Add a test for supercalls in traits.

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

@@ -164,7 +164,7 @@ object TypeErasure {
     else if (sym.isConstructor) outer.addParam(sym.owner.asClass, erase(tp)(erasureCtx))
     else erase.eraseInfo(tp, sym)(erasureCtx) match {
       case einfo: MethodType if sym.isGetter && einfo.resultType.isRef(defn.UnitClass) =>
-        defn.BoxedUnitClass.typeRef
+        MethodType(Nil, Nil, defn.BoxedUnitClass.typeRef)
       case einfo =>
         einfo
     }

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

@@ -50,15 +50,15 @@ import Decorators._
 
   override def transformDefDef(tree: DefDef)(implicit ctx: Context, info: TransformerInfo): Tree = {
     val sym = tree.symbol
-    
+
     def newField = ctx.newSymbol(
       owner = ctx.owner,
       name = sym.name.asTermName.fieldName,
       flags = Private | (if (sym is Stable) EmptyFlags else Mutable),
       info = sym.info.resultType,
       coord = tree.pos).enteredAfter(thisTransform)
-      
-    lazy val field = sym.field.orElse(newField).asTerm    
+
+    lazy val field = sym.field.orElse(newField).asTerm
     if (sym.is(Accessor, butNot = NoFieldNeeded))
       if (sym.isGetter) {
         tree.rhs.changeOwnerAfter(sym, field, thisTransform)

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

@@ -152,8 +152,14 @@ class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
     def traitInits(mixin: ClassSymbol): List[Tree] =
       for (getter <- mixin.info.decls.filter(getr => getr.isGetter && !wasDeferred(getr)).toList)
         yield {
-          // transformFollowing call is needed to make memoize & lazy vals run
-        transformFollowing(DefDef(implementation(getter.asTerm), superRef(initializer(getter)).appliedToNone))
+        // transformFollowing call is needed to make memoize & lazy vals run
+        val rhs = transformFollowing(superRef(initializer(getter)).appliedToNone)
+        // isCurrent: getter is a member of implementing class
+        val isCurrent = getter.is(ExpandedName) || ctx.atPhase(thisTransform) { implicit ctx =>
+          cls.info.member(getter.name).suchThat(_.isGetter).symbol == getter
+        }
+        if (isCurrent) transformFollowing(DefDef(implementation(getter.asTerm), rhs))
+        else rhs
       }
 
     def setters(mixin: ClassSymbol): List[Tree] =

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

@@ -83,7 +83,7 @@ class ResolveSuper extends MiniPhaseTransform with IdentityDenotTransformer { th
     def methodOverrides(mixin: ClassSymbol): List[Tree] = {
       def isOverridden(meth: Symbol) = meth.overridingSymbol(cls).is(Method, butNot = Deferred)
       def needsDisambiguation(meth: Symbol): Boolean =
-        meth.is(Method, butNot = PrivateOrDeferred) &&
+        meth.is(Method, butNot = PrivateOrAccessorOrDeferred) &&
           !isOverridden(meth) &&
           !meth.allOverriddenSymbols.forall(_ is Deferred)
       for (meth <- mixin.info.decls.toList if needsDisambiguation(meth))
@@ -107,5 +107,5 @@ class ResolveSuper extends MiniPhaseTransform with IdentityDenotTransformer { th
     else ddef
   }
 
-  private val PrivateOrDeferred = Private | Deferred
+  private val PrivateOrAccessorOrDeferred = Private | Accessor | Deferred
 }

tests/run/supercalls-traits.scala

@@ -0,0 +1,15 @@
+trait A {
+ def foo = 1
+}
+
+trait B {
+ def foo = 2
+}
+
+class C extends A with B {
+ override def foo = super[A].foo + super[B].foo
+}
+
+object Test {
+ def main(args: Array[String]) = assert(new C().foo == 3)
+}

tests/run/traits-initialization.scala

@@ -0,0 +1,41 @@
+object store {
+  var str = ""
+}
+
+import store._
+
+trait A {
+ str += "a"
+ val i = 2
+ val s = str += 'A'
+ str += '1'
+}
+
+trait B extends A {
+ str += 'b'
+ override val i = 3
+ override val s = str += 'B'
+ str += '2'
+}
+
+class D(sup: Unit) extends A {
+ str += 'd'
+ override val i = 4
+ override val s = str += 'D'
+ str += '3'
+}
+
+class E(sup: Unit) extends A with B {
+ str += 'd'
+ override val i = 5
+ override val s = str += 'E'
+ str += '3'
+}
+
+
+object Test extends D({str += "Z"}) with B {
+ // should only have 2 fields
+ str += 'E'
+ def main(args: Array[String]) = assert(str == "ZaA1dD3bB2E4", str)
+ str += '4'
+}