Bringing the tree and icode checkers back to life.

  build/pack/bin/scalac -d /tmp -Ycheck-debug -Ycheck:all \
  src/compiler/scala/tools/nsc/Global.scala

That blows up in constructors as most files do, so also try it with
-Ycheck:icode to see the pretty icode output (for a little while anyway,
after which it will again blow up.)

Our work has only just begun! See test/checker-tests/fail*.scala for
11 examples of places where the checker cries foul. Many of them are
telling us about real issues and we should listen, but I will need help
to figure out which are legitimate and which should be eliminated by
altering the checkers.

This patch also hacks on some territory the checkers drew me into,
especially TypeKinds, where I figured anything which had been commented
out since 2005 was fair game.

(Optional) review by dragos. (The one place I know I could use a look is
in Checkers.scala, because I had to relax some checks and add at least
one newer opcode.)

1 files changed, 145 insertions, 0 deletions

diff --git a/test/checker-tests/fail8.scala b/test/checker-tests/fail8.scala
new file mode 100644
index 0000000000..d64e6e7bcc
--- /dev/null
+++ b/test/checker-tests/fail8.scala
@@ -0,0 +1,145 @@
+// reverse of fail9
+class Ding {
+  private val x1 = 1
+  private def x2 = 2
+  private lazy val x3 = 3
+  private[Ding] val x4 = 4
+  private[Ding] val x5 = 5
+  private[Ding] val x6 = 6
+}
+
+object Ding {
+  def y1 = new Ding x1
+  def y2 = new Ding x2
+  def y3 = new Ding x3
+  def y4 = new Ding x4
+  def y5 = new Ding x5
+  def y6 = new Ding x6
+}
+
+// % work/check all -Xprint:constru work/fail8.scala
+//
+// TypeStack init: REFERENCE(type AnyRef)
+// [Not checkable: parser]
+// [Not checkable: namer]
+// [Not checkable: packageobjects]
+// [Now checking: typer]
+// [Now checking: superaccessors]
+// [Now checking: pickler]
+// [Now checking: refchecks]
+// [Now checking: selectiveanf]
+// [Now checking: liftcode]
+// [Now checking: selectivecps]
+// [Now checking: uncurry]
+// [Now checking: tailcalls]
+// [Not checkable: specialize]
+// [Not checkable: explicitouter]
+// [Now checking: erasure]
+// [Now checking: lazyvals]
+// [Now checking: lambdalift]
+// [[syntax trees at end of constructors]]// Scala source: fail8.scala
+// package <empty> {
+//   class Ding extends java.lang.Object with ScalaObject {
+//     private[this] val Ding$$x1: Int = _;
+//     final <stable> <accessor> def Ding$$x1(): Int = Ding.this.Ding$$x1;
+//     final def Ding$$x2(): Int = 2;
+//     lazy private[this] var Ding$$x3: Int = _;
+//     final <stable> <accessor> lazy def Ding$$x3(): Int = {
+//       Ding.this.Ding$$x3 = 3;
+//       Ding.this.Ding$$x3
+//     };
+//     private[this] val Ding$$x4: Int = _;
+//     <stable> <accessor> private[Ding] def Ding$$x4(): Int = Ding.this.Ding$$x4;
+//     private[this] val Ding$$x5: Int = _;
+//     <stable> <accessor> private[Ding] def Ding$$x5(): Int = Ding.this.Ding$$x5;
+//     private[this] val Ding$$x6: Int = _;
+//     <stable> <accessor> private[Ding] def Ding$$x6(): Int = Ding.this.Ding$$x6;
+//     def this(): Ding = {
+//       Ding.super.this();
+//       Ding.this.Ding$$x1 = 1;
+//       Ding.this.Ding$$x4 = 4;
+//       Ding.this.Ding$$x5 = 5;
+//       Ding.this.Ding$$x6 = 6;
+//       ()
+//     }
+//   };
+//   final class Ding extends java.lang.Object with ScalaObject {
+//     def y1(): Int = new Ding().Ding$$x1();
+//     def y2(): Int = new Ding().Ding$$x2();
+//     def y3(): Int = new Ding().Ding$$x3();
+//     def y4(): Int = new Ding().Ding$$x4();
+//     def y5(): Int = new Ding().Ding$$x5();
+//     def y6(): Int = new Ding().Ding$$x6();
+//     def this(): object Ding = {
+//       Ding.super.this();
+//       ()
+//     }
+//   }
+// }
+//
+// [Now checking: constructors]
+// work/fail8.scala:3: error:
+// **** ERROR DURING INTERNAL CHECKING ****
+// value Ding$$x1 in class Ding cannot be accessed in Ding
+//  because of an internal error (no accessible symbol):
+// sym = value Ding$$x1
+// underlying(sym) = value Ding$$x1
+// pre = Ding
+// site = Ding.this
+// tree = Ding.this.Ding$$x1
+// sym.accessBoundary(sym.owner) = class Ding
+// sym.ownerChain = List(value Ding$$x1, class Ding, package <empty>, package <root>)
+// sym.owner.thisType = Ding
+// context.owner = package <empty>
+// context.outer.enclClass.owner = package <empty>
+//   private val x1 = 1
+//               ^
+// work/fail8.scala:6: error:
+// **** ERROR DURING INTERNAL CHECKING ****
+// value Ding$$x4 in class Ding cannot be accessed in Ding
+//  because of an internal error (no accessible symbol):
+// sym = value Ding$$x4
+// underlying(sym) = value Ding$$x4
+// pre = Ding
+// site = Ding.this
+// tree = Ding.this.Ding$$x4
+// sym.accessBoundary(sym.owner) = class Ding
+// sym.ownerChain = List(value Ding$$x4, class Ding, package <empty>, package <root>)
+// sym.owner.thisType = Ding
+// context.owner = package <empty>
+// context.outer.enclClass.owner = package <empty>
+//   private[Ding] val x4 = 4
+//                     ^
+// work/fail8.scala:7: error:
+// **** ERROR DURING INTERNAL CHECKING ****
+// value Ding$$x5 in class Ding cannot be accessed in Ding
+//  because of an internal error (no accessible symbol):
+// sym = value Ding$$x5
+// underlying(sym) = value Ding$$x5
+// pre = Ding
+// site = Ding.this
+// tree = Ding.this.Ding$$x5
+// sym.accessBoundary(sym.owner) = class Ding
+// sym.ownerChain = List(value Ding$$x5, class Ding, package <empty>, package <root>)
+// sym.owner.thisType = Ding
+// context.owner = package <empty>
+// context.outer.enclClass.owner = package <empty>
+//   private[Ding] val x5 = 5
+//                     ^
+// work/fail8.scala:8: error:
+// **** ERROR DURING INTERNAL CHECKING ****
+// value Ding$$x6 in class Ding cannot be accessed in Ding
+//  because of an internal error (no accessible symbol):
+// sym = value Ding$$x6
+// underlying(sym) = value Ding$$x6
+// pre = Ding
+// site = Ding.this
+// tree = Ding.this.Ding$$x6
+// sym.accessBoundary(sym.owner) = class Ding
+// sym.ownerChain = List(value Ding$$x6, class Ding, package <empty>, package <root>)
+// sym.owner.thisType = Ding
+// context.owner = package <empty>
+// context.outer.enclClass.owner = package <empty>
+//   private[Ding] val x6 = 6
+//                     ^
+// four errors found