Merge pull request #4115 from retronym/ticket/8597

SI-8597 Improved pattern unchecked warnings

1 files changed, 21 insertions, 0 deletions

diff --git a/test/files/neg/t8597b.scala b/test/files/neg/t8597b.scala
new file mode 100644
index 0000000000..b29d591cb1
--- /dev/null
+++ b/test/files/neg/t8597b.scala
@@ -0,0 +1,21 @@
+object Unchecked {
+  (null: Any) match {
+    case _: Some[t] =>
+
+      // t is a fresh pattern type variable, despite our attempts to
+      // backtick our way to the enclosing `t`. Under this interpretation,
+      // the absense of an unchecked warning is expected.
+      (null: Any) match {
+        case _: Some[t] => // no warn
+      }
+      (null: Any) match {
+        case _: Some[`t`] => // no warn
+      }
+
+      // here we correctly issue an unchecked warning
+      type T = t
+      (null: Any) match {
+        case _: Some[T] => // warn
+      }
+  }
+}