Merge pull request #4341 from retronym/ticket/9157

SI-9157 Avoid exponential blowup with chained type projections

2 files changed, 5 insertions, 6 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
index 743bbe53bd..02356580cc 100644
--- a/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/TreeCheckers.scala
@@ -266,7 +266,6 @@ abstract class TreeCheckers extends Analyzer {
 
       if (tree ne typed)
         treesDiffer(tree, typed)
-
       tree
     }
 
diff --git a/src/reflect/scala/reflect/internal/Types.scala b/src/reflect/scala/reflect/internal/Types.scala
index ce36f7efa3..8f114caac0 100644
--- a/src/reflect/scala/reflect/internal/Types.scala
+++ b/src/reflect/scala/reflect/internal/Types.scala
@@ -1976,13 +1976,13 @@ trait Types
      * usage scenario.
      */
     private var relativeInfoCache: Type = _
-    private var memberInfoCache: Type = _
+    private var relativeInfoPeriod: Period = NoPeriod
 
-    private[Types] def relativeInfo = {
-      val memberInfo = pre.memberInfo(sym)
-      if (relativeInfoCache == null || (memberInfo ne memberInfoCache)) {
-        memberInfoCache = memberInfo
+    private[Types] def relativeInfo = /*trace(s"relativeInfo(${safeToString}})")*/{
+      if (relativeInfoPeriod != currentPeriod) {
+        val memberInfo = pre.memberInfo(sym)
         relativeInfoCache = transformInfo(memberInfo)
+        relativeInfoPeriod = currentPeriod
       }
       relativeInfoCache
     }