Apply refactorings blocked previously

Apply refactorings that were not possible before because bootstrap compiler
had problems with them.

Author: odersky

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

@@ -20,11 +20,7 @@ object Flags {
     opaque type Flag <: FlagSet = Long
     private[Flags] def Flag(bits: Long): Flag = bits
   }
-  type FlagSet = opaques.FlagSet
-  def FlagSet(bits: Long): FlagSet = opaques.FlagSet(bits)
-  // DOTTY TODO: replace previous 2 lines with
-  //   export opaques.FlagSet
-  // once 0.17 is released and #6721 is in the bootstrap
+  export opaques.FlagSet
 
   type Flag = opaques.Flag
 

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

@@ -187,46 +187,34 @@ object SymDenotations {
       if (isCurrent(fs)) myFlags else flags
 
     /** Has this denotation one of given flag set? */
-    final def is(flag: Flag)(implicit ctx: Context): Boolean = {
-      val toTest = if (isCurrent(flag)) myFlags else flags // TODO: combine these two lines once 0.17 is released and #6706 is in
-      toTest.is(flag)
-    }
+    final def is(flag: Flag)(implicit ctx: Context): Boolean =
+      (if (isCurrent(flag)) myFlags else flags).is(flag)
 
     /** Has this denotation one of the flags in `fs` set? */
-    final def isOneOf(fs: FlagSet)(implicit ctx: Context): Boolean = {
-      val toTest = if (isCurrent(fs)) myFlags else flags // TODO: combine these two lines once 0.17 is released and #6706 is in
-      toTest.isOneOf(fs)
-    }
+    final def isOneOf(fs: FlagSet)(implicit ctx: Context): Boolean =
+      (if (isCurrent(fs)) myFlags else flags).isOneOf(fs)
 
     /** Has this denotation the given flag set, whereas none of the flags
      *  in `butNot` are set?
      */
-    final def is(flag: Flag, butNot: FlagSet)(implicit ctx: Context): Boolean = {
-      val toTest = if (isCurrent(flag) && isCurrent(butNot)) myFlags else flags // TODO: combine these two lines once 0.17 is released and #6706 is in
-      toTest.is(flag, butNot)
-    }
+    final def is(flag: Flag, butNot: FlagSet)(implicit ctx: Context): Boolean =
+      (if (isCurrent(flag) && isCurrent(butNot)) myFlags else flags).is(flag, butNot)
 
     /** Has this denotation one of the flags in `fs` set, whereas none of the flags
      *  in `butNot` are set?
      */
-    final def isOneOf(fs: FlagSet, butNot: FlagSet)(implicit ctx: Context): Boolean = {
-      val toTest = if (isCurrent(fs) && isCurrent(butNot)) myFlags else flags // TODO: combine these two lines once 0.17 is released and #6706 is in
-      toTest.isOneOf(fs, butNot)
-    }
+    final def isOneOf(fs: FlagSet, butNot: FlagSet)(implicit ctx: Context): Boolean =
+      (if (isCurrent(fs) && isCurrent(butNot)) myFlags else flags).isOneOf(fs, butNot)
 
     /** Has this denotation all of the flags in `fs` set? */
-    final def isAllOf(fs: FlagSet)(implicit ctx: Context): Boolean = {
-      val toTest = if (isCurrent(fs)) myFlags else flags // TODO: combine these two lines once 0.17 is released and #6706 is in
-      toTest.isAllOf(fs)
-    }
+    final def isAllOf(fs: FlagSet)(implicit ctx: Context): Boolean =
+      (if (isCurrent(fs)) myFlags else flags).isAllOf(fs)
 
     /** Has this denotation all of the flags in `fs` set, whereas none of the flags
      *  in `butNot` are set?
      */
-    final def isAllOf(fs: FlagSet, butNot: FlagSet)(implicit ctx: Context): Boolean = {
-      val toTest = if (isCurrent(fs) && isCurrent(butNot)) myFlags else flags // TODO: combine these two lines once 0.17 is released and #6706 is in
-      toTest.isAllOf(fs, butNot)
-    }
+    final def isAllOf(fs: FlagSet, butNot: FlagSet)(implicit ctx: Context): Boolean =
+      (if (isCurrent(fs) && isCurrent(butNot)) myFlags else flags).isAllOf(fs, butNot)
 
     /** The type info, or, if symbol is not yet completed, the completer */
     final def infoOrCompleter: Type = myInfo

compiler/src/dotty/tools/dotc/tastyreflect/KernelImpl.scala

@@ -17,8 +17,6 @@ import dotty.tools.dotc.util.SourceFile
 
 import scala.tasty.reflect.Kernel
 
-import delegate Flags.FlagOps // DOTTY problem: this line can be dropped in 0.17 once #6712 is in bootstrap.
-
 class KernelImpl(val rootContext: core.Contexts.Context, val rootPosition: util.SourcePosition) extends Kernel {
 
   private implicit def ctx: core.Contexts.Context = rootContext

compiler/src/dotty/tools/dotc/typer/Variances.scala

@@ -3,7 +3,6 @@ package typer
 
 import core._
 import Types._, Contexts._, Flags._, Symbols._, Annotations._
-import delegate Flags.FlagOps // DOTTY problem: this line can be dropped in 0.17 once #6712 is in bootstrap.
 
 object Variances {