X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcInstDcls.lhs;h=d4d8d2fbc543e6133eee500eb3955fdcca77a9e6;hp=c2e9bc8921c338c52aa8ffd7a8ac6d68c84a2714;hb=792449f555bb4dfa8e718079f6d42dc9babe938a;hpb=d7fb8d371d3228774331a67db8da805b2d68f1c4

diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs
index c2e9bc8..d4d8d2f 100644
--- a/compiler/typecheck/TcInstDcls.lhs
+++ b/compiler/typecheck/TcInstDcls.lhs
@@ -665,7 +665,6 @@ tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
 
          -- (2) type check indexed data type declaration
        ; tcTyVarBndrs k_tvs $ \t_tvs -> do {  -- turn kinded into proper tyvars
-       ; unbox_strict <- doptM Opt_UnboxStrictFields
 
          -- kind check the type indexes and the context
        ; t_typats     <- mapM tcHsKindedType k_typats
@@ -684,7 +683,7 @@ tcFamInstDecl1 (decl@TyData {tcdND = new_or_data, tcdLName = L loc tc_name,
        ; let ex_ok = True	-- Existentials ok for type families!
        ; fixM (\ rep_tycon -> do 
 	     { let orig_res_ty = mkTyConApp fam_tycon t_typats
-	     ; data_cons <- tcConDecls unbox_strict ex_ok rep_tycon
+	     ; data_cons <- tcConDecls ex_ok rep_tycon
 				       (t_tvs, orig_res_ty) k_cons
 	     ; tc_rhs <-
 		 case new_or_data of
@@ -795,6 +794,9 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = ibinds })
     addErrCtxt (instDeclCtxt2 (idType dfun_id)) $ 
     do {  -- Instantiate the instance decl with skolem constants
        ; (inst_tyvars, dfun_theta, inst_head) <- tcSkolDFunType (idType dfun_id)
+                     -- We instantiate the dfun_id with superSkolems.
+                     -- See Note [Subtle interaction of recursion and overlap]
+                     -- and Note [Binding when looking up instances]
        ; let (clas, inst_tys) = tcSplitDFunHead inst_head
              (class_tyvars, sc_theta, _, op_items) = classBigSig clas
              sc_theta' = substTheta (zipOpenTvSubst class_tyvars inst_tys) sc_theta
@@ -873,7 +875,7 @@ tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = ibinds })
                  listToBag meth_binds)
        }
  where
-   skol_info = InstSkol         -- See Note [Subtle interaction of recursion and overlap]
+   skol_info = InstSkol         
    dfun_ty   = idType dfun_id
    dfun_id   = instanceDFunId ispec
    loc       = getSrcSpan dfun_id