treat type lambdas of the form [T, ...] =>> U[T, ...] as eta-expanded U

Author: pweisenburger

compiler/src/dotty/tools/dotc/core/TypeApplications.scala

@@ -57,8 +57,7 @@ object TypeApplications {
 
     def unapply(tp: Type)(using Context): Option[Type] = tp match
       case tp @ HKTypeLambda(tparams, AppliedType(fn: Type, args))
-      if fn.typeSymbol.isClass
-         && tparams.hasSameLengthAs(args)
+      if tparams.hasSameLengthAs(args)
          && args.lazyZip(tparams).forall((arg, tparam) => arg == tparam.paramRef)
          && weakerBounds(tp, fn.typeParams) => Some(fn)
       case _ => None