Standardize on followAliases = true

Author: odersky

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

@@ -55,8 +55,6 @@ object ccConfig:
   def useFresh(using Context): Boolean =
     Feature.sourceVersion.stable.isAtLeast(SourceVersion.`3.6`)
 
-  def followAliases(using Context): Boolean =
-    Feature.sourceVersion.stable.isAtLeast(SourceVersion.`3.6`)
 end ccConfig
 
 /** Are we at checkCaptures phase? */

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

@@ -278,7 +278,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
               paramInfos = tp.paramInfos.mapConserve(_.dropAllRetains.bounds),
               resType = this(tp.resType))
           case _ =>
-            if ccConfig.followAliases then mapFollowingAliases(tp) else mapOver(tp)
+            mapFollowingAliases(tp)
         addVar(addCaptureRefinements(normalizeCaptures(tp1)), ctx.owner)
       end apply
     end mapInferred
@@ -366,8 +366,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
             // Map references to capability classes C to C^
             if t.derivesFromCapability && !t.isSingleton && t.typeSymbol != defn.Caps_Exists
             then CapturingType(t, defn.universalCSImpliedByCapability, boxed = false)
-            else normalizeCaptures(
-              if ccConfig.followAliases then mapFollowingAliases(t) else mapOver(t))
+            else normalizeCaptures(mapFollowingAliases(t))
     end toCapturing
 
     def fail(msg: Message) =
@@ -857,8 +856,7 @@ class Setup extends PreRecheck, SymTransformer, SetupAPI:
     case tp @ OrType(tp1, tp2 @ CapturingType(parent2, refs2)) =>
       CapturingType(OrType(tp1, parent2, tp.isSoft), refs2, tp2.isBoxed)
     case tp @ AppliedType(tycon, args)
-    if !defn.isFunctionClass(tp.dealias.typeSymbol)
-      && (!ccConfig.followAliases || (tp.dealias eq tp)) =>
+    if !defn.isFunctionClass(tp.dealias.typeSymbol) && (tp.dealias eq tp) =>
       tp.derivedAppliedType(tycon, args.mapConserve(box))
     case tp: RealTypeBounds =>
       tp.derivedTypeBounds(tp.lo, box(tp.hi))