test case to verify dependencies on unused but visited identifiers are tracked

sbt/src/sbt-test/source-dependencies/implicit-search/changes/A1.scala

@@ -0,0 +1 @@
+object A 

sbt/src/sbt-test/source-dependencies/implicit-search/changes/A2.scala

@@ -0,0 +1,3 @@
+object A {
+   val x = 1
+}

sbt/src/sbt-test/source-dependencies/implicit-search/changes/B.scala

@@ -0,0 +1,4 @@
+object B {
+  implicit val x: Ordering[Int] = ???
+}
+

sbt/src/sbt-test/source-dependencies/implicit-search/changes/C.scala

@@ -0,0 +1,7 @@
+object C {
+  import A._, B._
+  implicitly[Ordering[Int]]
+
+  def main(args: Array[String]) {}
+}
+

sbt/src/sbt-test/source-dependencies/implicit-search/test

@@ -0,0 +1,9 @@
+$ copy-file changes/A1.scala A.scala
+$ copy-file changes/B.scala B.scala
+$ copy-file changes/C.scala C.scala
+> compile
+-> run
+
+$ copy-file changes/A2.scala A.scala
+> compile
+> run