Avoid some classes of StaleSymbol errors

If a symbol is defined in phases M..N, and that
symbol is then accessed in a phase before M, but in a new run,
we should not issue a stale symbol error (after all, the
symbol is not defined yet). Instead we now return a
NoDenotation.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/Periods.scala b/src/dotty/tools/dotc/core/Periods.scala
index 4ab04fad0..e0d9e3b5d 100644
--- a/src/dotty/tools/dotc/core/Periods.scala
+++ b/src/dotty/tools/dotc/core/Periods.scala
@@ -67,6 +67,8 @@ object Periods {
     /** The first phase of this period */
     def firstPhaseId = lastPhaseId - (code & PhaseMask)
 
+    def containsPhaseId(id: PhaseId) = firstPhaseId <= id && id <= lastPhaseId
+
     /** Does this period contain given period? */
     def contains(that: Period): Boolean = {
       // Let    this = (r1, l1, d1), that = (r2, l2, d2)
@@ -106,6 +108,11 @@ object Periods {
       else
         Nowhere
 
+    def | (that: Period): Period =
+      Period(this.runId,
+          this.firstPhaseId min that.firstPhaseId,
+          this.lastPhaseId max that.lastPhaseId)
+
     override def toString = s"Period($firstPhaseId..$lastPhaseId, run = $runId)"
   }