Adapt mkGenericDefMethBind to the new generics

[ghc-hetmet.git] / compiler / typecheck / TcClassDcl.lhs

diff --git a/compiler/typecheck/TcClassDcl.lhs b/compiler/typecheck/TcClassDcl.lhs
index 62a3da8..36bef11 100644 (file)
--- a/compiler/typecheck/TcClassDcl.lhs
+++ b/compiler/typecheck/TcClassDcl.lhs
@@ -361,42 +361,20 @@ gives rise to the instance declarations
          op Unit      = ...
 
 \begin{code}
-mkGenericDefMethBind :: Class -> [Type] -> Id -> TcM (LHsBind Name)
-mkGenericDefMethBind clas inst_tys sel_id
+mkGenericDefMethBind :: Class -> [Type] -> Id -> Name -> TcM (LHsBind Name)
+mkGenericDefMethBind clas inst_tys sel_id dm_name
   =    -- A generic default method
-       -- If the method is defined generically, we can only do the job if the
-       -- instance declaration is for a single-parameter type class with
-       -- a type constructor applied to type arguments in the instance decl
-       --      (checkTc, so False provokes the error)
-    do { checkTc (isJust maybe_tycon)
-                 (badGenericInstance sel_id (notSimple inst_tys))
-       ; checkTc (tyConHasGenerics tycon)
-                 (badGenericInstance sel_id (notGeneric tycon))
-
-       ; dflags <- getDOpts
+       -- If the method is defined generically, we only have to call the
+        -- dm_name.
+    do { dflags <- getDOpts
        ; liftIO (dumpIfSet_dyn dflags Opt_D_dump_deriv "Filling in method body"
                   (vcat [ppr clas <+> ppr inst_tys,
                          nest 2 (ppr sel_id <+> equals <+> ppr rhs)]))
 
-               -- Rename it before returning it
-       ; (rn_rhs, _) <- rnLExpr rhs
         ; return (noLoc $ mkFunBind (noLoc (idName sel_id))
-                                    [mkSimpleMatch [] rn_rhs]) }
+                                    [mkSimpleMatch [] rhs]) }
   where
-    rhs = mkGenericRhs sel_id clas_tyvar tycon
-
-         -- The tycon is only used in the generic case, and in that
-         -- case we require that the instance decl is for a single-parameter
-         -- type class with type variable arguments:
-         --    instance (...) => C (T a b)
-    clas_tyvar  = ASSERT (not (null (classTyVars clas))) head (classTyVars clas)
-    Just tycon = maybe_tycon
-    maybe_tycon = case inst_tys of 
-                       [ty] -> case tcSplitTyConApp_maybe ty of
-                                 Just (tycon, arg_tys) | all tcIsTyVarTy arg_tys -> Just tycon
-                                 _                                               -> Nothing
-                       _ -> Nothing
-
+    rhs = nlHsVar dm_name
 
 ---------------------------
 getGenericInstances :: [LTyClDecl Name] -> TcM [InstInfo Name]