import CmdLineOpts ( DynFlag(..), dopt )
-import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..),
+import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..),
MonoBinds(..), HsExpr(..), HsLit(..), Sig(..),
andMonoBindList, collectMonoBinders, isClassDecl
)
import TcBinds ( tcSpecSigs )
import TcClassDcl ( tcMethodBind, badMethodErr )
import TcMonad
+import TcType ( tcInstType )
import Inst ( InstOrigin(..),
- newDicts, newClassDicts,
- LIE, emptyLIE, plusLIE, plusLIEs )
+ newDicts, newClassDicts, instToId,
+ LIE, mkLIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
import TcEnv ( TcEnv, tcExtendGlobalValEnv,
tcExtendTyVarEnvForMeths,
- tcAddImportedIdInfo, tcInstId, tcLookupClass,
+ tcAddImportedIdInfo, tcLookupClass,
InstInfo(..), pprInstInfo, simpleInstInfoTyCon, simpleInstInfoTy,
newDFunName, tcExtendTyVarEnv
)
import InstEnv ( InstEnv, extendInstEnv )
-import TcMonoType ( tcTyVars, tcHsSigType, kcHsSigType )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( zonkTcSigTyVars )
+import TcMonoType ( tcTyVars, tcHsSigType, kcHsSigType, checkSigTyVars )
+import TcSimplify ( tcSimplifyCheck )
import HscTypes ( HomeSymbolTable, DFunId,
ModDetails(..), PackageInstEnv, PersistentRenamerState
)
-import Bag ( unionManyBags )
import DataCon ( classDataCon )
import Class ( Class, DefMeth(..), classBigSig )
import Var ( idName, idType )
+import VarSet ( emptyVarSet )
import Maybes ( maybeToBool )
import MkId ( mkDictFunId )
+import FunDeps ( checkInstFDs )
import Generics ( validGenericInstanceType )
import Module ( Module, foldModuleEnv )
import Name ( getSrcLoc )
import NameSet ( emptyNameSet, nameSetToList )
import PrelInfo ( eRROR_ID )
-import PprType ( pprConstraint, pprPred )
+import PprType ( pprClassPred, pprPred )
import TyCon ( TyCon, isSynTyCon )
import Type ( splitDFunTy, isTyVarTy,
splitTyConApp_maybe, splitDictTy,
getClassTys_maybe
)
import Subst ( mkTopTyVarSubst, substClasses )
-import VarSet ( mkVarSet, varSetElems )
+import VarSet ( varSetElems )
import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIImportResultTy )
import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey )
import Name ( Name )
\begin{code}
tcInstDecl1 :: TcEnv -> RenamedInstDecl -> NF_TcM [InstInfo]
-- Deal with a single instance declaration
-tcInstDecl1 unf_env (InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
+tcInstDecl1 unf_env decl@(InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
= -- Prime error recovery, set source location
recoverNF_Tc (returnNF_Tc []) $
tcAddSrcLoc src_loc $
-- Type-check all the stuff before the "where"
- tcHsSigType poly_ty `thenTc` \ poly_ty' ->
+ tcAddErrCtxt (instDeclCtxt poly_ty) (
+ tcHsSigType poly_ty
+ ) `thenTc` \ poly_ty' ->
let
(tyvars, theta, clas, inst_tys) = splitDFunTy poly_ty'
in
-- Imported ones should have been checked already, and may indeed
-- contain something illegal in normal Haskell, notably
-- instance CCallable [Char]
-
- getDOptsTc `thenTc` \ dflags ->
- scrutiniseInstanceHead dflags clas inst_tys `thenNF_Tc_`
- mapNF_Tc (scrutiniseInstanceConstraint dflags) theta `thenNF_Tc_`
+ getDOptsTc `thenTc` \ dflags ->
+ checkInstValidity dflags theta clas inst_tys `thenTc_`
-- Make the dfun id and return it
newDFunName clas inst_tys src_loc `thenNF_Tc` \ dfun_name ->
tcAddSrcLoc (getSrcLoc dfun_id) $
-- Instantiate the instance decl with tc-style type variables
- tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
+ tcInstType (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
let
(clas, inst_tys') = splitDictTy dict_ty'
origin = InstanceDeclOrigin
mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_`
-- Create dictionary Ids from the specified instance contexts.
- newClassDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
- newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
- newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ (this_dict, [this_dict_id]) ->
+ newClassDicts origin sc_theta' `thenNF_Tc` \ sc_dicts ->
+ newDicts origin dfun_theta' `thenNF_Tc` \ dfun_arg_dicts ->
+ newClassDicts origin [(clas,inst_tys')] `thenNF_Tc` \ [this_dict] ->
tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
tcExtendGlobalValEnv dm_ids (
dfun_theta'
monobinds uprags True)
op_items
- )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
+ )) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) ->
-- Deal with SPECIALISE instance pragmas by making them
-- look like SPECIALISE pragmas for the dfun
) `thenTc` \ (prag_binds, prag_lie) ->
-- Check the overloading constraints of the methods and superclasses
-
- -- tcMethodBind has checked that the class_tyvars havn't
- -- been unified with each other or another type, but we must
- -- still zonk them before passing them to tcSimplifyAndCheck
- zonkTcSigTyVars inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
let
- inst_tyvars_set = mkVarSet zonked_inst_tyvars
-
- (meth_lies, meth_ids) = unzip meth_lies_w_ids
-
-- These insts are in scope; quite a few, eh?
- avail_insts = this_dict `plusLIE`
- dfun_arg_dicts `plusLIE`
- sc_dicts `plusLIE`
- unionManyBags meth_lies
+ avail_insts = [this_dict] ++
+ dfun_arg_dicts ++
+ sc_dicts ++
+ meth_insts
- methods_lie = plusLIEs insts_needed_s
+ methods_lie = plusLIEs insts_needed_s
in
-- Simplify the constraints from methods
tcAddErrCtxt methodCtxt (
- tcSimplifyAndCheck
+ tcSimplifyCheck
(ptext SLIT("instance declaration context"))
- inst_tyvars_set -- Local tyvars
+ inst_tyvars'
avail_insts
methods_lie
) `thenTc` \ (const_lie1, lie_binds1) ->
-- Figure out bindings for the superclass context
tcAddErrCtxt superClassCtxt (
- tcSimplifyAndCheck
+ tcSimplifyCheck
(ptext SLIT("instance declaration context"))
- inst_tyvars_set
+ inst_tyvars'
dfun_arg_dicts -- NB! Don't include this_dict here, else the sc_dicts
-- get bound by just selecting from this_dict!!
- sc_dicts
- ) `thenTc` \ (const_lie2, lie_binds2) ->
-
+ (mkLIE sc_dicts)
+ ) `thenTc` \ (const_lie2, lie_binds2) ->
+
+ checkSigTyVars inst_tyvars' emptyVarSet `thenNF_Tc` \ zonked_inst_tyvars ->
-- Create the result bindings
let
dict_constr = classDataCon clas
- scs_and_meths = sc_dict_ids ++ meth_ids
+ scs_and_meths = map instToId (sc_dicts ++ meth_insts)
+ this_dict_id = instToId this_dict
dict_rhs
| null scs_and_meths
(HsLit (HsString msg))
| otherwise -- The common case
- = mkHsConApp dict_constr inst_tys' (map HsVar (sc_dict_ids ++ meth_ids))
+ = mkHsConApp dict_constr inst_tys' (map HsVar scs_and_meths)
-- 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
main_bind
= AbsBinds
zonked_inst_tyvars
- dfun_arg_dicts_ids
+ (map instToId dfun_arg_dicts)
[(inst_tyvars', dfun_id, this_dict_id)]
emptyNameSet -- No inlines (yet)
(lie_binds1 `AndMonoBinds`
We can also have instances for functions: @instance Foo (a -> b) ...@.
\begin{code}
-scrutiniseInstanceConstraint dflags pred
+checkInstValidity dflags theta clas inst_tys
+ | null errs = returnTc ()
+ | otherwise = addErrsTc errs `thenNF_Tc_` failTc
+ where
+ errs = checkInstHead dflags clas inst_tys ++
+ [err | pred <- theta, err <- checkInstConstraint dflags pred]
+
+checkInstConstraint dflags pred
| dopt Opt_AllowUndecidableInstances dflags
- = returnNF_Tc ()
+ = []
| Just (clas,tys) <- getClassTys_maybe pred,
all isTyVarTy tys
- = returnNF_Tc ()
+ = []
| otherwise
- = addErrTc (instConstraintErr pred)
+ = [instConstraintErr pred]
-scrutiniseInstanceHead dflags clas inst_taus
+checkInstHead dflags clas inst_taus
| -- CCALL CHECK
-- A user declaration of a CCallable/CReturnable instance
-- must be for a "boxed primitive" type.
