account for the new BLACKHOLEs in the GHCi debugger

[ghc-hetmet.git] / compiler / ghci / RtClosureInspect.hs

diff --git a/compiler/ghci/RtClosureInspect.hs b/compiler/ghci/RtClosureInspect.hs
index cc16047..e39a0bc 100644 (file)
--- a/compiler/ghci/RtClosureInspect.hs
+++ b/compiler/ghci/RtClosureInspect.hs
@@ -74,7 +74,7 @@ import Data.Ix
 import Data.List
 import qualified Data.Sequence as Seq
 import Data.Monoid
-import Data.Sequence hiding (null, length, index, take, drop, splitAt, reverse)
+import Data.Sequence (viewl, ViewL(..))
 import Foreign
 -- import System.IO.Unsafe
 
@@ -165,7 +165,7 @@ data Closure = Closure { tipe         :: ClosureType
 instance Outputable ClosureType where
   ppr = text . show 
 
-#include "../includes/ClosureTypes.h"
+#include "../includes/rts/storage/ClosureTypes.h"
 
 aP_CODE, pAP_CODE :: Int
 aP_CODE = AP
@@ -654,11 +654,13 @@ cvObtainTerm hsc_env max_depth force old_ty hval = runTR hsc_env $ do
     clos <- trIO $ getClosureData a
     case tipe clos of
 -- Thunks we may want to force
--- NB. this won't attempt to force a BLACKHOLE.  Even with :force, we never
--- force blackholes, because it would almost certainly result in deadlock,
--- and showing the '_' is more useful.
       t | isThunk t && force -> traceTR (text "Forcing a " <> text (show t)) >>
                                 seq a (go (pred max_depth) my_ty old_ty a)
+-- Blackholes are indirections iff the payload is not TSO or BLOCKING_QUEUE.  So we
+-- treat them like indirections; if the payload is TSO or BLOCKING_QUEUE, we'll end up
+-- showing '_' which is what we want.
+      Blackhole -> do traceTR (text "Following a BLACKHOLE")
+                      appArr (go max_depth my_ty old_ty) (ptrs clos) 0
 -- We always follow indirections
       Indirection i -> do traceTR (text "Following an indirection" <> parens (int i) )
                           go max_depth my_ty old_ty $! (ptrs clos ! 0)
@@ -817,6 +819,7 @@ cvReconstructType hsc_env max_depth old_ty hval = runTR_maybe hsc_env $ do
   go my_ty a = do
     clos <- trIO $ getClosureData a
     case tipe clos of
+      Blackhole -> appArr (go my_ty) (ptrs clos) 0 -- carefully, don't eval the TSO
       Indirection _ -> go my_ty $! (ptrs clos ! 0)
       MutVar _ -> do
          contents <- trIO$ IO$ \w -> readMutVar# (unsafeCoerce# a) w