Explicit cast to uint8 when bool inputs passed to argsort in MAP

[krshrimali]

What does this PR do?

Fixes #981

I can confirm that this is a regression from release 0.7.2, IMO: an explicit cast from torch.bool to torch.uint8 (on CUDA only) while applying torch.argsort should fix this. Looks like PyTorch doesn't support sorting for boolean dtypes on CUDA devices:

// FIXME: remove this check once cub sort supports bool
TORCH_CHECK(self_dtype != ScalarType::Bool,
  "Sort currently does not support bool dtype on CUDA.");

https://github.com/pytorch/pytorch/blob/1a7e43be141ce01469d7605075cb1008bf19abd7/aten/src/ATen/native/cuda/Sort.cpp#L80

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[codecov]

Codecov Report

Merging #983 (98c517a) into master (f8ef656) will decrease coverage by 0%.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #983   +/-   ##
=====================================
- Coverage      95%    95%   -0%     
=====================================
  Files         177    177           
  Lines        7513   7514    +1     
=====================================
- Hits         7139   7127   -12     
- Misses        374    387   +13     

[stancld]

LGTM

[Chris-hughes10]

Thanks for getting this turned around so quickly! As #981 is a blocker for the project my team are working on, is there an estimate on when this will be released?

[Borda]

is there an estimate on when this will be released?

we can do one during this week, just would also include #985 🐰
pls feel free to ping me on slack if I forget... 😇