Merge pull request #8226 from dotty-staging/fix-#8219

Fix #8219: Use translucent supertype to decide AnyKindedness

Author: smarter

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

@@ -275,7 +275,7 @@ object Types {
       @tailrec def loop(tp: Type): Boolean = tp match {
         case tp: TypeRef =>
           val sym = tp.symbol
-          if (sym.isClass) sym == defn.AnyKindClass else loop(tp.superType)
+          if (sym.isClass) sym == defn.AnyKindClass else loop(tp.translucentSuperType)
         case tp: TypeProxy =>
           loop(tp.underlying)
         case _ =>

tests/neg/i8219.scala

@@ -0,0 +1,4 @@
+object O{
+  opaque type T[X <: AnyKind] = X
+}
+def m(x: O.T[AnyKind]) = x // error