have get_constant_value handle the case of Subtensor(Shape) when their is some…

theano/tensor/basic.py

@@ -404,6 +404,15 @@ def get_constant_value(v):
                 ret = get_constant_value(ret)
                 #MakeVector can cast implicitly its input in some case.
                 return theano._asarray(ret, dtype=v.type.dtype)
+
+            # This is needed when we take the grad as the Shape op
+            # are not already changed into MakeVector
+            if (v.owner.inputs[0].owner and
+                isinstance(v.owner.inputs[0].owner.op,
+                           theano.tensor.Shape)):
+                if v.owner.inputs[0].owner.inputs[0].type.broadcastable[v.owner.op.idx_list[0]]:
+                    return numpy.asarray(1)
+
     raise TypeError(v)
 
 

theano/tensor/tests/test_basic.py

@@ -3528,6 +3528,10 @@ class T_get_constant_value(unittest.TestCase):
         self.assertRaises(TypeError, get_constant_value, a[1])
         self.assertRaises(TypeError, get_constant_value, a[2])
 
+        # Test the case SubTensor(Shape(v)) when the dimensions
+        # is broadcastable.
+        v = tensor.row()
+        assert get_constant_value(v.shape[0])==1
 
 if __name__ == '__main__':
     if 1: