MAINT: address review comments

Author: ev-br

torch_np/_detail/_reductions.py

@@ -173,7 +173,7 @@ def var(tensor, axis=None, dtype=None, ddof=0, *, where=NoValue):
 #   2. axis=None ravels (cf concatenate)
 
 
-def cumprod(tensor, axis=None, dtype=None):
+def cumprod(tensor, axis, dtype=None):
     if dtype == torch.bool:
         dtype = _scalar_types.default_int_type.dtype
     if dtype is None:
@@ -184,7 +184,7 @@ def cumprod(tensor, axis=None, dtype=None):
     return result
 
 
-def cumsum(tensor, axis=None, dtype=None):
+def cumsum(tensor, axis, dtype=None):
     if dtype == torch.bool:
         dtype = _scalar_types.default_int_type.dtype
     if dtype is None:

torch_np/_detail/_util.py

@@ -111,7 +111,8 @@ def expand_shape(arr_shape, axis):
 def apply_keepdims(tensor, axis, ndim):
     if axis is None:
         # tensor was a scalar
-        tensor = torch.full((1,) * ndim, fill_value=tensor.item(), dtype=tensor.dtype)
+        shape = (1,) * ndim
+        tensor = tensor.expand(shape).contiguous()  # avoid CUDA synchronization
     else:
         shape = expand_shape(tensor.shape, axis)
         tensor = tensor.reshape(shape)

torch_np/_helpers.py

@@ -56,7 +56,10 @@ def result_or_out(result_tensor, out_array=None, promote_scalar=False):
             if promote_scalar and can_fit:
                 result_tensor = result_tensor.squeeze()
             else:
-                raise ValueError("Bad size of the out array.")
+                raise ValueError(
+                    f"Bad size of the out array: out.shape = {out.shape} "
+                    f"while result.shape = {result_tensor.shape}."
+                )
         out_tensor = out_array.get()
         out_tensor.copy_(result_tensor)
         return out_array