||
(clas `hasKey` cReturnableClassKey
&& not (creturnable_type first_inst_tau))
- = addErrTc (nonBoxedPrimCCallErr clas first_inst_tau)
-
- -- Allow anything for AllowUndecidableInstances
- | dopt Opt_AllowUndecidableInstances dflags
- = returnNF_Tc ()
+ = [nonBoxedPrimCCallErr clas first_inst_tau]
-- If GlasgowExts then check at least one isn't a type variable
- | dopt Opt_GlasgowExts dflags
- = if all isTyVarTy inst_taus
- then addErrTc (instTypeErr clas inst_taus
- (text "There must be at least one non-type-variable in the instance head"))
- else returnNF_Tc ()
+ | dopt Opt_GlasgowExts dflags
+ = -- GlasgowExts case
+ check_tyvars dflags clas inst_taus ++ check_fundeps dflags clas inst_taus
-- WITH HASKELL 1.4, MUST HAVE C (T a b c)
- | not (length inst_taus == 1 &&
- maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor
- not (isSynTyCon tycon) && -- ...but not a synonym
- all isTyVarTy arg_tys && -- Applied to type variables
- length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
+ | not (length inst_taus == 1 &&
+ maybeToBool maybe_tycon_app && -- Yes, there's a type constuctor
+ not (isSynTyCon tycon) && -- ...but not a synonym
+ all isTyVarTy arg_tys && -- Applied to type variables
+ length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
-- This last condition checks that all the type variables are distinct
- )
- = addErrTc (instTypeErr clas inst_taus
- (text "the instance type must be of form (T a b c)" $$
- text "where T is not a synonym, and a,b,c are distinct type variables")
- )
+ )
+ = [instTypeErr clas inst_taus
+ (text "the instance type must be of form (T a b c)" $$
+ text "where T is not a synonym, and a,b,c are distinct type variables")]
| otherwise
- = returnNF_Tc ()
+ = []
where
(first_inst_tau : _) = inst_taus
ccallable_type dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty
creturnable_type ty = isFFIImportResultTy dflags ty
+
+check_tyvars dflags clas inst_taus
+ -- Check that at least one isn't a type variable
+ -- unless -fallow-undecideable-instances
+ | dopt Opt_AllowUndecidableInstances dflags = []
+ | not (all isTyVarTy inst_taus) = []
+ | otherwise = [the_err]
+ where
+ the_err = instTypeErr clas inst_taus msg
+ msg = ptext SLIT("There must be at least one non-type-variable in the instance head")
+
+check_fundeps dflags clas inst_taus
+ | checkInstFDs clas inst_taus = []
+ | otherwise = [the_err]
+ where
+ the_err = instTypeErr clas inst_taus msg
+ msg = ptext SLIT("the instance types do not agree with the functional dependencies of the class")
\end{code}
ctxt = hsep [ptext SLIT("In the"), text thing,
ptext SLIT("declaration for"), quotes (ppr (tcdName decl))]
+
+instDeclCtxt inst_ty = ptext SLIT("In the instance declaration for") <+> quotes doc
+ where
+ doc = case inst_ty of
+ HsForAllTy _ _ (HsPredTy pred) -> ppr pred
+ HsPredTy pred -> ppr pred
+ other -> ppr inst_ty -- Don't expect this
\end{code}
\begin{code}
ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst)
instTypeErr clas tys msg
- = sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
+ = sep [ptext SLIT("Illegal instance declaration for") <+>
+ quotes (pprClassPred clas tys),
nest 4 (parens msg)
]
nonBoxedPrimCCallErr clas inst_ty
= hang (ptext SLIT("Unacceptable instance type for ccall-ish class"))
- 4 (hsep [ ptext SLIT("class"), ppr clas, ptext SLIT("type"),
- ppr inst_ty])
+ 4 (pprClassPred clas [inst_ty])
methodCtxt = ptext SLIT("When checking the methods of an instance declaration")
superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
projects / ghc-hetmet.git / blobdiff