Use "$direct" instead of just "$" to prevent erasure clashes

Use "$direct" instead of just "$" to prevent erasure clashes of methods
with erased context function results.

Author: odersky

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

@@ -365,7 +365,7 @@ object NameKinds {
   val ExtMethName: SuffixNameKind = new SuffixNameKind(EXTMETH, "$extension")
   val ParamAccessorName: SuffixNameKind = new SuffixNameKind(PARAMACC, "$accessor")
   val ModuleClassName: SuffixNameKind = new SuffixNameKind(OBJECTCLASS, "$", optInfoString = "ModuleClass")
-  val ImplMethName: SuffixNameKind = new SuffixNameKind(IMPLMETH, "$")
+  val DirectMethName: SuffixNameKind = new SuffixNameKind(DIRECT, "$direct")
   val AdaptedClosureName: SuffixNameKind = new SuffixNameKind(ADAPTEDCLOSURE, "$adapted") { override def definesNewName = true }
   val SyntheticSetterName: SuffixNameKind = new SuffixNameKind(SETTER, "_$eq")
 

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

@@ -24,8 +24,9 @@ object NameTags extends TastyFormat.NameTags {
 
   final val ADAPTEDCLOSURE = 31 // Used in Erasure to adapt closures over primitive types.
 
-  final val IMPLMETH = 32       // Used to define methods in implementation classes
-                                // (can probably be removed).
+  final val DIRECT = 32         // Used to define implementations of methods with
+                                // erased context function results that can override some
+                                // other method.
 
   final val PARAMACC = 33       // Used for a private parameter alias
 
@@ -48,7 +49,7 @@ object NameTags extends TastyFormat.NameTags {
     case INITIALIZER => "INITIALIZER"
     case FIELD => "FIELD"
     case EXTMETH => "EXTMETH"
-    case IMPLMETH => "IMPLMETH"
+    case DIRECT => "DIRECT"
     case PARAMACC => "PARAMACC"
     case ADAPTEDCLOSURE => "ADAPTEDCLOSURE"
     case OBJECTCLASS => "OBJECTCLASS"

compiler/src/dotty/tools/dotc/transform/Erasure.scala

@@ -12,7 +12,7 @@ import core.Types._
 import core.Names._
 import core.StdNames._
 import core.NameOps._
-import core.NameKinds.{AdaptedClosureName, BodyRetainerName, ImplMethName}
+import core.NameKinds.{AdaptedClosureName, BodyRetainerName, DirectMethName}
 import core.Scopes.newScopeWith
 import core.Decorators._
 import core.Constants._
@@ -63,10 +63,10 @@ class Erasure extends Phase with DenotTransformer {
             && contextResultsAreErased(ref.symbol)
             && (ref.owner.is(Flags.Trait) || ref.symbol.allOverriddenSymbols.hasNext)
         then
-          // Add a `$` to prevent this method from having the same signature
+          // Add a `$direct` to prevent this method from having the same signature
           // as a method it overrides. We need a bridge between the
           // two methods, so they are not allowed to already override after erasure.
-          ImplMethName(ref.targetName.asTermName)
+          DirectMethName(ref.targetName.asTermName)
         else
           ref.targetName