Fixes SI-6500 by making erasure more regular.

With the introduction of value classes, erasure uses specialErasure where a value class C with underlying type T is unboxed to an ErasedValueType. ErasedValue types are eliminated on phase later, in post-erasure. This was done everywhere, except in the parameter types of bridge methods. That was a mistale, because that way  bridge methods could not do the boxing/unboxing logic triggered by ErasedValueTypes.

Note: there is one remaining use of erasure (not specialErasure) in Erasure.scala. I put in a comment why that is OK.

1 files changed, 13 insertions, 0 deletions

diff --git a/test/files/run/t6500.scala b/test/files/run/t6500.scala
new file mode 100644
index 0000000000..03a68a3a24
--- /dev/null
+++ b/test/files/run/t6500.scala
@@ -0,0 +1,13 @@
+object Test extends App {
+  class Box(val value: Int) extends AnyVal
+
+  trait Foo {
+    def append(box: Box): Foo
+  }
+
+  class Bar extends Foo {
+    override def append(box: Box): Bar = this // produces bad forwarder
+  }
+
+  ((new Bar): Foo).append(new Box(0))
+}