add test

Author: nox213

tests/warn/i24246.check

@@ -0,0 +1,8 @@
+-- [E029] Pattern Match Exhaustivity Warning: tests/warn/i24246.scala:8:2 ----------------------------------------------
+8 |  x match { // warn
+  |  ^
+  |  match may not be exhaustive.
+  |
+  |  It would fail on pattern case: ZZ
+  |
+  | longer explanation available when compiling with `-explain`

tests/warn/i24246.scala

@@ -0,0 +1,10 @@
+trait X
+
+sealed trait Y
+case object YY extends Y, X
+case object ZZ extends Y, X
+
+def foo[A <: X & Y](x: A): Unit =
+  x match { // warn
+    case YY => ()
+  }