[C++] Implement union-like data type for accommodating kernel arguments which may be scalars or arrays

[asfimport]

For example, either argument to the binary operator Add may be scalar or array. Some systems have addressed this issue by using arrays of length 1, but I would prefer that we accommodate this in Arrow's C++ data types

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

_{Note: This issue was originally created as ARROW-1485. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
This was initially done in f2806fa