import {-# SOURCE #-} RnExpr( rnLExpr, rnStmts )
import HsSyn
-import RdrHsSyn
import RnHsSyn
import TcRnMonad
import RnTypes ( rnHsSigType, rnLHsType, checkPrecMatch)
rnBind _ trim (L loc bind@(PatBind { pat_lhs = pat
, pat_rhs = grhss
-- pat fvs were stored in bind_fvs
- -- after processing the LHS
+ -- after processing the LHS
, bind_fvs = pat_fvs }))
= setSrcSpan loc $
do { let bndrs = collectPatBinders pat
, fun_infix = is_infix
, fun_matches = matches }))
-- invariant: no free vars here when it's a FunBind
- = setSrcSpan loc $
+ = setSrcSpan loc $
do { let plain_name = unLoc name
; (matches', fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
\begin{code}
rnMethodBinds :: Name -- Class name
-> (Name -> [Name]) -- Signature tyvar function
- -> [Name] -- Names for generic type variables
-> LHsBinds RdrName
-> RnM (LHsBinds Name, FreeVars)
-rnMethodBinds cls sig_fn gen_tyvars binds
- = foldlM do_one (emptyBag,emptyFVs) (bagToList binds)
+rnMethodBinds cls sig_fn binds
+ = do { checkDupRdrNames meth_names
+ -- Check that the same method is not given twice in the
+ -- same instance decl instance C T where
+ -- f x = ...
+ -- g y = ...
+ -- f x = ...
+ -- We must use checkDupRdrNames because the Name of the
+ -- method is the Name of the class selector, whose SrcSpan
+ -- points to the class declaration; and we use rnMethodBinds
+ -- for instance decls too
+
+ ; foldlM do_one (emptyBag, emptyFVs) (bagToList binds) }
where
+ meth_names = collectMethodBinders binds
do_one (binds,fvs) bind
- = do { (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind
+ = do { (bind', fvs_bind) <- rnMethodBind cls sig_fn bind
; return (binds `unionBags` bind', fvs_bind `plusFV` fvs) }
rnMethodBind :: Name
-> (Name -> [Name])
- -> [Name]
-> LHsBindLR RdrName RdrName
-> RnM (Bag (LHsBindLR Name Name), FreeVars)
-rnMethodBind cls sig_fn gen_tyvars
+rnMethodBind cls sig_fn
(L loc bind@(FunBind { fun_id = name, fun_infix = is_infix
, fun_matches = MatchGroup matches _ }))
= setSrcSpan loc $ do
-- We use the selector name as the binder
(new_matches, fvs) <- bindSigTyVarsFV (sig_fn plain_name) $
- mapFvRn (rn_match (FunRhs plain_name is_infix)) matches
+ mapFvRn (rnMatch (FunRhs plain_name is_infix)) matches
let new_group = MatchGroup new_matches placeHolderType
when is_infix $ checkPrecMatch plain_name new_group
, bind_fvs = fvs })),
fvs `addOneFV` plain_name)
-- The 'fvs' field isn't used for method binds
- where
- -- Truly gruesome; bring into scope the correct members of the generic
- -- type variables. See comments in RnSource.rnSourceDecl(ClassDecl)
- rn_match info match@(L _ (Match (L _ (TypePat ty) : _) _ _))
- = extendTyVarEnvFVRn gen_tvs $
- rnMatch info match
- where
- tvs = map (rdrNameOcc.unLoc) (extractHsTyRdrTyVars ty)
- gen_tvs = [tv | tv <- gen_tyvars, nameOccName tv `elem` tvs]
-
- rn_match info match = rnMatch info match
-- Can't handle method pattern-bindings which bind multiple methods.
-rnMethodBind _ _ _ (L loc bind@(PatBind {})) = do
+rnMethodBind _ _ (L loc bind@(PatBind {})) = do
addErrAt loc (methodBindErr bind)
return (emptyBag, emptyFVs)
-rnMethodBind _ _ _ b = pprPanic "rnMethodBind" (ppr b)
+rnMethodBind _ _ b = pprPanic "rnMethodBind" (ppr b)
\end{code}
-- Check for duplicates on RdrName version,
-- because renamed version has unboundName for
-- not-in-scope binders, which gives bogus dup-sig errors
-
+ -- NB: in a class decl, a 'generic' sig is not considered
+ -- equal to an ordinary sig, so we allow, say
+ -- class C a where
+ -- op :: a -> a
+ -- default op :: Eq a => a -> a
+
; sigs' <- mapM (wrapLocM (renameSig mb_names)) sigs
; let (good_sigs, bad_sigs) = partition (ok_sig . unLoc) sigs'
; new_ty <- rnHsSigType (quotes (ppr v)) ty
; return (TypeSig new_v new_ty) }
+renameSig mb_names sig@(GenericSig v ty)
+ = do { defaultSigs_on <- xoptM Opt_DefaultSignatures
+ ; unless defaultSigs_on (addErr (defaultSigErr sig))
+ ; new_v <- lookupSigOccRn mb_names sig v
+ ; new_ty <- rnHsSigType (quotes (ppr v)) ty
+ ; return (GenericSig new_v new_ty) }
+
renameSig _ (SpecInstSig ty)
= do { new_ty <- rnLHsType (text "A SPECIALISE instance pragma") ty
; return (SpecInstSig new_ty) }
-- Standard Haskell 1.4 guards are just a single boolean
-- expression, rather than a list of qualifiers as in the
-- Glasgow extension
- is_standard_guard [] = True
- is_standard_guard [L _ (ExprStmt _ _ _)] = True
- is_standard_guard _ = False
+ is_standard_guard [] = True
+ is_standard_guard [L _ (ExprStmt _ _ _ _)] = True
+ is_standard_guard _ = False
\end{code}
%************************************************************************
= addErrAt loc $
sep [ptext (sLit "Misplaced") <+> hsSigDoc sig <> colon, ppr sig]
+defaultSigErr :: Sig RdrName -> SDoc
+defaultSigErr sig = vcat [ hang (ptext (sLit "Unexpected default signature:"))
+ 2 (ppr sig)
+ , ptext (sLit "Use -XDefaultSignatures to enable default signatures") ]
+
methodBindErr :: HsBindLR RdrName RdrName -> SDoc
methodBindErr mbind
= hang (ptext (sLit "Pattern bindings (except simple variables) not allowed in instance declarations"))
nonStdGuardErr guards
= hang (ptext (sLit "accepting non-standard pattern guards (use -XPatternGuards to suppress this message)"))
4 (interpp'SP guards)
+
\end{code}
projects / ghc-hetmet.git / blobdiff