Pattern matching on Array types, working for re...

Pattern matching on Array types, working for reals.

  def f[T](a: Array[T]) = a match {
    case x: Array[Int]      => x(0)
    case x: Array[Double]   => 2
    // etc.
  }

I'd also like to thank "instantiateTypeVar" for displacing the
mechanical spiders and giant squid beings which used to fill my
nightmares. Now that I know true horror, I welcome the squid.

Closes #2755, review by odersky.

1 files changed, 5 insertions, 2 deletions

diff --git a/test/files/neg/patmat-type-check.scala b/test/files/neg/patmat-type-check.scala
index c6c689b256..26d0409fa0 100644
--- a/test/files/neg/patmat-type-check.scala
+++ b/test/files/neg/patmat-type-check.scala
@@ -14,6 +14,10 @@ object Test
   final class Bop5[T, U, -V]
   def s4[T1, T2](x: Bop5[_, T1, T2]) = x match { case Seq('b', 'o', 'b') => true }
 
+  // free type parameter, allowed
+  final class Bop3[T]
+  def f4[T](x: Bop3[T]) = 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
@@ -23,6 +27,5 @@ object Test
   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
+  def f4[T](x: Bop3[Char]) = x match { case Seq('b', 'o', 'b') => true } // fail
 }