Add initializers for lambdalift proxy fields

If an inner class has proxy fields, we missed so far the assignment sfrom
the proxy parameters in the primary constructor of the class to the proxy
fields.

Test case tries several variations of this.

2 files changed, 19 insertions, 5 deletions

diff --git a/src/dotty/tools/dotc/ast/tpd.scala b/src/dotty/tools/dotc/ast/tpd.scala
index 51011f90b..a35e0e523 100644
--- a/src/dotty/tools/dotc/ast/tpd.scala
+++ b/src/dotty/tools/dotc/ast/tpd.scala
@@ -76,8 +76,13 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
   def Block(stats: List[Tree], expr: Tree)(implicit ctx: Context): Block =
     ta.assignType(untpd.Block(stats, expr), stats, expr)
 
-  def maybeBlock(stats: List[Tree], expr: Tree)(implicit ctx: Context): Tree =
-    if (stats.isEmpty) expr else Block(stats, expr)
+  /** Join `stats` in front of `expr` creating a new block if necessary */
+  def seq(stats: List[Tree], expr: Tree)(implicit ctx: Context): Tree =
+    if (stats.isEmpty) expr
+    else expr match {
+      case Block(estats, eexpr) => cpy.Block(expr)(stats ::: estats, eexpr)
+      case _ => Block(stats, expr)
+    }
 
   def If(cond: Tree, thenp: Tree, elsep: Tree)(implicit ctx: Context): If =
     ta.assignType(untpd.If(cond, thenp, elsep), thenp, elsep)
diff --git a/src/dotty/tools/dotc/transform/LambdaLift.scala b/src/dotty/tools/dotc/transform/LambdaLift.scala
index bffc7458e..41d6f3c43 100644
--- a/src/dotty/tools/dotc/transform/LambdaLift.scala
+++ b/src/dotty/tools/dotc/transform/LambdaLift.scala
@@ -384,14 +384,23 @@ class LambdaLift extends MiniPhase with IdentityDenotTransformer { thisTransform
     private def addFreeParams(tree: Tree, proxies: List[Symbol])(implicit ctx: Context, info: TransformerInfo): Tree = proxies match {
       case Nil => tree
       case proxies =>
+        val sym = tree.symbol
         val ownProxies =
-          if (!tree.symbol.isConstructor) proxies
-          else proxies.map(_.copy(owner = tree.symbol, flags = Synthetic | Param))
+          if (!sym.isConstructor) proxies
+          else proxies.map(_.copy(owner = sym, flags = Synthetic | Param))
         val freeParamDefs = ownProxies.map(proxy =>
           transformFollowingDeep(ValDef(proxy.asTerm).withPos(tree.pos)).asInstanceOf[ValDef])
+        def proxyInit(field: Symbol, param: Symbol) =
+          transformFollowingDeep(ref(field).becomes(ref(param)))
+        def copyParams(rhs: Tree) = {
+          ctx.log(i"copy params ${proxies.map(_.showLocated)}%, %, own = ${ownProxies.map(_.showLocated)}%, %")
+          seq((proxies, ownProxies).zipped.map(proxyInit), rhs)
+        }
         tree match {
           case tree: DefDef =>
-            cpy.DefDef(tree)(vparamss = tree.vparamss.map(freeParamDefs ++ _))
+            cpy.DefDef(tree)(
+                vparamss = tree.vparamss.map(freeParamDefs ++ _),
+                rhs = if (sym.isPrimaryConstructor) copyParams(tree.rhs) else tree.rhs)
           case tree: Template =>
             cpy.Template(tree)(body = freeParamDefs ++ tree.body)
         }