import FamInstEnv
import TcDeriv
import TcEnv
-import RnEnv ( lookupImportedName )
+import RnEnv ( lookupGlobalOccRn )
+import RnSource ( addTcgDUs )
import TcHsType
import TcUnify
import TcSimplify
import Type
import Coercion
import TyCon
-import TypeRep
import DataCon
import Class
import Var
inline df_i in it, and that in turn means that (since it'll be a
loop-breaker because df_i isn't), op1_i will ironically never be
inlined. We need to fix this somehow -- perhaps allowing inlining
- of INLINE funcitons inside other INLINE functions.
+ of INLINE functions inside other INLINE functions.
Note [Subtle interaction of recursion and overlap]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
; let { (local_info,
at_tycons_s) = unzip local_info_tycons
- ; at_idx_tycon = concat at_tycons_s ++ idx_tycons
+ ; at_idx_tycons = concat at_tycons_s ++ idx_tycons
; clas_decls = filter (isClassDecl.unLoc) tycl_decls
- ; implicit_things = concatMap implicitTyThings at_idx_tycon
+ ; implicit_things = concatMap implicitTyThings at_idx_tycons
+ ; aux_binds = mkAuxBinds at_idx_tycons
}
-- (2) Add the tycons of indexed types and their implicit
-- tythings to the global environment
- ; tcExtendGlobalEnv (at_idx_tycon ++ implicit_things) $ do {
+ ; tcExtendGlobalEnv (at_idx_tycons ++ implicit_things) $ do {
-- (3) Instances from generic class declarations
; generic_inst_info <- getGenericInstances clas_decls
-- a) local instance decls
-- b) generic instances
-- c) local family instance decls
- ; addInsts local_info $ do {
- ; addInsts generic_inst_info $ do {
- ; addFamInsts at_idx_tycon $ do {
+ ; addInsts local_info $
+ addInsts generic_inst_info $
+ addFamInsts at_idx_tycons $ do {
-- (4) Compute instances from "deriving" clauses;
-- This stuff computes a context for the derived instance
failIfErrsM -- If the addInsts stuff gave any errors, don't
-- try the deriving stuff, becuase that may give
-- more errors still
- ; (deriv_inst_info, deriv_binds) <- tcDeriving tycl_decls inst_decls
- deriv_decls
- ; addInsts deriv_inst_info $ do {
-
- ; gbl_env <- getGblEnv
- ; return (gbl_env,
+ ; (deriv_inst_info, deriv_binds, deriv_dus)
+ <- tcDeriving tycl_decls inst_decls deriv_decls
+ ; gbl_env <- addInsts deriv_inst_info getGblEnv
+ ; return ( addTcgDUs gbl_env deriv_dus,
generic_inst_info ++ deriv_inst_info ++ local_info,
- deriv_binds)
- }}}}}}
+ aux_binds `plusHsValBinds` deriv_binds)
+ }}}
where
-- Make sure that toplevel type instance are not for associated types.
-- !!!TODO: Need to perform this check for the TyThing of type functions,
ispec = mkLocalInstance dfun overlap_flag
; return (InstInfo { iSpec = ispec,
- iBinds = VanillaInst binds uprags },
+ iBinds = VanillaInst binds uprags False },
idx_tycons)
}
where
; mapM_ (checkIndexes clas inst_tys) ats
}
- checkIndexes clas inst_tys (hsAT, ATyCon tycon) =
+ checkIndexes clas inst_tys (hsAT, ATyCon tycon)
-- !!!TODO: check that this does the Right Thing for indexed synonyms, too!
- checkIndexes' clas inst_tys hsAT
- (tyConTyVars tycon,
- snd . fromJust . tyConFamInst_maybe $ tycon)
+ = checkIndexes' clas inst_tys hsAT
+ (tyConTyVars tycon,
+ snd . fromJust . tyConFamInst_maybe $ tycon)
checkIndexes _ _ _ = panic "checkIndexes"
checkIndexes' clas (instTvs, instTys) hsAT (atTvs, atTys)
addErrCtxt (atInstCtxt atName) $
case find ((atName ==) . tyConName) (classATs clas) of
Nothing -> addErrTc $ badATErr clas atName -- not in this class
- Just atDecl ->
- case assocTyConArgPoss_maybe atDecl of
+ Just atycon ->
+ case assocTyConArgPoss_maybe atycon of
Nothing -> panic "checkIndexes': AT has no args poss?!?"
