Relaxed constraint on lower bound and added tests

Author: milessabin

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

@@ -930,7 +930,7 @@ object Contexts {
             // - we don't want TypeComparer constraining these TypeVars
             val poly = PolyType(DepParamName.fresh(sym.name.toTypeName) :: Nil)(
               pt => (sym.info match {
-                case tb @ TypeBounds(lo, hi) if (lo eq defn.NothingType) && hi.isLambdaSub => tb
+                case tb @ TypeBounds(_, hi) if hi.isLambdaSub => tb
                 case _ => TypeBounds.empty
               }) :: Nil,
               pt => defn.AnyType)

tests/pos/i6014.scala

@@ -21,5 +21,37 @@ object Test2 {
   }
 
   implicit val li: List[Int] = List(1, 2, 3)
-  bar[Foo[List]]
+  val lii = bar[Foo[List]]
+}
+
+object Test3 {
+  inline def summon[T] = implicit match {
+    case t: T => t
+  }
+
+  type K1Top = [t] => Any
+
+  class Foo[F <: K1Top]
+
+  inline def bar[T] = inline erasedValue[T] match {
+    case _: Foo[f] => summon[f[Int]]
+  }
+
+  implicit val li: List[Int] = List(1, 2, 3)
+  val lii = bar[Foo[List]]
+}
+
+object Test4 {
+  inline def summon[T] = implicit match {
+    case t: T => t
+  }
+
+  class Foo[F[t] >: List[t]]
+
+  inline def bar[T] = inline erasedValue[T] match {
+    case _: Foo[f] => summon[f[Int]]
+  }
+
+  implicit val li: List[Int] = List(1, 2, 3)
+  val lii = bar[Foo[List]]
 }