Applied review comments

Added suggested changes by myself and @smarter.

Author: odersky

src/dotty/tools/dotc/ast/Trees.scala

@@ -223,7 +223,7 @@ object Trees {
 
     override def toText(printer: Printer) = printer.toText(this)
 
-    override def hashCode(): Int = uniqueId
+    override def hashCode(): Int = uniqueId // for debugging; was: System.identityHashCode(this)
     override def equals(that: Any) = this eq that.asInstanceOf[AnyRef]
   }
 

src/dotty/tools/dotc/core/Symbols.scala

@@ -504,7 +504,7 @@ object Symbols {
     def showName(implicit ctx: Context): String = ctx.nameString(this)
     def showFullName(implicit ctx: Context): String = ctx.fullNameString(this)
 
-    override def hashCode() = id
+    override def hashCode() = id // for debugging.
   }
 
   type TermSymbol = Symbol { type ThisName = TermName }

src/dotty/tools/dotc/transform/Mixin.scala

@@ -109,8 +109,7 @@ class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
 
   private def initializer(sym: Symbol)(implicit ctx: Context): TermSymbol = {
     val initName = if(!sym.is(Lazy)) InitializerName(sym.name.asTermName) else sym.name.asTermName
-    def hasSameLaziness(s: Symbol) = if(sym.is(Lazy)) s.is(Lazy) else !s.is(Lazy)
-    sym.owner.info.decl(initName).suchThat(hasSameLaziness).symbol
+    sym.owner.info.decl(initName).suchThat(_.is(Lazy) == sym.is(Lazy)).symbol
       .orElse(
         ctx.newSymbol(
           sym.owner,