Merge pull request #777 from retronym/ticket/2796

SI-2796 Warn if early definitions are used with a trait.

3 files changed, 33 insertions, 0 deletions

diff --git a/test/files/neg/t2796.check b/test/files/neg/t2796.check
new file mode 100644
index 0000000000..aeb18497ed
--- /dev/null
+++ b/test/files/neg/t2796.check
@@ -0,0 +1,4 @@
+t2796.scala:7: error: Implementation restriction: early definitions in traits are not initialized before the super class is initialized.
+  val abstractVal = "T1.abstractVal" // warn
+      ^
+one error found
diff --git a/test/files/neg/t2796.flags b/test/files/neg/t2796.flags
new file mode 100644
index 0000000000..e8fb65d50c
--- /dev/null
+++ b/test/files/neg/t2796.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
\ No newline at end of file
diff --git a/test/files/neg/t2796.scala b/test/files/neg/t2796.scala
new file mode 100644
index 0000000000..3bcc9df562
--- /dev/null
+++ b/test/files/neg/t2796.scala
@@ -0,0 +1,28 @@
+trait Base {
+  val abstractVal: String
+  final val useAbstractVal = abstractVal
+}
+
+trait T1 extends {
+  val abstractVal = "T1.abstractVal" // warn
+} with Base
+
+trait T2 extends {
+  type X = Int                       // okay
+} with Base
+
+
+class C1 extends {
+  val abstractVal = "C1.abstractVal" // okay
+} with Base
+
+object Test {
+  def main(args: Array[String]) {
+    assert(new C1 ().useAbstractVal == "C1.abstractVal")
+    // This currently fails. a more ambitious approach to this ticket would add $earlyinit$
+    // to traits and call it from the right places in the right order.
+    //
+    // For now, we'll just issue a warning.
+    assert(new T1 {}.useAbstractVal == "T1.abstractVal")
+  }
+}