Scalar function in DataFusion cannot coerce dictionary type inputs

[viirya]

Describe the bug

This is found during debugging #250.

The current input type coercion rule of scalar functions in DataFusion cannot handle Dictionary types. In TPCDS queries, The PR #250 encounters an error on Coalesce function with q8:

Error during planning: Coercion from [Dictionary(Int32, Utf8), Utf8] to the signature VariadicEqual failed

This has to be fixed at DataFusion instead of Comet.

Steps to reproduce

No response

Expected behavior

No response

Additional context

No response

[viirya]

I will go to submit a fix to DataFusion.

[viirya]

This is fixed at DataFusion. I will update the diffs into the forked DataFusion branch.

[viirya]

The diff is updated.