TailRec phase and tests for it.

Ported tailcall phase from scalac with such changes:
  - all transformation is done in the phase itself
     (previously half of the work was done in backend)
  - it is now able to run before uncurry
  - it is now a treeTransform
  - renamed to tailrec to make it more obvious that
     this phase transforms only recursive calls.

For now this is a single phase which speculatively
transforms DefDefs.
Speculation can be potentially removed by
splitting into 2 phases:
  one detecting which methods should be transformed
  second performing transformation.

But, as transformation requires as same amount of work
as detection, I believe it will be simpler to maintain
it as a single phase.

Conflicts:
	tests/pos/typers.scala

7 files changed, 0 insertions, 119 deletions

diff --git a/tests/untried/pos/t1672.scala b/tests/untried/pos/t1672.scala
deleted file mode 100644
index 5ee6bb175..000000000
--- a/tests/untried/pos/t1672.scala
+++ /dev/null
@@ -1,10 +0,0 @@
-object Test {
-  @annotation.tailrec
-  def bar : Nothing = {
-    try {
-      throw new RuntimeException
-    } catch {
-      case _: Throwable => bar
-    }
-  }
-}
diff --git a/tests/untried/pos/t4649.flags b/tests/untried/pos/t4649.flags
deleted file mode 100644
index e8fb65d50..000000000
--- a/tests/untried/pos/t4649.flags
+++ /dev/null
@@ -1 +0,0 @@
--Xfatal-warnings
\ No newline at end of file
diff --git a/tests/untried/pos/t4649.scala b/tests/untried/pos/t4649.scala
deleted file mode 100644
index 0d6caa8d7..000000000
--- a/tests/untried/pos/t4649.scala
+++ /dev/null
@@ -1,6 +0,0 @@
-object Test {
-  // @annotation.tailrec
-  def lazyFilter[E](s: Stream[E], p: E => Boolean): Stream[E] = s match {
-    case h #:: t => if (p(h)) h #:: lazyFilter(t, p) else lazyFilter(t, p)
-  }
-}
diff --git a/tests/untried/pos/t6479.scala b/tests/untried/pos/t6479.scala
deleted file mode 100644
index e4a4ff601..000000000
--- a/tests/untried/pos/t6479.scala
+++ /dev/null
@@ -1,56 +0,0 @@
-object TailrecAfterTryCatch {
-
-  @annotation.tailrec
-  final def good1(): Unit = {
-    1 match {
-      case 2 => {
-        try {
-        //  return
-        } catch {
-          case e: ClassNotFoundException =>
-        }
-        good1()
-      }
-    }
-  }
-
-  @annotation.tailrec
-  final def good2(): Unit = {
-    //1 match {
-    //  case 2 => {
-        try {
-          return
-        } catch {
-          case e: ClassNotFoundException =>
-        }
-        good2()
-    //  }
-    //}
-  }
-
-  @annotation.tailrec
-  final def good3(): Unit = {
-    val 1 = 2
-    try {
-      return
-    } catch {
-      case e: ClassNotFoundException =>
-    }
-    good3()
-  }
-
-  @annotation.tailrec
-  final def bad(): Unit = {
-    1 match {
-      case 2 => {
-        try {
-          return
-        } catch {
-          case e: ClassNotFoundException =>
-        }
-        bad()
-      }
-    }
-  }
-
-}
diff --git a/tests/untried/pos/t6574.scala b/tests/untried/pos/t6574.scala
deleted file mode 100644
index 6bb0042c6..000000000
--- a/tests/untried/pos/t6574.scala
+++ /dev/null
@@ -1,19 +0,0 @@
-class Bad[X, Y](val v: Int) extends AnyVal {
-  def vv = v
-  @annotation.tailrec final def foo[Z](a: Int)(b: String): Unit = {
-    this.foo[Z](a)(b)
-  }
-
-  @annotation.tailrec final def differentReceiver {: Unit = 
-    {(); new Bad[X, Y](0)}.differentReceiver
-  }
-
-  @annotation.tailrec final def dependent[Z](a: Int)(b: String): b.type = {
-    this.dependent[Z](a)(b)
-  }
-}
-
-class HK[M[_]](val v: Int) extends AnyVal {
-  def hk[N[_]]: Unit = if (false) hk[M] else ()
-}
-
diff --git a/tests/untried/pos/t6891.flags b/tests/untried/pos/t6891.flags
deleted file mode 100644
index fe048006a..000000000
--- a/tests/untried/pos/t6891.flags
+++ /dev/null
@@ -1 +0,0 @@
--Ycheck:extmethods -Xfatal-warnings
\ No newline at end of file
diff --git a/tests/untried/pos/t6891.scala b/tests/untried/pos/t6891.scala
deleted file mode 100644
index bed2d0d77..000000000
--- a/tests/untried/pos/t6891.scala
+++ /dev/null
@@ -1,26 +0,0 @@
-object O {
-  implicit class Foo[A](val value: String) extends AnyVal {
-    def bippy() = {
-      @annotation.tailrec def loop(x: A): Unit = loop(x)
-      ()
-    }
-
-    def boppy() = {
-      @annotation.tailrec def loop(x: value.type): Unit = loop(x)
-      ()
-    }
-
-    def beppy[C](c: => C) = {
-      () => c
-      @annotation.tailrec def loop(x: value.type): Unit = loop(x)
-        () => c
-      ()
-    }
-  }
-  // uncaught exception during compilation: Types$TypeError("type mismatch;
-  //  found   : A(in method bippy$extension)
-  //  required: A(in class Foo)") @ scala.tools.nsc.typechecker.Contexts$Context.issueCommon(Contexts.scala:396)
-  // error: scala.reflect.internal.Types$TypeError: type mismatch;
-  //  found   : A(in method bippy$extension)
-  //  required: A(in class Foo)
-}