Avoid junk produced by Constraint#replace.

There were two instances where a constraint undergoing a replace would still refer
to poly params that are no longer bound after the replace.

1. In an ordering the replaced parameters was n ot removed from the bounds of the others.
2. When a parameter refers to the replaced parameter in a type, (not a TypeBounds), the
replaced parameter was not replaced.

We now have checking in place that in globally committable typer states, TypeVars are not instantiated
to PolyParams and (configurable) that constraints of such typer states are always closed.

Fixes #670.

1 files changed, 26 insertions, 0 deletions

diff --git a/tests/pos/t8230a.scala b/tests/pos/t8230a.scala
new file mode 100644
index 000000000..f878eacf8
--- /dev/null
+++ b/tests/pos/t8230a.scala
@@ -0,0 +1,26 @@
+trait Arr[T]
+object Arr {
+  def apply[T](xs: T): Arr[T]    = null
+  def apply(x: Long) : Arr[Long] = null
+}
+
+object I {
+  implicit def arrToTrav[T] (a: Arr[T])   : Traversable[T]    = null
+  implicit def longArrToTrav(a: Arr[Long]): Traversable[Long] = null
+}
+
+object Test {
+  def foo(t: Traversable[Any]) = {}
+
+  object Okay {
+    Arr("1")
+
+   import I.{ arrToTrav, longArrToTrav }
+   val x = foo(Arr("2"))
+ }
+
+  object Fail {
+//    import I.arrToTrav
+//    foo(Arr("3")) // found String, expected Long
+  }
+}