Just poss ->
-- which must be type variables; and (3) variables in AT and
-- instance head will be different `Name's even if their
-- source lexemes are identical.
+ --
+ -- e.g. class C a b c where
+ -- data D b a :: * -> * -- NB (1) b a, omits c
+ -- instance C [x] Bool Char where
+ -- data D Bool [x] v = MkD x [v] -- NB (2) v
+ -- -- NB (3) the x in 'instance C...' have differnt
+ -- -- Names to x's in 'data D...'
--
-- Re (1), `poss' contains a permutation vector to extract the
-- class parameters in the right order.
unionManyBags inst_binds_s
; tcl_env <- getLclEnv -- Default method Ids in here
; return (binds, tcl_env) }
+
+tcInstDecl2 :: InstInfo Name -> TcM (LHsBinds Id)
+tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = ibinds })
+ = recoverM (return emptyLHsBinds) $
+ setSrcSpan loc $
+ addErrCtxt (instDeclCtxt2 (idType dfun_id)) $
+ tc_inst_decl2 dfun_id ibinds
+ where
+ dfun_id = instanceDFunId ispec
+ loc = getSrcSpan dfun_id
\end{code}
\begin{code}
-tcInstDecl2 :: InstInfo Name -> TcM (LHsBinds Id)
+tc_inst_decl2 :: Id -> InstBindings Name -> TcM (LHsBinds Id)
-- Returns a binding for the dfun
------------------------
-- If there are no superclasses, matters are simpler, because we don't need the case
-- see Note [Newtype deriving superclasses] in TcDeriv.lhs
-tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = NewTypeDerived })
- = do { let dfun_id = instanceDFunId ispec
- rigid_info = InstSkol
+tc_inst_decl2 dfun_id (NewTypeDerived coi)
+ = do { let rigid_info = InstSkol
origin = SigOrigin rigid_info
inst_ty = idType dfun_id
; (inst_tvs', theta, inst_head_ty) <- tcSkolSigType rigid_info inst_ty
(class_tyvars, sc_theta, _, _) = classBigSig cls
cls_tycon = classTyCon cls
sc_theta' = substTheta (zipOpenTvSubst class_tyvars cls_inst_tys) sc_theta
-
Just (initial_cls_inst_tys, last_ty) = snocView cls_inst_tys
- (nt_tycon, tc_args) = tcSplitTyConApp last_ty -- Can't fail
- rep_ty = newTyConInstRhs nt_tycon tc_args
- rep_pred = mkClassPred cls (initial_cls_inst_tys ++ [rep_ty])
- -- In our example, rep_pred is (Foo Int (Tree [a]))
- the_coercion = make_coercion cls_tycon initial_cls_inst_tys nt_tycon tc_args
- -- Coercion of kind (Foo Int (Tree [a]) ~ Foo Int (N a)
+ (rep_ty, wrapper)
+ = case coi of
+ IdCo -> (last_ty, idHsWrapper)
+ ACo co -> (snd (coercionKind co), WpCast (mk_full_coercion co))
+
+ -----------------------
+ -- mk_full_coercion
+ -- The inst_head looks like (C s1 .. sm (T a1 .. ak))
+ -- But we want the coercion (C s1 .. sm (sym (CoT a1 .. ak)))
+ -- with kind (C s1 .. sm (T a1 .. ak) ~ C s1 .. sm <rep_ty>)
+ -- where rep_ty is the (eta-reduced) type rep of T
+ -- So we just replace T with CoT, and insert a 'sym'
+ -- NB: we know that k will be >= arity of CoT, because the latter fully eta-reduced
+
+ mk_full_coercion co = mkTyConApp cls_tycon
+ (initial_cls_inst_tys ++ [mkSymCoercion co])
