Fix type signature to work without -XRelaxedPolyRec, and hence earlier GHCs

diff --git a/compiler/cmm/ZipDataflow.hs b/compiler/cmm/ZipDataflow.hs
index bcddd8e..60bcda7 100644 (file)
--- a/compiler/cmm/ZipDataflow.hs
+++ b/compiler/cmm/ZipDataflow.hs
@@ -650,7 +650,7 @@ backward_sol check_maybe return_graph = back
             }
    in fixed_point
 
-bwd_pure_anal :: (DebugNodes m l, Outputable a)
+bwd_pure_anal :: (DebugNodes m l, LastNode l, Outputable a)
              => PassName
              -> BlockEnv a
              -> BackwardTransfers m l a