Merge pull request #2432 from retronym/ticket/delayed-init-ref

Warn on selection of vals from DelayedInit subclasses.

3 files changed, 53 insertions, 0 deletions

diff --git a/test/files/neg/delayed-init-ref.check b/test/files/neg/delayed-init-ref.check
new file mode 100644
index 0000000000..42ccabed1b
--- /dev/null
+++ b/test/files/neg/delayed-init-ref.check
@@ -0,0 +1,10 @@
+delayed-init-ref.scala:17: error: Selecting value vall from object O, which extends scala.DelayedInit, is likely to yield an uninitialized value
+  println(O.vall)     // warn
+            ^
+delayed-init-ref.scala:19: error: Selecting value vall from object O, which extends scala.DelayedInit, is likely to yield an uninitialized value
+  println(vall)       // warn
+          ^
+delayed-init-ref.scala:40: error: Selecting value foo from trait UserContext, which extends scala.DelayedInit, is likely to yield an uninitialized value
+    println({locally(()); this}.foo)  // warn (spurious, but we can't discriminate)
+                                ^
+three errors found
diff --git a/test/files/neg/delayed-init-ref.flags b/test/files/neg/delayed-init-ref.flags
new file mode 100644
index 0000000000..7949c2afa2
--- /dev/null
+++ b/test/files/neg/delayed-init-ref.flags
@@ -0,0 +1 @@
+-Xlint -Xfatal-warnings
diff --git a/test/files/neg/delayed-init-ref.scala b/test/files/neg/delayed-init-ref.scala
new file mode 100644
index 0000000000..f2aa804e28
--- /dev/null
+++ b/test/files/neg/delayed-init-ref.scala
@@ -0,0 +1,42 @@
+trait T {
+  val traitVal = ""
+}
+
+object O extends App with T {
+  val vall = ""
+  lazy val lazyy = ""
+  def deff = ""
+
+  println(vall)       // no warn
+  new {
+    println(vall)     // no warn
+  }
+}
+
+object Client {
+  println(O.vall)     // warn
+  import O.vall
+  println(vall)       // warn
+
+  println(O.lazyy)    // no warn
+  println(O.deff)     // no warn
+  println(O.traitVal) // no warn
+}
+
+// Delayed init usage pattern from Specs2
+// See: https://groups.google.com/d/msg/scala-sips/wP6dL8nIAQs/ogjoPE-MSVAJ
+trait Before extends DelayedInit {
+  def before()
+  override def delayedInit(x: => Unit): Unit = { before; x }
+}
+object Spec {
+  trait UserContext extends Before {
+    def before() = ()
+    val foo = "foo"
+  }
+  new UserContext {
+    println(foo)                      // no warn
+    println(this.foo)                 // no warn
+    println({locally(()); this}.foo)  // warn (spurious, but we can't discriminate)
+  }
+}