Remove unused flag Erroneous

Author: smarter

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

@@ -378,9 +378,6 @@ object Flags {
   /** Denotation is in train of being loaded and completed, used to catch cyclic dependencies */
   final val Touched = commonFlag(48, "<touched>")
 
-  /** An error symbol */
-  final val Erroneous = commonFlag(50, "<is-error>")
-
   /** Class has been lifted out to package level, local value has been lifted out to class level */
   final val Lifted = commonFlag(51, "<lifted>")
 
@@ -459,7 +456,7 @@ object Flags {
     Module | Package | Deferred | MethodOrHKCommon | Param | ParamAccessor.toCommonFlags |
     Scala2ExistentialCommon | Mutable.toCommonFlags | Touched | JavaStatic |
     CovariantOrOuter | ContravariantOrLabel | CaseAccessor.toCommonFlags |
-    NonMember | Erroneous | ImplicitCommon | Permanent | Synthetic |
+    NonMember | ImplicitCommon | Permanent | Synthetic |
     SuperAccessorOrScala2x | Inline
 
   /** Flags guaranteed to be set upon symbol creation, or, if symbol is a top-level
@@ -510,7 +507,7 @@ object Flags {
   final val RetainedModuleValAndClassFlags: FlagSet =
     AccessFlags | Package | Case |
     Synthetic | JavaDefined | JavaStatic | Artifact |
-    Erroneous | Lifted | MixedIn | Specialized
+    Lifted | MixedIn | Specialized
 
   /** Flags that can apply to a module val */
   final val RetainedModuleValFlags: FlagSet = RetainedModuleValAndClassFlags |

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

@@ -1476,8 +1476,6 @@ object SymDenotations {
       base.isClass &&
       (  (symbol eq base)
       || (baseClassSet contains base)
-      || (this is Erroneous)
-      || (base is Erroneous)
       )
 
     final override def isSubClass(base: Symbol)(implicit ctx: Context) =

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

@@ -257,10 +257,7 @@ object Types {
     }
 
     /** Is this type produced as a repair for an error? */
-    final def isError(implicit ctx: Context): Boolean = stripTypeVar match {
-      case _: ErrorType => true
-      case tp => (tp.typeSymbol is Erroneous) || (tp.termSymbol is Erroneous)
-    }
+    final def isError(implicit ctx: Context): Boolean = stripTypeVar.isInstanceOf[ErrorType]
 
     /** Is some part of this type produced as a repair for an error? */
     final def isErroneous(implicit ctx: Context): Boolean = existsPart(_.isError, forceLazy = false)