Simpler way to test if a new symbol overriddes something

Author: allanrenucci

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

@@ -286,11 +286,8 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
         coord = fns.map(_.pos).reduceLeft(_ union _))
     val constr = ctx.newConstructor(cls, Synthetic, Nil, Nil).entered
     def forwarder(fn: TermSymbol, name: TermName) = {
-      var flags = Synthetic | Method | Final
-      def isOverriden(denot: SingleDenotation) = fn.info.overrides(denot.info, matchLoosely = true)
-      val isOverride = parents.exists(_.member(name).hasAltWith(isOverriden))
-      if (isOverride) flags = flags | Override
-      val fwdMeth = fn.copy(cls, name, flags).entered.asTerm
+      val fwdMeth = fn.copy(cls, name, Synthetic | Method | Final).entered.asTerm
+      if (fwdMeth.allOverriddenSymbols.exists(!_.is(Deferred))) fwdMeth.setFlag(Override)
       polyDefDef(fwdMeth, tprefs => prefss => ref(fn).appliedToTypes(tprefs).appliedToArgss(prefss))
     }
     val forwarders = (fns, methNames).zipped.map(forwarder)