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.

5 files changed, 57 insertions, 3 deletions

diff --git a/test/files/neg/bug1878.check b/test/files/neg/bug1878.check
index 5484d675af..f760781fa0 100644
--- a/test/files/neg/bug1878.check
+++ b/test/files/neg/bug1878.check
@@ -1,10 +1,15 @@
 bug1878.scala:3: error: _* may only come last
   val err1 = "" match { case Seq(f @ _*, ',') => f }
                                  ^
+bug1878.scala:3: error: scrutinee is incompatible with pattern type;
+ found   : Seq[A]
+ required: java.lang.String
+  val err1 = "" match { case Seq(f @ _*, ',') => f }
+                                ^
 bug1878.scala:9: error: _* may only come last
   val List(List(_*, arg2), _) = List(List(1,2,3), List(4,5,6))
                  ^
 bug1878.scala:13: error: _* may only come last
     case <p> { _* } </p> =>
                 ^
-three errors found
+four errors found
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
diff --git a/test/files/neg/patmat-type-check.scala b/test/files/neg/patmat-type-check.scala
new file mode 100644
index 0000000000..c6c689b256
--- /dev/null
+++ b/test/files/neg/patmat-type-check.scala
@@ -0,0 +1,28 @@
+object Test
+{
+  def s1 = "bob".toList  match { case Seq('b', 'o', 'b') => true }  // list ok
+
+  // not final, allowed
+  class Bop
+  def s2(x: Bop) = x match { case Seq('b', 'o', 'b') => true }
+
+  // covariance, allowed
+  final class Bop4[+T]
+  def s3[T](x: Bop4[T]) = x match { case Seq('b', 'o', 'b') => true }
+
+  // contravariance, allowed
+  final class Bop5[T, U, -V]
+  def s4[T1, T2](x: Bop5[_, T1, T2]) = x match { case Seq('b', 'o', 'b') => true }
+
+  // String and Array are final/invariant, disallowed
+  def f1 = "bob".reverse match { case Seq('b', 'o', 'b') => true } // fail
+  def f2 = "bob".toArray match { case Seq('b', 'o', 'b') => true } // fail
+
+  // final, no type parameters, should be disallowed
+  final class Bop2
+  def f3(x: Bop2) = x match { case Seq('b', 'o', 'b') => true } // fail
+
+  // final, invariant type parameter, should be disallowed
+  final class Bop3[T]
+  def f4[T](x: Bop3[T]) = x match { case Seq('b', 'o', 'b') => true } // fail
+}
diff --git a/test/files/pos/bug0646.scala b/test/files/pos/bug0646.scala
index 64214f65b1..a56e857223 100644
--- a/test/files/pos/bug0646.scala
+++ b/test/files/pos/bug0646.scala
@@ -10,7 +10,7 @@ object xfor {
     </bks>;
 
   new NodeSeq { val theSeq = books.child }  match {
-    case t @ <title>Blabla</title> => t
+    case t @ Seq(<title>Blabla</title>) => t
   }
 
   //val n: NodeSeq = new NodeSeq { val theSeq = books.child }
diff --git a/test/files/run/withIndex.scala b/test/files/run/withIndex.scala
index 3b9c9e84e5..910b1f1f9e 100644
--- a/test/files/run/withIndex.scala
+++ b/test/files/run/withIndex.scala
@@ -3,7 +3,7 @@ object Test {
     val ary: Array[String] = Array("a", "b", "c")
     val lst: List[String] = List("a", "b", "c")
     val itr: Iterator[String] = lst.iterator
-    val str: Stream[String] = Stream.fromIterator(lst.iterator)
+    val str: Stream[String] = lst.iterator.toStream
 
     Console.println(ary.zipWithIndex.toList)
     Console.println(lst.zipWithIndex.toList)