Revert "add keyword out for autograd function Concat to match torch.cat (pytorch#1336)" (pytorch#1340)

This reverts commit 71b9dea.

Author: apaszke

test/test_autograd.py

@@ -1074,7 +1074,6 @@ def prod_single_zero(dim_size):
  (Concat, (0,), ((1, S, S), (2, S, S), (3, S, S))),
  (Concat, (-1,), ((S, S, 1), (S, S, 2), (S, S, 3)), 'negdim-1'),
  (Concat, (-2,), ((S, 1, S), (S, 2, S), (S, 3, S)), 'negdim-2'),
- (Concat, (0, None), ((1, S, S), (2, S, S), (3, S, S)), 'out'),
  (Resize, (S * S, S), ((S, S, S),)),
  (Diag, (), ((S, S),), '2d'),
  (Diag, (), ((S,),), '1d'),

torch/autograd/_functions/tensor.py

@@ -301,14 +301,13 @@ def backward(self, grad_output):
 
 class Concat(Function):
 
- def __init__(self, dim, out=None):
+ def __init__(self, dim):
  super(Concat, self).__init__()
  self.dim = dim
- self.out = out
 
  def forward(self, *inputs):
  self.input_sizes = [i.size(self.dim) for i in inputs]
- return torch.cat(inputs, self.dim, out=self.out)
+ return torch.cat(inputs, self.dim)
 
  def backward(self, grad_output):
  return tuple(grad_output.narrow(self.dim, end - size, size) for size, end

torch/autograd/variable.py

@@ -837,8 +837,8 @@ def __hash__(self):
  class _torch(object):
 
  @staticmethod
- def cat(iterable, dim=0, out=None):
- return Concat(dim, out)(*iterable)
+ def cat(iterable, dim=0):
+ return Concat(dim)(*iterable)
 
  @staticmethod
  def normal(means, std=1):