Catch stale references

If a NamedType was denoted a SymDenotation one run, but stops being defined in the next, throw a staleSymbol error.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/dotty/tools/dotc/core/Denotations.scala b/src/dotty/tools/dotc/core/Denotations.scala
index e6d5023e5..90a6a373c 100644
--- a/src/dotty/tools/dotc/core/Denotations.scala
+++ b/src/dotty/tools/dotc/core/Denotations.scala
@@ -479,7 +479,7 @@ object Denotations {
           } while (d ne denot)
           initial.copyIfParentInvalid
         case _ =>
-          throw new Error(s"stale symbol; $this, defined in run ${valid.runId} is referred to in run ${currentPeriod.runId}")
+          staleSymbolError
       }
       if (valid.runId != currentPeriod.runId) bringForward.current
       else {
@@ -523,6 +523,9 @@ object Denotations {
       }
     }
 
+    def staleSymbolError(implicit ctx: Context) =
+      throw new Error(s"stale symbol; $this, defined in run ${myValidFor.runId} is referred to in run ${ctx.period.runId}")
+
     /** For ClassDenotations only:
      *  If caches influenced by parent classes are still valid, the denotation
      *  itself, otherwise a freshly initialized copy.