Lots of work hardening matching on sequences.

one long-standing bug which actually had a test case testing its
bugginess (which is to say, when I fixed the bug, the test case failed.)
This:

-    def doMatch4(xs:Seq[Char]) = xs match {
-      case Seq(x, y, _*) => x::y::Nil
-      case Seq(x, y, z, w) => List(z,w) // redundant!
-    }

...should never have compiled - which must have been recognized
on some level given the "redundant!" comment, but it never made
it into neg/.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/files/neg/pat_unreachable.check b/test/files/neg/pat_unreachable.check
new file mode 100644
index 0000000000..4e1463d591
--- /dev/null
+++ b/test/files/neg/pat_unreachable.check
@@ -0,0 +1,7 @@
+pat_unreachable.scala:5: error: unreachable code
+    case Seq(x, y, z, w) => List(z,w) // redundant!
+                                ^
+pat_unreachable.scala:9: error: unreachable code
+    case Seq(x, y) => List(x, y)
+                          ^
+two errors found