Properly ppr InstEqs in wanteds of implication constraints

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

diff --git a/compiler/specialise/Rules.lhs b/compiler/specialise/Rules.lhs
index 26a499b..24c4004 100644 (file)
--- a/compiler/specialise/Rules.lhs
+++ b/compiler/specialise/Rules.lhs
@@ -4,6 +4,13 @@
 \section[CoreRules]{Transformation rules}
 
 \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 Rules (
        RuleBase, emptyRuleBase, mkRuleBase, extendRuleBaseList, 
        unionRuleBase, pprRuleBase, ruleCheckProgram,
@@ -588,11 +595,8 @@ match menv subst (Type ty1) (Type ty2)
   = match_ty menv subst ty1 ty2
 
 match menv subst (Cast e1 co1) (Cast e2 co2)
-  | (from1, to1) <- coercionKind co1
-  , (from2, to2) <- coercionKind co2
-  = do { subst1 <- match_ty menv subst  to1   to2
-       ; subst2 <- match_ty menv subst1 from1 from2
-       ; match menv subst2 e1 e2 }
+  = do { subst1 <- match_ty menv subst co1 co2
+       ; match menv subst1 e1 e2 }
 
 {-     REMOVING OLD CODE: I think that the above handling for let is 
                           better than the stuff here, which looks 
@@ -639,6 +643,8 @@ match_var menv subst@(tv_subst, id_subst, binds) v1 e2
 
                | otherwise     -- No renaming to do on e2, because no free var
                                -- of e2 is in the rnEnvR of the envt
+               -- Note [Matching variable types]
+               -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
                -- However, we must match the *types*; e.g.
                --   forall (c::Char->Int) (x::Char). 
                --      f (c x) = "RULE FIRED"