X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FInstEnv.lhs;h=8fd3d8324495e5771d2a53b58b39cd2e9994ce65;hb=288213d7c2c65fa68ca466c1a1a3378e24fa1151;hp=560c4fc24be1464a8e0c1835138cc92fbd0b0a7b;hpb=940524aec90652b5ef81789c9a453c57c0e42cc9;p=ghc-hetmet.git

diff --git a/compiler/types/InstEnv.lhs b/compiler/types/InstEnv.lhs
index 560c4fc..8fd3d83 100644
--- a/compiler/types/InstEnv.lhs
+++ b/compiler/types/InstEnv.lhs
@@ -33,7 +33,6 @@ import Outputable
 import BasicTypes
 import UniqFM
 import Id
-import SrcLoc
 
 import Data.Maybe	( isJust, isNothing )
 \end{code}
@@ -132,9 +131,9 @@ instance Outputable Instance where
 
 pprInstance :: Instance -> SDoc
 -- Prints the Instance as an instance declaration
-pprInstance ispec@(Instance { is_flag = flag })
+pprInstance ispec
   = hang (pprInstanceHdr ispec)
-	2 (ptext SLIT("--") <+> (pprDefnLoc (getSrcSpan ispec)))
+	2 (ptext SLIT("--") <+> pprNameLoc (getName ispec))
 
 -- * pprInstanceHdr is used in VStudio to populate the ClassView tree
 pprInstanceHdr :: Instance -> SDoc
@@ -184,7 +183,7 @@ instanceCantMatch :: [Maybe Name] -> [Maybe Name] -> Bool
 -- possibly be instantiated to actual, nor vice versa; 
 -- False is non-committal
 instanceCantMatch (Just t : ts) (Just a : as) = t/=a || instanceCantMatch ts as
-instanceCantMatch ts		as	      =  False	-- Safe
+instanceCantMatch _             _             =  False  -- Safe
 \end{code}
 
 
@@ -371,7 +370,7 @@ extendInstEnv inst_env ins_item@(Instance { is_cls = cls_nm, is_tcs = mb_tcs })
     add (ClsIE cur_insts cur_tyvar) _ = ClsIE (ins_item : cur_insts)
 					      (ins_tyvar || cur_tyvar)
     ins_tyvar = not (any isJust mb_tcs)
-\end{code}		      
+\end{code}
 
 
 %************************************************************************
@@ -430,10 +429,11 @@ lookupInstEnv (pkg_ie, home_ie) cls tys
     (pkg_matches,  pkg_unifs)  = lookup pkg_ie  
     all_matches = home_matches ++ pkg_matches
     all_unifs   = home_unifs   ++ pkg_unifs
-    pruned_matches 
-	| null all_unifs = foldr insert_overlapping [] all_matches
-	| otherwise	 = all_matches	-- Non-empty unifs is always an error situation,
-					-- so don't attempt to pune the matches
+    pruned_matches = foldr insert_overlapping [] all_matches
+	-- Even if the unifs is non-empty (an error situation)
+	-- we still prune the matches, so that the error message isn't
+	-- misleading (complaining of multiple matches when some should be
+	-- overlapped away)
 
     --------------
     lookup env = case lookupUFM env cls of
@@ -483,9 +483,10 @@ lookupInstEnv (pkg_ie, home_ie) cls tys
 		-- They shouldn't because we allocate separate uniques for them
         case tcUnifyTys bind_fn tpl_tys tys of
 	    Just _   -> find ms (item:us) rest
-	    Nothing  -> find ms us	   rest
+	    Nothing  -> find ms us	  rest
 
 ---------------
+bind_fn :: TyVar -> BindFlag
 bind_fn tv | isTcTyVar tv && isExistentialTyVar tv = Skolem
 	   | otherwise	 		 	   = BindMe
 	-- The key_tys can contain skolem constants, and we can guarantee that those
@@ -531,6 +532,6 @@ insert_overlapping new_item (item:items)
 	where
 	  overlap_ok = case is_flag instB of
 			NoOverlap -> False
-			other	  -> True
+			_         -> True
 \end{code}