Better diagnosis for cyclic references caused by implicit search

Since we now allow to drop the explicit type of a local implicit val
it can happen that this causes a cyclic reference, namely when the
typechecking of the right-hand side involves an implicit search.
It's unpractical and fragile to avoid this. Instead we give now
a nice error message explaining the problem and how to fix it in
source code.

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/neg/implicitDefs.scala b/tests/neg/implicitDefs.scala
index 1489344c8..3ec9796e8 100644
--- a/tests/neg/implicitDefs.scala
+++ b/tests/neg/implicitDefs.scala
@@ -8,4 +8,11 @@ object implicitDefs {
   implicit val x = 2 // error: type of implicit definition needs to be given explicitly
   implicit def y(x: Int) = 3 // error: result type of implicit definition needs to be given explicitly
   implicit def z(a: x.type): String = "" // error: implicit conversion may not have a parameter of singleton type
+
+  def foo(implicit x: String) = 1
+
+  def bar() = {
+    implicit val x = foo
+    x
+  }
 }