Tighter pattern matching hits the street.

is final and does not conform to the pattern, it will no longer compile.
See all the exciting things you can no longer do:

  "bob".reverse match { case Seq('b', 'o', 'b') => true } // denied!
  "bob".toArray match { case Seq('b', 'o', 'b') => true } // rejected!
  final class Dunk
  def f3(x: Dunk) = x match { case Seq('b', 'o', 'b') => true } // uh-uh!

And so forth.  Review by odersky.

1 files changed, 21 insertions, 0 deletions

diff --git a/test/files/neg/patmat-type-check.check b/test/files/neg/patmat-type-check.check
new file mode 100644
index 0000000000..ab638b616d
--- /dev/null
+++ b/test/files/neg/patmat-type-check.check
@@ -0,0 +1,21 @@
+patmat-type-check.scala:18: error: scrutinee is incompatible with pattern type;
+ found   : Seq[A]
+ required: java.lang.String
+  def f1 = "bob".reverse match { case Seq('b', 'o', 'b') => true } // fail
+                                         ^
+patmat-type-check.scala:19: error: scrutinee is incompatible with pattern type;
+ found   : Seq[A]
+ required: Array[Char]
+  def f2 = "bob".toArray match { case Seq('b', 'o', 'b') => true } // fail
+                                         ^
+patmat-type-check.scala:23: error: scrutinee is incompatible with pattern type;
+ found   : Seq[A]
+ required: Test.Bop2
+  def f3(x: Bop2) = x match { case Seq('b', 'o', 'b') => true } // fail
+                                      ^
+patmat-type-check.scala:27: error: scrutinee is incompatible with pattern type;
+ found   : Seq[A]
+ required: Test.Bop3[T]
+  def f4[T](x: Bop3[T]) = x match { case Seq('b', 'o', 'b') => true } // fail
+                                            ^
+four errors found