+ -- Full coercion : (Foo Int (Tree [a]) ~ Foo Int (N a)
+
+ rep_pred = mkClassPred cls (initial_cls_inst_tys ++ [rep_ty])
+ -- In our example, rep_pred is (Foo Int (Tree [a]))
; sc_loc <- getInstLoc InstScOrigin
; sc_dicts <- newDictBndrs sc_loc sc_theta'
; inst_loc <- getInstLoc origin
; dfun_dicts <- newDictBndrs inst_loc theta
- ; this_dict <- newDictBndr inst_loc (mkClassPred cls cls_inst_tys)
; rep_dict <- newDictBndr inst_loc rep_pred
+ ; this_dict <- newDictBndr inst_loc (mkClassPred cls cls_inst_tys)
-- Figure out bindings for the superclass context from dfun_dicts
-- Don't include this_dict in the 'givens', else
-- in the envt with one of the clas_tyvars
; checkSigTyVars inst_tvs'
- ; let coerced_rep_dict = wrapId the_coercion (instToId rep_dict)
+ ; let coerced_rep_dict = wrapId wrapper (instToId rep_dict)
; body <- make_body cls_tycon cls_inst_tys sc_dicts coerced_rep_dict
- ; let dict_bind = mkVarBind (instToId this_dict) (noLoc body)
+ ; let dict_bind = noLoc $ VarBind (instToId this_dict) (noLoc body)
; return (unitBag $ noLoc $
AbsBinds inst_tvs' (map instToVar dfun_dicts)
(dict_bind `consBag` sc_binds)) }
where
-----------------------
- -- make_coercion
- -- The inst_head looks like (C s1 .. sm (T a1 .. ak))
- -- But we want the coercion (C s1 .. sm (sym (CoT a1 .. ak)))
- -- with kind (C s1 .. sm (T a1 .. ak) ~ C s1 .. sm <rep_ty>)
- -- where rep_ty is the (eta-reduced) type rep of T
- -- So we just replace T with CoT, and insert a 'sym'
- -- NB: we know that k will be >= arity of CoT, because the latter fully eta-reduced
-
- make_coercion cls_tycon initial_cls_inst_tys nt_tycon tc_args
- | Just co_con <- newTyConCo_maybe nt_tycon
- , let co = mkSymCoercion (mkTyConApp co_con tc_args)
- = WpCast (mkTyConApp cls_tycon (initial_cls_inst_tys ++ [co]))
- | otherwise -- The newtype is transparent; no need for a cast
- = idHsWrapper
-
- -----------------------
-- (make_body C tys scs coreced_rep_dict)
-- returns
-- (case coerced_rep_dict of { C _ ops -> C scs ops })
------------------------
-- Ordinary instances
-tcInstDecl2 (InstInfo { iSpec = ispec, iBinds = VanillaInst monobinds uprags })
- = let
- dfun_id = instanceDFunId ispec
- rigid_info = InstSkol
- inst_ty = idType dfun_id
- loc = getSrcSpan dfun_id
- in
- -- Prime error recovery
- recoverM (return emptyLHsBinds) $
- setSrcSpan loc $
- addErrCtxt (instDeclCtxt2 (idType dfun_id)) $ do
+tc_inst_decl2 dfun_id (VanillaInst monobinds uprags standalone_deriv)
+ = do { let rigid_info = InstSkol
+ inst_ty = idType dfun_id
-- Instantiate the instance decl with skolem constants
- (inst_tyvars', dfun_theta', inst_head') <- tcSkolSigType rigid_info inst_ty
+ ; (inst_tyvars', dfun_theta', inst_head') <- tcSkolSigType rigid_info inst_ty
-- These inst_tyvars' scope over the 'where' part
-- Those tyvars are inside the dfun_id's type, which is a bit
-- bizarre, but OK so long as you realise it!
