[project @ 1998-04-10 15:00:19 by simonpj]

[ghc-hetmet.git] / ghc / compiler / specialise / Specialise.lhs

diff --git a/ghc/compiler/specialise/Specialise.lhs b/ghc/compiler/specialise/Specialise.lhs
index e550294..6041340 100644 (file)
--- a/ghc/compiler/specialise/Specialise.lhs
+++ b/ghc/compiler/specialise/Specialise.lhs
@@ -721,7 +721,13 @@ specBind (NonRec bndr rhs) body_uds
     specDefn (calls body_uds) (bndr,rhs)       `thenSM` \ ((bndr',rhs'), spec_defns, spec_uds) ->
     let
        (all_uds, (dict_binds, dump_calls)) 
-               = splitUDs [ValBinder bndr] (spec_uds `plusUDs` body_uds)
+               = splitUDs [ValBinder bndr]
+                          (body_uds `plusUDs` spec_uds)
+                       -- It's important that the `plusUDs` is this way round,
+                       -- because body_uds may bind dictionaries that are
+                       -- used in the calls passed to specDefn.  So the
+                       -- dictionary bindings in spec_uds may mention 
+                       -- dictionaries bound in body_uds.
 
         -- If we make specialisations then we Rec the whole lot together
         -- If not, leave it as a NonRec
@@ -736,8 +742,12 @@ specBind (Rec pairs) body_uds
        (pairs', spec_defns_s, spec_uds_s) = unzip3 stuff
        spec_defns = concat spec_defns_s
        spec_uds   = plusUDList spec_uds_s
+
        (all_uds, (dict_binds, dump_calls)) 
-               = splitUDs (map (ValBinder . fst) pairs) (spec_uds `plusUDs` body_uds)
+               = splitUDs (map (ValBinder . fst) pairs)
+                          (body_uds `plusUDs` spec_uds)
+                       -- See notes for non-rec case
+
         new_bind = Rec (spec_defns ++ pairs')
     in
     returnSM ( new_bind : mkDictBinds dict_binds, all_uds )