Properly ppr InstEqs in wanteds of implication constraints

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

diff --git a/compiler/specialise/SpecConstr.lhs b/compiler/specialise/SpecConstr.lhs
index 48718af..0478d2e 100644 (file)
--- a/compiler/specialise/SpecConstr.lhs
+++ b/compiler/specialise/SpecConstr.lhs
@@ -4,6 +4,13 @@
 \section[SpecConstr]{Specialise over constructors}
 
 \begin{code}
+{-# OPTIONS -w #-}
+-- The above warning supression flag is a temporary kludge.
+-- While working on this module you are encouraged to remove it and fix
+-- any warnings in the module. See
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
+-- for details
+
 module SpecConstr(
        specConstrProgram       
     ) where
@@ -20,11 +27,11 @@ import CoreTidy             ( tidyRules )
 import PprCore         ( pprRules )
 import WwLib           ( mkWorkerArgs )
 import DataCon         ( dataConRepArity, dataConUnivTyVars )
-import Type            ( Type, tyConAppArgs )
-import Coercion                ( coercionKind )
+import Coercion        
+import Type            hiding( substTy )
 import Id              ( Id, idName, idType, isDataConWorkId_maybe, idArity,
                          mkUserLocal, mkSysLocal, idUnfolding, isLocalId )
-import Var             ( Var )
+import Var
 import VarEnv
 import VarSet
 import Name
@@ -1100,10 +1107,15 @@ argToPat in_scope val_env (Let _ arg) arg_occ
 
 argToPat in_scope val_env (Cast arg co) arg_occ
   = do { (interesting, arg') <- argToPat in_scope val_env arg arg_occ
-       ; if interesting then 
-               return (interesting, Cast arg' co)
-         else 
-               wildCardPat (snd (coercionKind co)) }
+       ; let (ty1,ty2) = coercionKind co
+       ; if not interesting then 
+               wildCardPat ty2
+         else do
+       { -- Make a wild-card pattern for the coercion
+         uniq <- getUniqueUs
+       ; let co_name = mkSysTvName uniq FSLIT("sg")
+             co_var = mkCoVar co_name (mkCoKind ty1 ty2)
+       ; return (interesting, Cast arg' (mkTyVarTy co_var)) } }
 
 {-     Disabling lambda specialisation for now
        It's fragile, and the spec_loop can be infinite
@@ -1242,12 +1254,10 @@ samePat (vs1, as1) (vs2, as2)
 
     same e1 e2 = WARN( bad e1 || bad e2, ppr e1 $$ ppr e2) 
                 False  -- Let, lambda, case should not occur
-#ifdef DEBUG
     bad (Case {}) = True
     bad (Let {})  = True
     bad (Lam {})  = True
     bad other    = False
-#endif
 \end{code}
 
 Note [Ignore type differences]