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.

6 files changed, 94 insertions, 20 deletions

diff --git a/test/files/neg/patmat-type-check.check b/test/files/neg/patmat-type-check.check
index ab638b616d..8f81cede8f 100644
--- a/test/files/neg/patmat-type-check.check
+++ b/test/files/neg/patmat-type-check.check
@@ -1,21 +1,21 @@
-patmat-type-check.scala:18: error: scrutinee is incompatible with pattern type;
+patmat-type-check.scala:22: 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;
+patmat-type-check.scala:23: 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;
+patmat-type-check.scala:27: 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;
+patmat-type-check.scala:30: 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
-                                            ^
+ required: Test.Bop3[Char]
+  def f4[T](x: Bop3[Char]) = 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
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
 }
diff --git a/test/files/neg/t3692.check b/test/files/neg/t3692.check
index ce89a6563d..96ddd2a461 100644
--- a/test/files/neg/t3692.check
+++ b/test/files/neg/t3692.check
@@ -1,14 +1,4 @@
-t3692.scala:11: warning: type Integer in package scala is deprecated: use <code>java.lang.Integer</code> instead
-      case m0: Map[Int, Int] => new java.util.HashMap[Integer, Integer]
-                                              ^
-t3692.scala:12: warning: type Integer in package scala is deprecated: use <code>java.lang.Integer</code> instead
-      case m1: Map[Int, V] => new java.util.HashMap[Integer, V]
-                                            ^
-t3692.scala:13: warning: type Integer in package scala is deprecated: use <code>java.lang.Integer</code> instead
-      case m2: Map[T, Int] => new java.util.HashMap[T, Integer]
-                                            ^
-t3692.scala:13: error: unreachable code
+t3692.scala:15: error: unreachable code
       case m2: Map[T, Int] => new java.util.HashMap[T, Integer]
                               ^
-three warnings found
 one error found
diff --git a/test/files/neg/t3692.scala b/test/files/neg/t3692.scala
index 78b0e4b843..151535ae94 100644
--- a/test/files/neg/t3692.scala
+++ b/test/files/neg/t3692.scala
@@ -1,3 +1,5 @@
+import java.lang.Integer
+
 object ManifestTester {
   def main(args: Array[String]) = {
     val map = Map("John" -> 1, "Josh" -> 2)
diff --git a/test/files/run/bug2755.check b/test/files/run/bug2755.check
new file mode 100644
index 0000000000..4905c0052d
--- /dev/null
+++ b/test/files/run/bug2755.check
@@ -0,0 +1,21 @@
+1
+2
+3
+4
+5
+6
+7
+1
+2
+3
+4
+5
+6
+7
+1
+2
+3
+4
+5
+6
+7
diff --git a/test/files/run/bug2755.scala b/test/files/run/bug2755.scala
new file mode 100644
index 0000000000..8d10b56734
--- /dev/null
+++ b/test/files/run/bug2755.scala
@@ -0,0 +1,58 @@
+// Test cases: the only place we can cut and paste without crying
+// ourself to sleep.
+object Test {
+  def f1(a: Any)  = a match {
+    case x: Array[Int]      => x(0)
+    case x: Array[Double]   => 2
+    case x: Array[Float]    => x.sum.toInt
+    case x: Array[String]   => x.size
+    case x: Array[AnyRef]   => 5
+    case x: Array[_]        => 6
+    case _                  => 7
+  }
+  def f2(a: Array[_])  = a match {
+    case x: Array[Int]      => x(0)
+    case x: Array[Double]   => 2
+    case x: Array[Float]    => x.sum.toInt
+    case x: Array[String]   => x.size
+    case x: Array[AnyRef]   => 5
+    case x: Array[_]        => 6
+    case _                  => 7
+  }
+  def f3[T](a: Array[T]) = a match {
+    case x: Array[Int]      => x(0)
+    case x: Array[Double]   => 2
+    case x: Array[Float]    => x.sum.toInt
+    case x: Array[String]   => x.size
+    case x: Array[AnyRef]   => 5
+    case x: Array[_]        => 6
+    case _                  => 7
+  }
+
+
+  def main(args: Array[String]): Unit = {
+    println(f1(Array(1, 2, 3)))
+    println(f1(Array(1.0, -2.0, 3.0, 1.0)))
+    println(f1(Array(1.0f, 2.0f, 3.0f, -3.0f)))
+    println(f1((1 to 4).toArray map (_.toString)))
+    println(f1(new Array[Any](10)))    // should match as Array[AnyRef]
+    println(f1(Array(1L)))
+    println(f1(null))
+
+    println(f2(Array(1, 2, 3)))
+    println(f2(Array(1.0, -2.0, 3.0, 1.0)))
+    println(f2(Array(1.0f, 2.0f, 3.0f, -3.0f)))
+    println(f2((1 to 4).toArray map (_.toString)))
+    println(f2(new Array[Any](10)))    // should match as Array[AnyRef]
+    println(f2(Array(1L)))
+    println(f2(null))
+
+    println(f3(Array(1, 2, 3)))
+    println(f3(Array(1.0, -2.0, 3.0, 1.0)))
+    println(f3(Array(1.0f, 2.0f, 3.0f, -3.0f)))
+    println(f3((1 to 4).toArray map (_.toString)))
+    println(f3(new Array[Any](10)))    // should match as Array[AnyRef]
+    println(f3(Array(1L)))
+    println(f3(null))
+  }
+}