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[Other][C++][Compute] inverse_permutation and scatter should accept unsigned integers #54920
Description
Describe the enhancement requested
The compute functions inverse_permutation and scatter accept arrays of indices that are can only be be signed integers. This limits the range of indices that they can accept, and may force the user into doing an unnecessary cast.
For context, scatter is implemented as Take(values, InversePermutation(indices)).
The inverse_permutation kernel explicitly checks for negative indices:
indices = pa.array([0, -1, -2, -3])
pc.inverse_permutation(indices)
# ArrowIndexError: Index out of bounds: -1Additionally,
inverse_permutationhas kernels only for signed integersscatterexplicitly checks the type
In the original PR, @pitrou brought up a concern about codegen size with supporting both, so only signed was implemented (#44394 (comment))
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[-][C++][Compute] `inverse_permutation` and `scatter` should accept unsigned integers[/-][+][Other][C++][Compute] `inverse_permutation` and `scatter` should accept unsigned integers[/+]pitrou commentedon Oct 22, 2026
The code size concern is genuine, but perhaps we can base the signed implementations on the unsigned ones?
ypomortsev commentedon Oct 22, 2026
Right, the signed implementation can use the fact that valid signed values are the same bitwise as unsigned, e.g. pseudocode