Added a migration warning for matches and insta...

Added a migration warning for matches and instance tests when it might
be an Array/Seq test whose answer has changed. Review by odersky.

3 files changed, 43 insertions, 0 deletions

diff --git a/test/files/neg/array-not-seq.check b/test/files/neg/array-not-seq.check
new file mode 100644
index 0000000000..bd72bb4e13
--- /dev/null
+++ b/test/files/neg/array-not-seq.check
@@ -0,0 +1,16 @@
+array-not-seq.scala:2: error: An Array will no longer match as Seq[_].
+  def f1(x: Any) = x.isInstanceOf[Seq[_]]
+                                 ^
+array-not-seq.scala:4: error: An Array will no longer match as Seq[_].
+    case _: Seq[_]  => true
+          ^
+error: An Array will no longer match as Seq[_].
+array-not-seq.scala:16: error: An Array will no longer match as Seq[_].
+    case (Some(_: Seq[_]), Nil, _)        => 1
+                ^
+error: An Array will no longer match as Seq[_].
+array-not-seq.scala:15: error: An Array will no longer match as Seq[_].
+  def f5(x1: Any, x2: Any, x3: AnyRef) = (x1, x2, x3) match {
+                                              ^
+error: An Array will no longer match as Seq[_].
+7 errors found
diff --git a/test/files/neg/array-not-seq.flags b/test/files/neg/array-not-seq.flags
new file mode 100644
index 0000000000..4e9f7e4a56
--- /dev/null
+++ b/test/files/neg/array-not-seq.flags
@@ -0,0 +1 @@
+-Xmigration -Xfatal-warnings
\ No newline at end of file
diff --git a/test/files/neg/array-not-seq.scala b/test/files/neg/array-not-seq.scala
new file mode 100644
index 0000000000..07a2898d88
--- /dev/null
+++ b/test/files/neg/array-not-seq.scala
@@ -0,0 +1,26 @@
+object Test {
+  def f1(x: Any) = x.isInstanceOf[Seq[_]]
+  def f2(x: Any) = x match {
+    case _: Seq[_]  => true
+    case _          => false
+  }
+
+  def f3(x: Any) = x match {
+    case _: Array[_]  => true
+    case _            => false
+  }
+
+  def f4(x: Any) = x.isInstanceOf[Traversable[_]]
+
+  def f5(x1: Any, x2: Any, x3: AnyRef) = (x1, x2, x3) match {
+    case (Some(_: Seq[_]), Nil, _)        => 1
+    case (None, List(_: List[_], _), _)   => 2
+    case _                                => 3
+  }
+
+  def main(args: Array[String]): Unit = {
+    // println(f1(Array(1)))
+    // println(f2(Array(1)))
+    // println(f3(Array(1))
+  }
+}