Fix crash with test_value and empty elemwise

theano/gof/tests/test_compute_test_value.py

@@ -167,6 +167,23 @@ class TestComputeTestValue(unittest.TestCase):
         finally:
             theano.config.compute_test_value = orig_compute_test_value
 
+    def test_empty_elemwise(self):
+        orig_compute_test_value = theano.config.compute_test_value
+        try:
+            theano.config.compute_test_value = 'raise'
+
+            x = theano.shared(numpy.random.rand(0, 6).astype(config.floatX),
+                              'x')
+
+            # should work
+            z = (x + 2) * 3
+            assert hasattr(z.tag, 'test_value')
+            f = theano.function([], z)
+            assert _allclose(f(), z.tag.test_value)
+
+        finally:
+            theano.config.compute_test_value = orig_compute_test_value
+
     def test_constant(self):
         orig_compute_test_value = theano.config.compute_test_value
         try:

theano/tensor/opt.py

@@ -5433,7 +5433,11 @@ def local_elemwise_fusion_op(OP, max_input_fct=lambda node: 1024,
                         else:
                             tmp = scalar.get_scalar_type(ii.dtype).make_variable()
                             try:
-                                tmp.tag.test_value = gof.op.get_test_value(ii).flatten()[0]
+                                tv = gof.op.get_test_value(ii)
+                                if tv.size > 0:
+                                    tmp.tag.test_value = tv.flatten()[0]
+                                else:
+                                    tmp.tag.test_value = tv
                             except AttributeError:
                                 pass
                             tmp_s_input.append(tmp)