X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcTyFuns.lhs;h=0130aa6c4ebd984cff9d64ebfb7e48f10a2179ea;hb=eeb635d0ed2346568e312ac06ce7f2f1ecb434be;hp=b5ceb78abb139fcb8b08a78ace7c74f7ad6fbd2c;hpb=17b297d97d327620ed6bfab942f8992b2446f1bf;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcTyFuns.lhs b/compiler/typecheck/TcTyFuns.lhs
index b5ceb78..0130aa6 100644
--- a/compiler/typecheck/TcTyFuns.lhs
+++ b/compiler/typecheck/TcTyFuns.lhs
@@ -1,10 +1,10 @@
 
 \begin{code}
-{-# OPTIONS_GHC -w #-}
+{-# 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/WorkingConventions#Warnings
+--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
 -- for details
 
 module TcTyFuns(
@@ -576,7 +576,7 @@ decompInst i@(EqInst {})
                         do { cotvs <- zipWithM (\t1 t2 -> 
                                                 newMetaTyVar TauTv 
                                                              (mkCoKind t1 t2)) 
-                                               tys1' tys2'
+                                               tys1 tys2
                            ; let cos = map TyVarTy cotvs
                            ; writeMetaTyVar old_covar (TyConApp con1 cos)
                            ; return $ map mkWantedCo cotvs
@@ -584,17 +584,19 @@ decompInst i@(EqInst {})
                       -- co_i := Con_i old_co
                       (\old_co -> return $ 
                                     map mkGivenCo $
-                                        mkRightCoercions (length tys1') old_co)
-           ; insts <- zipWithM mkEqInst (zipWith EqPred tys1' tys2') cos
-           ; return (insts, not $ null insts)
+                                        mkRightCoercions (length tys1) old_co)
+           ; insts <- zipWithM mkEqInst (zipWith EqPred tys1 tys2) cos
+           ; traceTc (text "decomp identicalHead" <+> ppr insts) 
+           ; return (insts, not $ null insts) 
            }
       | con1 /= con2 && not (isOpenSynTyCon con1 || isOpenSynTyCon con2)
         -- not matching data constructors (of any flavour) are bad news
       = do { env0 <- tcInitTidyEnv
-           ; let (env1, tidy_ty1)  =  tidyOpenType env0 ty1
-                 (env2, tidy_ty2)  =  tidyOpenType env1 ty2
-                 extra 	         = sep [ppr tidy_ty1, char '~', ppr tidy_ty2]
-                 msg 		 = ptext SLIT("Couldn't match expected type against inferred type")
+           ; let (env1, tidy_ty1) = tidyOpenType env0 ty1
+                 (env2, tidy_ty2) = tidyOpenType env1 ty2
+                 extra 	          = sep [ppr tidy_ty1, char '~', ppr tidy_ty2]
+                 msg 		  = 
+                   ptext SLIT("Unsolvable equality constraint:")
            ; failWithTcM (env2, hang msg 2 extra)
            }
       where