import Inst
import InstEnv
import TcEnv
+import TcPat( addInlinePrags )
import TcBinds
import TcUnify
import TcHsType
-- (If necessary we can fix that, but we don't have a convenient Id to hand.)
tcDefMeth clas tyvars this_dict binds_in sigs sig_fn prag_fn (sel_id, dm_info)
= case dm_info of
- NoDefMeth -> return emptyBag
+ NoDefMeth -> do { mapM_ (addLocM (badDmPrag sel_id)) prags
+ ; return emptyBag }
DefMeth dm_name -> tc_dm dm_name (instantiateMethod clas sel_id (mkTyVarTys tyvars))
GenDefMeth dm_name -> do { tau <- tc_genop_ty (findGenericSig sigs sel_name)
; tc_dm dm_name tau }
-- In the case of a generic default, we have to get the type from the signature
-- Otherwise we can get it by instantiating the method selector
where
- sel_name = idName sel_id
+ sel_name = idName sel_id
+ prags = prag_fn sel_name
+ dm_sig_fn _ = sig_fn sel_name
+ dm_bind = findMethodBind sel_name binds_in
+ `orElse` pprPanic "tcDefMeth" (ppr sel_id)
-- Eg. class C a where
-- op :: forall b. Eq b => a -> [b] -> a
-- Base the local_dm_name on the selector name, because
-- type errors from tcInstanceMethodBody come from here
- ; let meth_bind = findMethodBind sel_name binds_in
- `orElse` pprPanic "tcDefMeth" (ppr sel_id)
-
- dm_sig_fn _ = sig_fn sel_name
- dm_prag_fn _ = prag_fn sel_name
-
- dm_ty = mkSigmaTy tyvars [mkClassPred clas tyvars] local_dm_ty
+ ; let dm_ty = mkSigmaTy tyvars [mkClassPred clas (mkTyVarTys tyvars)] local_dm_ty
dm_id = mkExportedLocalId dm_name dm_ty
- local_dm_id = mkLocalId local_dm_name local_dm_type
+ local_dm_id = mkLocalId local_dm_name local_dm_ty
; dm_id_w_inline <- addInlinePrags dm_id prags
; spec_prags <- tcSpecPrags dm_id prags
(ptext (sLit "Ignoring SPECIALISE pragmas on default method")
<+> quotes (ppr sel_name))
- ; dm_bind <- tcInstanceMethodBody (ClsSkol clas) tyvars [this_dict]
+ ; tc_bind <- tcInstanceMethodBody (ClsSkol clas) tyvars [this_dict]
dm_id_w_inline local_dm_id dm_sig_fn
- IsDefaultMethodId dm_bind
+ IsDefaultMethod dm_bind
- ; return (unitBag dm_bind) }
+ ; return (unitBag tc_bind) }
tc_genop_ty :: LHsType Name -> TcM Type
tc_genop_ty hs_ty
; checkValidType (FunSigCtxt sel_name) tau
; return tau }
-findGenericSig :: [LSig Name] -> Name -> LSig Name
+findGenericSig :: [LSig Name] -> Name -> LHsType Name
-- Find the 'generic op :: ty' signature among the sigs
-- If dm_info is GenDefMeth, the corresponding signature
-- should jolly well exist! Hence the panic
]
where
ppr_inst_ty (_,inst) = ppr (simpleInstInfoTy inst)
+
+badDmPrag :: Id -> Sig Name -> TcM ()
+badDmPrag sel_id prag
+ = addErrTc (ptext (sLit "The") <+> hsSigDoc prag <+> ptext (sLit "for default method")
+ <+> quotes (ppr sel_id)
+ <+> ptext (sLit "lacks an accompanying binding"))
\end{code}