X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FFamInst.lhs;h=e2da7952a92291d4cd6d8e1f7faa7a6650b218e3;hp=5f4b2a3f922a38ac76a0c12c0ecd822b89091320;hb=d2ce0f52d42edf32bb9f13796e6ba6edba8bd516;hpb=0f66260b5afc88accb6af6a09b20c3a4de51c39a

diff --git a/compiler/typecheck/FamInst.lhs b/compiler/typecheck/FamInst.lhs
index 5f4b2a3..e2da795 100644
--- a/compiler/typecheck/FamInst.lhs
+++ b/compiler/typecheck/FamInst.lhs
@@ -2,7 +2,7 @@ The @FamInst@ type: family instance heads
 
 \begin{code}
 module FamInst ( 
-        checkFamInstConsistency, tcExtendLocalFamInstEnv
+        checkFamInstConsistency, tcExtendLocalFamInstEnv, tcGetFamInstEnvs
     ) where
 
 import HscTypes
@@ -11,17 +11,16 @@ import TcMType
 import TcType
 import TcRnMonad
 import TyCon
-import Type
 import Name
 import Module
 import SrcLoc
 import Outputable
-import LazyUniqFM
+import UniqFM
 import FiniteMap
 import FastString
 
 import Maybes
-import Monad
+import Control.Monad
 \end{code}
 
 
@@ -178,38 +177,14 @@ checkForConflicts inst_envs famInst
 		-- (since we do unification).  
 		-- We use tcInstSkolType because we don't want to allocate
 		-- fresh *meta* type variables.  
-       ; let { tycon = famInstTyCon famInst
-	     ; ty    = case tyConFamInst_maybe tycon of
-		         Nothing        -> panic "FamInst.checkForConflicts"
-		         Just (tc, tys) -> tc `mkTyConApp` tys
-             }
-       ; (_, _, tau') <- tcInstSkolType FamInstSkol ty
-
-       ; let (fam, tys') = tcSplitTyConApp tau'
-
-       ; let { matches   = lookupFamInstEnvUnify inst_envs fam tys'
-	     ; conflicts = [ conflictingFamInst
-			   | match@((conflictingFamInst, _), _) <- matches
-			   , conflicting tycon match 
-			   ]
-	     }
+
+       ; skol_tvs <- tcInstSkolTyVars FamInstSkol 
+                                      (tyConTyVars (famInstTyCon famInst))
+       ; let conflicts = lookupFamInstEnvConflicts inst_envs famInst skol_tvs
        ; unless (null conflicts) $
-	   conflictInstErr famInst (head conflicts)
+	   conflictInstErr famInst (fst (head conflicts))
        }
   where
-      -- - In the case of data family instances, any overlap is fundamentally a
-      --   conflict (as these instances imply injective type mappings).
-      -- - In the case of type family instances, overlap is admitted as long as
-      --   the right-hand sides of the overlapping rules coincide under the
-      --   overlap substitution.  We require that they are syntactically equal;
-      --   anything else would be difficult to test for at this stage.
-    conflicting tycon1 ((famInst2, _), subst) 
-      | isAlgTyCon tycon1 = True
-      | otherwise         = not (rhs1 `tcEqType` rhs2)
-      where
-        tycon2 = famInstTyCon famInst2
-        rhs1   = substTy subst $ synTyConType tycon1
-        rhs2   = substTy subst $ synTyConType tycon2
 
 conflictInstErr :: FamInst -> FamInst -> TcRn ()
 conflictInstErr famInst conflictingFamInst
@@ -222,4 +197,17 @@ addFamInstLoc famInst thing_inside
   = setSrcSpan (mkSrcSpan loc loc) thing_inside
   where
     loc = getSrcLoc famInst
+\end{code} 
+
+\begin{code} 
+
+tcGetFamInstEnvs :: TcM (FamInstEnv, FamInstEnv)
+-- Gets both the external-package inst-env
+-- and the home-pkg inst env (includes module being compiled)
+tcGetFamInstEnvs 
+  = do { eps <- getEps; env <- getGblEnv
+       ; return (eps_fam_inst_env eps, tcg_fam_inst_env env) 
+       }
+
+
 \end{code}