickle
 import sys
 import theano
+from theano.compat import PY3
+from theano.compat.six import string_types
 
 
 sys.setrecursionlimit(3000)
@@ -46,3 +48,50 @@ class StripPickler(Pickler):
                 del obj.__dict__['__doc__']
 
         return Pickler.save(self, obj)
+
+
+# Make an unpickler that tries encoding byte streams before raising TypeError.
+# This is useful with python 3, in order to unpickle files created with
+# python 2.
+# This code is taken from Pandas, https://github.com/pydata/pandas,
+# under the same 3-clause BSD license.
+def load_reduce(self):
+    stack = self.stack
+    args = stack.pop()
+    func = stack[-1]
+    try:
+        value = func(*args)
+    except Exception:
+        # try to reencode the arguments
+        if self.encoding is not None:
+            new_args = []
+            for arg in args:
+                if isinstance(arg, string_types):
+                    new_args.append(arg.encode(self.encoding))
+                else:
+                    new_args.append(arg)
+            args = tuple(new_args)
+            try:
+                stack[-1] = func(*args)
+                return
+            except Exception:
+                pass
+
+        if self.is_verbose:
+            print(sys.exc_info())
+            print(func, args)
+
+        raise
+
+    stack[-1] = value
+
+
+if PY3:
+    class CompatUnpickler(pickle._Unpickler):
+        pass
+
+    # Register `load_reduce` defined above in CompatUnpickler
+    CompatUnpickler.dispatch[pickle.REDUCE[0]] = load_reduce
+else:
+    class CompatUnpickler(pickle.Unpickler):
+        pass

theano/tensor/tests/test_opt.py

@@ -15,7 +15,7 @@ from numpy.testing.noseclasses import KnownFailureTest
 
 import theano
 import theano.scalar as scal
-from theano.compat.six import StringIO
+from theano.compat.six import PY3, StringIO
 from theano import compile
 from theano.compile import deep_copy_op, DeepCopyOp
 from theano import config
@@ -2659,8 +2659,19 @@ class test_shapeoptimizer(unittest.TestCase):
 
         pkl_filename = os.path.join(os.path.dirname(theano.__file__),
                                     'tensor', 'tests', 'shape_opt_cycle.pkl')
-        fn_args = pickle.load(open(pkl_filename, "rb"))
-        theano.function(**fn_args)
+        # Due to incompatibilities between python 2 and 3 in the format
+        # of pickled numpy ndarray, we have to force an encoding
+        from theano.misc.pkl_utils import CompatUnpickler
+        pkl_file = open(pkl_filename, "rb")
+        try:
+            if PY3:
+                u = CompatUnpickler(pkl_file, encoding="latin1")
+            else:
+                u = CompatUnpickler(pkl_file)
+            fn_args = u.load()
+            theano.function(**fn_args)
+        finally:
+            pkl_file.close()
 
 
 class test_assert(utt.InferShapeTester):