SI-8219 Pending test case for unpositioned implicit error

Extracted with tweezers from ScalaTest and Scalacheck implicits.

    % scalac-hash v2.11.0-M7 test/pending/pos/t8219.scala
    error: type mismatch;
     found   : Any
     required: AnyRef
    Note: Any is not implicitly converted to AnyRef.  You can safely
    pattern match `x: AnyRef` or cast `x.asInstanceOf[AnyRef]` to do so.
    error: type mismatch;
     found   : Any
     required: AnyRef
    Note: Any is not implicitly converted to AnyRef.  You can safely
    pattern match `x: AnyRef` or cast `x.asInstanceOf[AnyRef]` to do so.
    two errors found

Author: retronym

test/pending/pos/t8219.scala

@@ -0,0 +1,36 @@
+trait Equalizer[T]
+trait Gen[A]
+
+class Broken {
+  implicit def const[T](x: T): Gen[T] = ???
+  implicit def convertToEqualizer[T](left: T): Equalizer[T] = ???
+
+  def in(a: Any) = ()
+  in {
+    import scala.None // any import will do..
+    "" == ""
+  }
+
+  // We fall into the errant code path above because `Any#==` and `AnyRef#==`
+  // are (currently) overloaded.
+  //
+  // Real classes couldn't get away with that overloading; it would result in
+  // a compiler error because the variants would collapse into an overriding
+  // relationship after erasure.
+  //
+  //
+  // But, a structural type can! This triggers the same error, and served as
+  // a backstop for this test if we change the signatures of `AnyRef#==` to
+  // override `Any#==`.
+  type T = {
+    def a(a: AnyRef): Boolean
+    def a(a: Any): Boolean
+  }
+
+  def t: T = ???
+
+  in {
+    import scala.None // any import will do..
+    t.a("")
+  }
+}