Handle supercalls in inner classes correctly

The previous fix was too coarse. We need to move an anonymous function
in a supercall towards the call, we just have to make sure it's not
in the directly enclosing class.

Author: odersky

compiler/src/dotty/tools/dotc/transform/LambdaLift.scala

@@ -143,14 +143,17 @@ class LambdaLift extends MiniPhase with IdentityDenotTransformer { thisTransform
     /** Set `liftedOwner(sym)` to `owner` if `owner` is more deeply nested
      *  than the previous value of `liftedowner(sym)`.
      */
-    def narrowLiftedOwner(sym: Symbol, owner: Symbol)(implicit ctx: Context) =
+    def narrowLiftedOwner(sym: Symbol, owner: Symbol)(implicit ctx: Context): Unit =
       if (sym.maybeOwner.isTerm &&
         owner.isProperlyContainedIn(liftedOwner(sym)) &&
-        !sym.is(InSuperCall) &&
         owner != sym) {
-        ctx.log(i"narrow lifted $sym to $owner")
-        changedLiftedOwner = true
-        liftedOwner(sym) = owner
+        if (sym.is(InSuperCall) && owner.isProperlyContainedIn(sym.enclosingClass))
+          narrowLiftedOwner(sym, sym.enclosingClass)
+        else {
+          ctx.log(i"narrow lifted $sym to $owner")
+          changedLiftedOwner = true
+          liftedOwner(sym) = owner
+        }
       }
 
     /** Mark symbol `sym` as being free in `enclosure`, unless `sym` is defined

tests/run/i2163.scala

@@ -1,9 +1,21 @@
 class Base(f: Int => Int) {
-  println(f(3))
+  def result = f(3)
 }
 
 class Child(x: Int) extends Base(y => x + y)
 
+class Outer(z: Int) {
+  class Base(f: Int => Int) {
+    def result = f(3)
+  }
+
+  class Child(x: Int) extends Base(y => x + y + z)
+}
+
 object Test {
-  def main(args: Array[String]): Unit = new Child(4)
+  def main(args: Array[String]): Unit = {
+    assert(new Child(4).result == 7)
+    val o = new Outer(2)
+    assert(new o.Child(2).result == 7)
+  }
 }