Add PrimitiveForwarders and fix forwarding on value classes.

1 files changed, 51 insertions, 0 deletions

diff --git a/compiler/src/dotty/tools/dotc/transform/PrimitiveForwarders.scala b/compiler/src/dotty/tools/dotc/transform/PrimitiveForwarders.scala
new file mode 100644
index 000000000..d752ce8e7
--- /dev/null
+++ b/compiler/src/dotty/tools/dotc/transform/PrimitiveForwarders.scala
@@ -0,0 +1,51 @@
+package dotty.tools.dotc
+package transform
+
+import core._
+import TreeTransforms._
+import Contexts.Context
+import Flags._
+import SymUtils._
+import Symbols._
+import SymDenotations._
+import Types._
+import Decorators._
+import DenotTransformers._
+import StdNames._
+import NameOps._
+import ast.Trees._
+import util.Positions._
+import Names._
+import collection.mutable
+import ResolveSuper._
+
+/** This phase adds forwarder where mixedin generic and primitive typed methods have a missmatch.
+  *  In particular for every method that is declared both as generic with a primitive type and with a primitive type
+  *    `<mods> def f[Ts](ps1)...(psN): U` in trait M` and
+  *    `<mods> def f[Ts](ps1)...(psN): V = ...` in implemented in N`
+  *    where U is a primitive and V a polymorphic type (or vice versa) needs:
+  *
+  *    <mods> def f[Ts](ps1)...(psN): U = super[N].f[Ts](ps1)...(psN)
+  *
+  *  IMPORTANT: When\If Valhalla happens, we'll need to move mixin before erasure and than this code will need to be rewritten
+  *  as it will instead change super-class.
+  */
+class PrimitiveForwarders extends MiniPhaseTransform with IdentityDenotTransformer { thisTransform =>
+  import ast.tpd._
+
+  override def phaseName: String = "primitiveForwarders"
+
+  override def runsAfter = Set(classOf[ResolveSuper])
+
+  override def transformTemplate(impl: Template)(implicit ctx: Context, info: TransformerInfo) = {
+    val cls = impl.symbol.owner.asClass
+    val ops = new MixinOps(cls, thisTransform)
+    import ops._
+
+    def methodPrimitiveForwarders: List[Tree] =
+      for (meth <- mixins.flatMap(_.info.decls.flatMap(needsPrimitiveForwarderTo)).distinct)
+        yield polyDefDef(implementation(meth.asTerm), forwarder(meth))
+
+    cpy.Template(impl)(body = methodPrimitiveForwarders ::: impl.body)
+  }
+}