Fix the infinite cycle in Lazy Vlas

DarkDimius · nicolasstucki · commit 5709485cf32c · 2018-03-21T11:18:51.000+01:00
Reported by Andrzej Plutecki in https://groups.google.com/forum/#!topic/dotty-internals/3LMNItLQw-A I haven't seen this happen in practice in hours and hours of benchmarking, but this is indeed a formal bug.
diff --git a/library/src/dotty/runtime/LazyVals.scala b/library/src/dotty/runtime/LazyVals.scala
@@ -67,7 +67,8 @@ object LazyVals {
       else if (state == 2) {
         val monitor = getMonitor(t, ord)
         monitor.synchronized {
-          monitor.wait()
+          if (STATE(cur, ord) == 2)
+            monitor.wait()
         }
       }
       else retry = false

Original file line number	Diff line number	Diff line change
`@@ -67,7 +67,8 @@ object LazyVals {`
`67`	`67`	`else if (state == 2) {`
`68`	`68`	`val monitor = getMonitor(t, ord)`
`69`	`69`	`monitor.synchronized {`
`70`		`- monitor.wait()`
	`70`	`+ if (STATE(cur, ord) == 2)`
	`71`	`+ monitor.wait()`
`71`	`72`	`}`
`72`	`73`	`}`
`73`	`74`	`else retry = false`