Avoid alias opaques in two other places during Setup

Author: odersky

compiler/src/dotty/tools/dotc/cc/Setup.scala

@@ -116,7 +116,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
    *  convert it to be boxed.
    */
   private def box(tp: Type)(using Context): Type =
-    def recur(tp: Type): Type = tp.dealiasKeepAnnots match
+    def recur(tp: Type): Type = tp.dealiasKeepAnnotsAndOpaques match
       case tp @ CapturingType(parent, refs) =>
         if tp.isBoxed then tp else tp.boxed
       case tp @ AnnotatedType(parent, ann) =>
@@ -574,7 +574,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
         if sym.isClass then
           !sym.isPureClass && sym != defn.AnyClass
         else
-          val tp1 = tp.dealiasKeepAnnots
+          val tp1 = tp.dealiasKeepAnnotsAndOpaques
           if tp1 ne tp then needsVariable(tp1)
           else instanceCanBeImpure(tp1)
       case tp: (RefinedOrRecType | MatchType) =>

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

@@ -1489,7 +1489,7 @@ object Types {
      *  But if we want to see the type from the outside of object IArray we need to
      *  suppress this dealiasing. A test case where this matters is i18909.scala.
      *  Here, we dealias symbol infos at the start of capture checking in operation `fluidify`.
-     *  We have to be careful not to accidentally reveal opqaue aliases when doing so.
+     *  We have to be careful not to accidentally reveal opaque aliases when doing so.
      */
     final def dealiasKeepOpaques(using Context): Type = dealias1(keepNever, keepOpaques = true)