Avoid memory leaks on repeated compilation.

Several measures:

1. Invalidate classOfId and superIdOfClass in ContextBase after each run. These contain local classes
   that should become inaccessible.

2. Also clear implicitScope cache that maps types to their implicit scopes after each run. (not sure whether
   this is needed; it did show up in paths from root, but on second thought this might have been a gc-able
   cycle.

3. Avoid capturing contexts in lazy annotations.

4. Avoid capturing contexts in functions that compute souceModule and moduleClass

5. Avoid capturing contexts in Unpickler's postReadOp hook.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/dotty/tools/dotc/core/Contexts.scala b/src/dotty/tools/dotc/core/Contexts.scala
index cfaa3720f..325ff5f74 100644
--- a/src/dotty/tools/dotc/core/Contexts.scala
+++ b/src/dotty/tools/dotc/core/Contexts.scala
@@ -471,6 +471,9 @@ object Contexts {
 
     def reset() = {
       for ((_, set) <- uniqueSets) set.clear()
+      for (i <- 0 until classOfId.length) classOfId(i) = null
+      superIdOfClass.clear()
+      lastSuperId = -1
     }
   }