Avoid cyclic errors when reading nsc.Global

With the change in the next commit this addition is needed
to make i859.scala compile. Previously the same effect was
achieved accidentally by `updateTypeParams`. The comment
admits that we do not really know why the functionality is needed.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
index 239dd4124..2ea911380 100644
--- a/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
+++ b/src/dotty/tools/dotc/core/unpickleScala2/Scala2Unpickler.scala
@@ -135,6 +135,13 @@ object Scala2Unpickler {
     denot.info = ClassInfo( // final info, except possibly for typeparams ordering
       denot.owner.thisType, denot.classSymbol, parentRefs, decls, ost)
     denot.updateTypeParams(tparams)
+
+    // Curiously the following line is needed to make pos/i859.scala compile.
+    // This test simply accesses scala.tools.nsc.Global. I could not track down why
+    // the reference is needed - referencing any field of the type parameter
+    // does the trick, no completion is needed (in fact such completion would
+    // cause cyclic references elsewhere).
+    assert(denot.typeParams.forall(_.exists))
   }
 }