[enhancement] priority_sel should support any cases type

[proppy]

What's hard to do? (limit 100 words)

currently priority_sel can only be used w/ scalar type (uN), see:
https://google.github.io/xls/dslx_std/#priority_sel

Current best alternative workaround (limit 100 words)

using one_hot in combination w/ a match expression decoding the one_hot result and cases w/ arbitrary expression allow support for compound type like struct, tuple and array.

Your view of the "best case XLS enhancement" (limit 100 words)

making priority_sel support arbitrary types in the case array.

[ericastor]

This is a good idea for completeness, but it's worth noting that using a match expression will currently work just fine for arbitrary types - and as it happens, it compiles down to a priority_sel.

[proppy]

it's worth noting that using a match expression will currently work just fine for arbitrary types

Yes, I re-discovered this pattern which allow you to encode as priority_sel w/ arbitrary type as a match statement w/ exclusive condition:

match true {
   condition0 => result0,
   condition1 => result1,
   condition2 => result2,
   condition3 => result3,
}

[proppy]

I re-discovered this pattern

Note this is not actually working as stated above, see #1909