Merge pull request #3204 from retronym/topic/patmat-classtag-compound

Test case for recently improved unchecked warning

3 files changed, 24 insertions, 0 deletions

diff --git a/test/files/neg/patmat-classtag-compound.check b/test/files/neg/patmat-classtag-compound.check
new file mode 100644
index 0000000000..8a54c935bd
--- /dev/null
+++ b/test/files/neg/patmat-classtag-compound.check
@@ -0,0 +1,6 @@
+patmat-classtag-compound.scala:12: warning: abstract type pattern A is unchecked since it is eliminated by erasure
+    case b: A with Bar => true
+            ^
+error: No warnings can be incurred under -Xfatal-warnings.
+one warning found
+one error found
diff --git a/test/files/neg/patmat-classtag-compound.flags b/test/files/neg/patmat-classtag-compound.flags
new file mode 100644
index 0000000000..144ddac9d3
--- /dev/null
+++ b/test/files/neg/patmat-classtag-compound.flags
@@ -0,0 +1 @@
+-unchecked -Xfatal-warnings
diff --git a/test/files/neg/patmat-classtag-compound.scala b/test/files/neg/patmat-classtag-compound.scala
new file mode 100644
index 0000000000..e2d0df0a02
--- /dev/null
+++ b/test/files/neg/patmat-classtag-compound.scala
@@ -0,0 +1,17 @@
+object Test extends App{
+  trait Bar
+  trait Foo
+  // Failed to give an unchecked warning pre: https://github.com/scala/scala/pull/2848
+  //
+  // Features interacting:
+  //   - implicit class tags to enable type patterns on abstract types
+  //   - type tests on compound types.
+  //
+  // We could try make these work together, but an unchecked warning is okay for now.
+  def x[A: reflect.ClassTag](a: Any): Boolean = a match{
+    case b: A with Bar => true
+    case _ => false
+  }
+  println(x[Foo](new Bar{}))
+  println(x[String](""))
+}