- let
- (clas, inst_tys') = tcSplitDFunHead inst_head'
- (class_tyvars, sc_theta, _, op_items) = classBigSig clas
+ ; let
+ (clas, inst_tys') = tcSplitDFunHead inst_head'
+ (class_tyvars, sc_theta, _, op_items) = classBigSig clas
- -- Instantiate the super-class context with inst_tys
- sc_theta' = substTheta (zipOpenTvSubst class_tyvars inst_tys') sc_theta
- origin = SigOrigin rigid_info
+ -- Instantiate the super-class context with inst_tys
+ sc_theta' = substTheta (zipOpenTvSubst class_tyvars inst_tys') sc_theta
+ origin = SigOrigin rigid_info
-- Create dictionary Ids from the specified instance contexts.
- sc_loc <- getInstLoc InstScOrigin
- sc_dicts <- newDictOccs sc_loc sc_theta' -- These are wanted
- inst_loc <- getInstLoc origin
- dfun_dicts <- newDictBndrs inst_loc dfun_theta' -- Includes equalities
- this_dict <- newDictBndr inst_loc (mkClassPred clas inst_tys')
+ ; sc_loc <- getInstLoc InstScOrigin
+ ; sc_dicts <- newDictOccs sc_loc sc_theta' -- These are wanted
+ ; inst_loc <- getInstLoc origin
+ ; dfun_dicts <- newDictBndrs inst_loc dfun_theta' -- Includes equalities
+ ; this_dict <- newDictBndr inst_loc (mkClassPred clas inst_tys')
+
-- Default-method Ids may be mentioned in synthesised RHSs,
-- but they'll already be in the environment.
-- Typecheck the methods
- let this_dict_id = instToId this_dict
- dfun_lam_vars = map instToVar dfun_dicts -- Includes equalities
- prag_fn = mkPragFun uprags
- tc_meth = tcInstanceMethod loc clas inst_tyvars'
- dfun_dicts
- dfun_theta' inst_tys'
- this_dict dfun_id
- prag_fn monobinds
- (meth_exprs, meth_binds) <- tcExtendTyVarEnv inst_tyvars' $
+ ; let this_dict_id = instToId this_dict
+ dfun_lam_vars = map instToVar dfun_dicts -- Includes equalities
+ prag_fn = mkPragFun uprags
+ loc = getSrcSpan dfun_id
+ tc_meth = tcInstanceMethod loc standalone_deriv
+ clas inst_tyvars' dfun_dicts
+ dfun_theta' inst_tys'
+ this_dict dfun_id
+ prag_fn monobinds
+ ; (meth_exprs, meth_binds) <- tcExtendTyVarEnv inst_tyvars' $
mapAndUnzipM tc_meth op_items
- -- Figure out bindings for the superclass context
- -- Don't include this_dict in the 'givens', else
- -- sc_dicts get bound by just selecting from this_dict!!
- sc_binds <- addErrCtxt superClassCtxt $
- tcSimplifySuperClasses inst_loc this_dict dfun_dicts sc_dicts
+ -- Figure out bindings for the superclass context
+ -- Don't include this_dict in the 'givens', else
+ -- sc_dicts get bound by just selecting from this_dict!!
+ ; sc_binds <- addErrCtxt superClassCtxt $
+ tcSimplifySuperClasses inst_loc this_dict dfun_dicts sc_dicts
-- Note [Recursive superclasses]
-- It's possible that the superclass stuff might unified something
-- in the envt with one of the inst_tyvars'
- checkSigTyVars inst_tyvars'
-
- -- Deal with 'SPECIALISE instance' pragmas
- prags <- tcPrags NonRecursive dfun_id (filter isSpecInstLSig uprags)
-
- -- Create the result bindings
- let
- dict_constr = classDataCon clas
- inline_prag | null dfun_dicts = []
- | otherwise = [L loc (InlinePrag (Inline AlwaysActive True))]
- -- Always inline the dfun; this is an experimental decision
- -- because it makes a big performance difference sometimes.
