fix: slicing on GPU

[ianna]

No description provided.

[ianna]

@jpivarski - found the issue :-)
The numpy.ndarray head that is 0 is not passed to the GPU kernel!

awkward/src/awkward/contents/listarray.py

Line 731 in ba9b4d1

head,

in

awkward/src/awkward/contents/listarray.py

Lines 710 to 733 in ba9b4d1

	elif is_integer_like(head):
	assert advanced is None
	nexthead, nexttail = ak._slicing.head_tail(tail)
	lenstarts = self._starts.length
	nextcarry = ak.index.Index64.empty(lenstarts, self._backend.index_nplike)
	assert (
	nextcarry.nplike is self._backend.index_nplike
	and self._starts.nplike is self._backend.index_nplike
	and self._stops.nplike is self._backend.index_nplike
	)
	self._maybe_index_error(
	self._backend[
	"awkward_ListArray_getitem_next_at",
	nextcarry.dtype.type,
	self._starts.dtype.type,
	self._stops.dtype.type,
	](
	nextcarry.data,
	self._starts.data,
	self._stops.data,
	lenstarts,
	head,
	),
	slicer=head,

[ianna]

@martindurant - as discussed at today's awkward-uproot meeting this is a temporary fix. I will rewrite the way we handle this CUDA kernel wrapping it in a Python function and handling the 'at' type correctly.

[martindurant]

+1, please let me know when this is out.

[martindurant]

Any chance of a few more test cases like [:, 1:], [:, :1], [:, 1::2], [:, ::-1] ?