raw_random - correct infer_ndim_bcast in one case

theano/tensor/raw_random.py

@@ -254,7 +254,7 @@ def _infer_ndim_bcast(ndim, shape, *args):
     """
 
     # Find the minimum value of ndim required by the *args
-    if len(args) > 0:
+    if args:
         args_ndim = max(arg.ndim for arg in args)
     else:
         args_ndim = 0
@@ -324,11 +324,13 @@ def _infer_ndim_bcast(ndim, shape, *args):
     elif shape is None:
         # The number of drawn samples will be determined automatically,
         # but we need to know ndim
-        v_shape = tensor.constant([], dtype='int64')
-        if ndim is None:
-            ndim = args_ndim
-        bcast = [False]*ndim #TODO: retrieve broadcasting patterns of arguments
-
+        if not args:
+            raise TypeError(('_infer_ndim_bcast cannot infer shape without'
+                ' either shape or args'))
+        template = reduce(lambda a,b:a+b, args)
+        v_shape = template.shape
+        bcast = template.broadcastable
+        ndim = template.ndim
     else:
         v_shape = tensor.as_tensor_variable(shape)
         if ndim is None: