Regression: tuple inline matching and head/tail about dotty

[sjrd]

That looks expected to me. The previous reduction relied on some unsound behavior of match types, which we fixed since.

[Gedochao]

Seems we are treating it as intentional behaviour. Closing this.

[ncreep]

Thanks for the quick response.

@sjrd, can you please elaborate about this error?
I see there's this superfluous T & String *: EmptyTuple type assigned to tt. Why isn't it just String *: EmptyTuple as implied by the case statement?

Is there some recommended way of working with inline tuple matching that circumvents this error? Or the workaround I mentioned the only way to do it?

For my real use case, I wouldn't mind using unapply in the match directly, but the actual match is on type parameters, like so:

inline def foo[T <: Tuple](t: T) =
  inline t match
    case (xx: h) *: (yy: t)=>
      val x: h = xx
      val y: t = yy

And that doesn't seem to work either as h and t are not recognized as type variables.

Thanks