SI-9074 Fix generic substitution with package objects, overloading

Takes a leaf out of dotty's book [1] and makes `asSeenFrom`
transparently change the prefix from the package class to the
package object when needed.

This fixes generic subsitution during overload resolution, as
reported in SI-9074.

This subsumes the former fix for SI-6225, which is removed here.

[1] https://github.com/lampepfl/dotty/pull/282

1 files changed, 15 insertions, 0 deletions

diff --git a/test/files/pos/t9074b.scala b/test/files/pos/t9074b.scala
new file mode 100644
index 0000000000..dadcebf399
--- /dev/null
+++ b/test/files/pos/t9074b.scala
@@ -0,0 +1,15 @@
+trait Echo [T] {
+  def echo(t: T): Unit
+}
+
+trait IntEcho extends Echo[Int] {
+  def echo(t: Int) = println(t)
+}
+
+object echo extends IntEcho
+package object echo1  extends IntEcho
+
+object App extends App {
+  echo.echo(1)
+  echo1.echo(1)
+}