- -- Often it means we can do the method selection, and then
- -- inline the method as well. Marcin's idea; see comments below.
- --
- -- BUT: don't inline it if it's a constant dictionary;
- -- we'll get all the benefit without inlining, and we get
- -- a **lot** of code duplication if we inline it
- --
- -- See Note [Inline dfuns] below
-
- sc_dict_vars = map instToVar sc_dicts
- dict_bind = mkVarBind this_dict_id dict_rhs
- dict_rhs = foldl (\ f a -> L loc (HsApp f (L loc a))) inst_constr meth_exprs
- inst_constr = L loc $ wrapId (mkWpApps sc_dict_vars <.> mkWpTyApps inst_tys')
- (dataConWrapId dict_constr)
- -- We don't produce a binding for the dict_constr; instead we
- -- rely on the simplifier to unfold this saturated application
- -- We do this rather than generate an HsCon directly, because
- -- it means that the special cases (e.g. dictionary with only one
- -- member) are dealt with by the common MkId.mkDataConWrapId code rather
- -- than needing to be repeated here.
-
- main_bind = noLoc $ AbsBinds
- inst_tyvars'
- dfun_lam_vars
- [(inst_tyvars', dfun_id, this_dict_id, inline_prag ++ prags)]
- (dict_bind `consBag` sc_binds)
-
- showLIE (text "instance")
- return (main_bind `consBag` unionManyBags meth_binds)
+ ; checkSigTyVars inst_tyvars'
+
+ -- Deal with 'SPECIALISE instance' pragmas
+ ; prags <- tcPrags dfun_id (filter isSpecInstLSig uprags)
+
+ -- Create the result bindings
+ ; let dict_constr = classDataCon clas
+ inline_prag | null dfun_dicts = []
+ | otherwise = [L loc (InlinePrag (alwaysInlineSpec FunLike))]
+ -- Always inline the dfun; this is an experimental decision
+ -- because it makes a big performance difference sometimes.
+ -- Often it means we can do the method selection, and then
+ -- inline the method as well. Marcin's idea; see comments below.
+ --
+ -- BUT: don't inline it if it's a constant dictionary;
+ -- we'll get all the benefit without inlining, and we get
+ -- a **lot** of code duplication if we inline it
+ --
+ -- See Note [Inline dfuns] below
+
+ sc_dict_vars = map instToVar sc_dicts
+ dict_bind = L loc (VarBind this_dict_id dict_rhs)
+ dict_rhs = foldl (\ f a -> L loc (HsApp f (L loc a))) inst_constr meth_exprs
+ inst_constr = L loc $ wrapId (mkWpApps sc_dict_vars <.> mkWpTyApps inst_tys')
+ (dataConWrapId dict_constr)
+ -- We don't produce a binding for the dict_constr; instead we
+ -- rely on the simplifier to unfold this saturated application
+ -- We do this rather than generate an HsCon directly, because
+ -- it means that the special cases (e.g. dictionary with only one
+ -- member) are dealt with by the common MkId.mkDataConWrapId code rather
+ -- than needing to be repeated here.
+
+
+ main_bind = noLoc $ AbsBinds
+ inst_tyvars'
+ dfun_lam_vars
+ [(inst_tyvars', dfun_id, this_dict_id, inline_prag ++ prags)]
+ (dict_bind `consBag` sc_binds)
+
+ ; showLIE (text "instance")
+ ; return (main_bind `consBag` unionManyBags meth_binds) }
\end{code}
Note [Recursive superclasses]
- Use tcValBinds to do the checking
\begin{code}
-tcInstanceMethod :: SrcSpan -> Class -> [TcTyVar] -> [Inst]
+tcInstanceMethod :: SrcSpan -> Bool -> Class -> [TcTyVar] -> [Inst]
-> TcThetaType -> [TcType]
-> Inst -> Id
-> TcPragFun -> LHsBinds Name
-- The returned inst_meth_ids all have types starting
-- forall tvs. theta => ...
