Tweaks to appliedTo

 - Allow appliedTo over TypeBounds
 - Difference in handling of empty type parameter lists
 - Always consider EtaExpansions in appliedTo

EtaExpanions were not simplified before in Coder.scala and collections.scala.
Need to come back and simplify appliedTo logic.

1 files changed, 11 insertions, 4 deletions

diff --git a/src/dotty/tools/dotc/core/TypeApplications.scala b/src/dotty/tools/dotc/core/TypeApplications.scala
index d7c73c63f..94e09eaf0 100644
--- a/src/dotty/tools/dotc/core/TypeApplications.scala
+++ b/src/dotty/tools/dotc/core/TypeApplications.scala
@@ -118,7 +118,8 @@ object TypeApplications {
    */
   object EtaExpansion {
     def apply(tycon: Type)(implicit ctx: Context) = {
-      if (!Config.newHK) assert(tycon.isEtaExpandableOLD)
+      if (Config.newHK) assert(tycon.typeParams.nonEmpty, tycon)
+      else assert(tycon.isEtaExpandableOLD)
       tycon.EtaExpand(tycon.typeParamSymbols)
     }
 
@@ -729,13 +730,19 @@ class TypeApplications(val self: Type) extends AnyVal {
     }
     assert(args.nonEmpty)
     self.stripTypeVar match {
-      case self: TypeLambda if !args.exists(_.isInstanceOf[TypeBounds]) =>
-        self.instantiate(args)
+      case self: TypeLambda =>
+        if (!args.exists(_.isInstanceOf[TypeBounds])) self.instantiate(args)
+        else self match {
+          case EtaExpansion(selfTycon) => selfTycon.appliedTo(args)
+          case _ => HKApply(self, args)
+        }
       case self: AndOrType =>
         self.derivedAndOrType(self.tp1.appliedTo(args), self.tp2.appliedTo(args))
+      case self: TypeBounds =>
+        self.derivedTypeBounds(self.lo, self.hi.appliedTo(args))
       case self: LazyRef =>
         LazyRef(() => self.ref.appliedTo(args, typParams))
-      case _ if typParams.isEmpty || typParams.head.isInstanceOf[LambdaParam] =>
+      case _ if typParams.nonEmpty && typParams.head.isInstanceOf[LambdaParam] =>
         HKApply(self, args)
       case _ =>
         matchParams(self, typParams, args) match {