lib: note a problem with dbg*IO

2016-12-07 07:52:10 -08:00 · 2016-12-07 07:52:10 -08:00 · 00e2a8a327
commit 00e2a8a327
parent 2e8e67aa09
1 changed files with 3 additions and 0 deletions
--- a/hledger-lib/Hledger/Utils/Debug.hs
+++ b/hledger-lib/Hledger/Utils/Debug.hs
@ -117,6 +117,9 @@ dbg9 = tracePrettyAt 9

 -- | Convenience aliases for tracePrettyAtIO.
 -- Like dbg, but convenient to insert in an IO monad.
+-- XXX These have a bug; they should use traceIO, not trace,
+-- otherwise GHC can occasionally over-optimise
+-- (cf lpaste a few days ago where it killed/blocked a child thread).
 dbg0IO :: (MonadIO m, Show a) => String -> a -> m ()
 dbg0IO = tracePrettyAtIO 0