-tcInstanceMethod loc clas tyvars dfun_dicts theta inst_tys
+tcInstanceMethod loc standalone_deriv clas tyvars dfun_dicts theta inst_tys
this_dict dfun_id prag_fn binds_in (sel_id, dm_info)
= do { cloned_this <- cloneDict this_dict
-- Need to clone the dict in case it is floated out, and
-- then clashes with its friends
; uniq1 <- newUnique
; let local_meth_name = mkInternalName uniq1 sel_occ loc -- Same OccName
- this_dict_bind = mkVarBind (instToId cloned_this) $
+ this_dict_bind = L loc $ VarBind (instToId cloned_this) $
L loc $ wrapId meth_wrapper dfun_id
mb_this_bind | null tyvars = Nothing
| otherwise = Just (cloned_this, this_dict_bind)
-- involved; otherwise overlap is not possible
-- See Note [Subtle interaction of recursion and overlap]
- tc_body rn_bind = do { (meth_id, tc_binds) <- tcInstanceMethodBody
+ tc_body rn_bind
+ = add_meth_ctxt rn_bind $
+ do { (meth_id, tc_binds) <- tcInstanceMethodBody
InstSkol clas tyvars dfun_dicts theta inst_tys
mb_this_bind sel_id
local_meth_name
meth_sig_fn meth_prag_fn rn_bind
- ; return (wrapId meth_wrapper meth_id, tc_binds) }
+ ; return (wrapId meth_wrapper meth_id, tc_binds) }
; case (findMethodBind sel_name local_meth_name binds_in, dm_info) of
-- There is a user-supplied method binding, so use it
(Nothing, NoDefMeth) -> do -- No default method in the class
{ warn <- doptM Opt_WarnMissingMethods
; warnTc (warn -- Warn only if -fwarn-missing-methods
- && reportIfUnused (getOccName sel_id))
+ && not (startsWithUnderscore (getOccName sel_id)))
-- Don't warn about _foo methods
omitted_meth_warn
; return (error_rhs, emptyBag) }
{ -- Build the typechecked version directly,
-- without calling typecheck_method;
-- see Note [Default methods in instances]
- dm_name <- lookupImportedName (mkDefMethRdrName sel_name)
+ dm_name <- lookupGlobalOccRn (mkDefMethRdrName sel_name)
-- Might not be imported, but will be an OrigName
; dm_id <- tcLookupId dm_name
; return (wrapId dm_wrapper dm_id, emptyBag) } }
dfun_lam_vars = map instToVar dfun_dicts
meth_wrapper = mkWpApps dfun_lam_vars <.> mkWpTyApps (mkTyVarTys tyvars)
+ -- For instance decls that come from standalone deriving clauses
+ -- we want to print out the full source code if there's an error
+ -- because otherwise the user won't see the code at all
+ add_meth_ctxt rn_bind thing
+ | standalone_deriv = addLandmarkErrCtxt (derivBindCtxt clas inst_tys rn_bind) thing
+ | otherwise = thing
wrapId :: HsWrapper -> id -> HsExpr id
wrapId wrapper id = mkHsWrap wrapper (HsVar id)
+
+derivBindCtxt :: Class -> [Type ] -> LHsBind Name -> SDoc
+derivBindCtxt clas tys bind
+ = vcat [ ptext (sLit "When typechecking a standalone-derived method for")
+ <+> quotes (pprClassPred clas tys) <> colon
+ , nest 2 $ pprSetDepth AllTheWay $ ppr bind ]
\end{code}
Note [Default methods in instances]
wrongATArgErr :: Type -> Type -> SDoc
wrongATArgErr ty instTy =
sep [ ptext (sLit "Type indexes must match class instance head")
- , ptext (sLit "Found") <+> ppr ty <+> ptext (sLit "but expected") <+>
- ppr instTy
+ , ptext (sLit "Found") <+> quotes (ppr ty)
+ <+> ptext (sLit "but expected") <+> quotes (ppr instTy)
]
\end{code}
projects / ghc-hetmet.git / blobdiff