return right time (list vs var)

theano/tensor/opt.py

@@ -2032,7 +2032,7 @@ def local_useless_elemwise(node):
 
                 # Copy stack trace from input to constant output
                 copy_stack_trace(node.outputs[0], ret)
-                return ret
+                return [ret]
         elif node.op.scalar_op == theano.scalar.neq and len(node.inputs) == 2:
             if node.inputs[0] == node.inputs[1]:
                 # it is the same var in the graph. That will always be false
@@ -2040,7 +2040,7 @@ def local_useless_elemwise(node):
 
                 # Copy stack trace from input to constant output
                 copy_stack_trace(node.outputs[0], ret)
-                return ret
+                return [ret]
 
         elif node.op.scalar_op == theano.scalar.mul and len(node.inputs) == 1:
             # No need to copy over any stack trace
@@ -2060,8 +2060,8 @@ def local_useless_elemwise(node):
                 const_val = T.extract_constant(node.inputs[0], only_process_constants=True)
                 if not isinstance(const_val, Variable):
                     if const_val == 0:
-                        return T.zeros_like(node.inputs[1], dtype=dtype,
-                                            opt=True)
+                        return [T.zeros_like(node.inputs[1], dtype=dtype,
+                                             opt=True)]
                     else:
                         return [node.inputs[1]]
 
@@ -2069,8 +2069,8 @@ def local_useless_elemwise(node):
                 const_val = T.extract_constant(node.inputs[1], only_process_constants=True)
                 if not isinstance(const_val, Variable):
                     if const_val == 0:
-                        return T.zeros_like(node.inputs[0], dtype=dtype,
-                                            opt=True)
+                        return [T.zeros_like(node.inputs[0], dtype=dtype,
+                                             opt=True)]
                     else:
                         return [node.inputs[0]]
 
@@ -2083,7 +2083,8 @@ def local_useless_elemwise(node):
                     if const_val == 0:
                         return [node.inputs[1]]
                     else:
-                        return T.ones_like(node.inputs[1], dtype=dtype, opt=True)
+                        return [T.ones_like(node.inputs[1], dtype=dtype,
+                                            opt=True)]
 
             if isinstance(node.inputs[1], T.TensorConstant):
                 const_val = T.extract_constant(node.inputs[1], only_process_constants=True)
@@ -2091,12 +2092,13 @@ def local_useless_elemwise(node):
                     if const_val == 0:
                         return [node.inputs[0]]
                     else:
-                        return T.ones_like(node.inputs[0], dtype=dtype, opt=True)
+                        return [T.ones_like(node.inputs[0], dtype=dtype,
+                                            opt=True)]
 
         elif (isinstance(node.op.scalar_op, scalar.XOR) and
               len(node.inputs) == 2):
             if node.inputs[0] is node.inputs[1]:
-                return T.zeros_like(node.inputs[0], dtype=dtype, opt=True)
+                return [T.zeros_like(node.inputs[0], dtype=dtype, opt=True)]
 
 
 @register_specialize