Ambiguous implicits for one empty enum case

[sake92]

If you have exactly one case with no parameter list you get ambiguous implicits.
If there are 2 cases it works, or if you have empty parens:

enum Works1 derives Eq:
  case Red, Blue

enum Works2 derives Eq:
  case Red()

enum Nope derives Eq: // ambigous implicits
  case Red

Not sure if there's any workarounds, first time I'm using shapeless.
Amazing library btw! 😃

Repro:
https://scastie.scala-lang.org/edoI6AKPQIKjuFM6vzzsWg

[andrzejressel]

I was doing some tests and it seems Shapeless for some reason really does not like enums without type parameters:

• https://github.com/andrzejressel/shapeless-3/commit/0e8df3bde9bb2023eb752e8abc3bd50fc267e82b - test does not pass
• https://github.com/andrzejressel/shapeless-3/commit/ddec85e9e26c53f258872dfc378dd5a3bc3c74a8 - test passes

[liewhite]

It can be workaround by typeclass lookup priority. Such as put product derives and coproduct derives in an object hierarchy

[joroKr21]

Fixed upstream - thanks @andrzejressel 🥳 scala/scala3#14525