Merge pull request #2879 from retronym/ticket/7785

SI-7785 Preserve TypeVar suspension through TypeMaps

1 files changed, 34 insertions, 0 deletions

diff --git a/test/files/pos/t7785.scala b/test/files/pos/t7785.scala
new file mode 100644
index 0000000000..1de693d137
--- /dev/null
+++ b/test/files/pos/t7785.scala
@@ -0,0 +1,34 @@
+import scala.language._
+
+trait R[+Repr]
+
+trait TraversableOps {
+  implicit val R: R[Nothing] = ???
+
+  // Removing the implicit parameter in both fixes the crash
+  // removing it into one only gives a valid compiler error.
+  trait OpsDup1[Repr] {
+    def force(implicit bf: R[Repr]): Any
+  }
+
+  trait Ops[Repr] extends OpsDup1[Repr] {
+    def force(implicit bf: R[Repr], dummy: DummyImplicit): Any
+  }
+
+  implicit def ct2ops[T, C[+X]](t: C[T]):
+    Ops[C[T]]
+
+  def force[T](t: Option[T]) =
+    // ct2ops(t).force
+    t.force //Fails compilation on 2.10.2.
+
+
+  /* To get a closer look at the crash:
+  :power
+  val foo = typeOf[C].member(TermName("foo"))
+  val pt = analyzer.HasMember(TermName("force"))
+  val instantiated = foo.info.finalResultType.instantiateTypeParams(foo.typeParams, foo.typeParams.map(TypeVar(_)))
+  instantiated <:< pt
+  */
+  def foo[T, C[+X]]: Ops[C[T]]
+}