Use correct flags for anonymous given parameters in classes

Author: odersky

compiler/src/dotty/tools/dotc/ast/untpd.scala

@@ -415,9 +415,9 @@ object untpd extends Trees.Instance[Untyped] with UntypedTreeInfo {
     vdef.withMods(mods | Param)
   }
 
-  def makeSyntheticParameter(n: Int = 1, tpt: Tree = null, flags: FlagSet = EmptyFlags)(implicit ctx: Context): ValDef =
+  def makeSyntheticParameter(n: Int = 1, tpt: Tree = null, flags: FlagSet = SyntheticTermParam)(implicit ctx: Context): ValDef =
     ValDef(nme.syntheticParamName(n), if (tpt == null) TypeTree() else tpt, EmptyTree)
-      .withFlags(flags | SyntheticTermParam)
+      .withFlags(flags)
 
   def lambdaAbstract(tparams: List[TypeDef], tpt: Tree)(implicit ctx: Context): Tree =
     if (tparams.isEmpty) tpt else LambdaTypeTree(tparams, tpt)

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -2247,7 +2247,8 @@ object Parsers {
           val tps = commaSeparated(() => annotType())
           var counter = nparams
           def nextIdx = { counter += 1; counter }
-          val params = tps.map(makeSyntheticParameter(nextIdx, _, Given | Implicit))
+          val paramFlags = if (ofClass) Private | Local | ParamAccessor else Param
+          val params = tps.map(makeSyntheticParameter(nextIdx, _, paramFlags | Synthetic | Given | Implicit))
           params :: recur(firstClause = false, nparams + params.length)
         }
         else Nil