Make sure lazy accessors in traits are not private.

Fixes #1140. Review by @DarkDimius or @smarter.

3 files changed, 15 insertions, 2 deletions

diff --git a/src/dotty/tools/dotc/transform/Mixin.scala b/src/dotty/tools/dotc/transform/Mixin.scala
index 32b268fc7..fc82caf65 100644
--- a/src/dotty/tools/dotc/transform/Mixin.scala
+++ b/src/dotty/tools/dotc/transform/Mixin.scala
@@ -98,8 +98,12 @@ class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
   override def runsAfter: Set[Class[_ <: Phase]] = Set(classOf[Erasure])
 
   override def transformSym(sym: SymDenotation)(implicit ctx: Context): SymDenotation =
-    if (sym.is(Accessor, butNot = Deferred | Lazy) && sym.owner.is(Trait))
-      sym.copySymDenotation(initFlags = sym.flags &~ ParamAccessor | Deferred).ensureNotPrivate
+    if (sym.is(Accessor, butNot = Deferred) && sym.owner.is(Trait)) {
+      val sym1 =
+        if (sym is Lazy) sym
+        else sym.copySymDenotation(initFlags = sym.flags &~ ParamAccessor | Deferred)
+      sym1.ensureNotPrivate
+    }
     else if (sym.isConstructor && sym.owner.is(Trait))
       sym.copySymDenotation(
         name = nme.TRAIT_CONSTRUCTOR,
diff --git a/tests/run/i1140/A_1.scala b/tests/run/i1140/A_1.scala
new file mode 100644
index 000000000..e16a8162d
--- /dev/null
+++ b/tests/run/i1140/A_1.scala
@@ -0,0 +1,4 @@
+trait A {
+  val foo = 0 + x
+  private lazy val x = 1
+}
diff --git a/tests/run/i1140/B_2.scala b/tests/run/i1140/B_2.scala
new file mode 100644
index 000000000..aa576c256
--- /dev/null
+++ b/tests/run/i1140/B_2.scala
@@ -0,0 +1,5 @@
+object Test extends A {
+  def main(args: Array[String]): Unit = {
+    assert(foo == 1)
+  }
+}