%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcInstDecls]{Typechecking instance declarations}
#include "HsVersions.h"
import HsSyn ( HsDecl(..), InstDecl(..),
- HsBinds(..), MonoBinds(..), GRHSsAndBinds(..), GRHS(..),
+ HsBinds(..), MonoBinds(..),
HsExpr(..), InPat(..), HsLit(..), Sig(..),
- unguardedRHS,
- collectMonoBinders, andMonoBinds
+ collectMonoBinders, andMonoBindList
)
-import HsBinds ( sigsForMe )
-import RnHsSyn ( RenamedHsBinds, RenamedMonoBinds,
- RenamedInstDecl, RenamedHsExpr,
- RenamedSig, RenamedHsDecl
- )
-import TcHsSyn ( TcMonoBinds, TcIdOcc(..), TcIdBndr,
- maybeBoxedPrimType, tcIdType
+import RnHsSyn ( RenamedHsBinds, RenamedInstDecl, RenamedHsDecl )
+import TcHsSyn ( TcMonoBinds,
+ maybeBoxedPrimType
)
import TcBinds ( tcPragmaSigs )
import Inst ( Inst, InstOrigin(..),
newDicts, LIE, emptyLIE, plusLIE, plusLIEs )
import TcDeriv ( tcDeriving )
-import TcEnv ( GlobalValueEnv, tcExtendGlobalValEnv, tcAddImportedIdInfo )
-import TcInstUtil ( InstInfo(..), mkInstanceRelatedIds, classDataCon )
-import TcKind ( TcKind, unifyKind )
-import TcMonoType ( tcHsType )
-import TcSimplify ( tcSimplifyAndCheck )
-import TcType ( TcType, TcTyVar, TcTyVarSet,
- zonkSigTyVar, tcInstSigTyVars, tcInstType, tcInstTheta
+import TcEnv ( ValueEnv, tcExtendGlobalValEnv, tcExtendTyVarEnvForMeths,
+ tcAddImportedIdInfo, tcInstId
)
+import TcInstUtil ( InstInfo(..), classDataCon )
+import TcMonoType ( tcHsTopType )
+import TcSimplify ( tcSimplifyAndCheck )
+import TcType ( TcTyVar, zonkTcTyVarBndr )
import Bag ( emptyBag, unitBag, unionBags, unionManyBags,
foldBag, bagToList, Bag
)
-import CmdLineOpts ( opt_GlasgowExts )
+import CmdLineOpts ( opt_GlasgowExts, opt_AllowUndecidableInstances )
import Class ( classBigSig, Class )
-import Id ( isNullaryDataCon, dataConArgTys, replaceIdInfo, idName, Id )
-import Maybes ( maybeToBool, seqMaybe, catMaybes )
-import Name ( nameOccName, mkLocalName,
- isLocallyDefined, Module,
+import Var ( setIdInfo, idName, idType, Id, TyVar )
+import DataCon ( isNullaryDataCon, dataConArgTys, dataConId )
+import Maybes ( maybeToBool, catMaybes, expectJust )
+import MkId ( mkDictFunId )
+import Name ( nameOccName, isLocallyDefined, Module,
NamedThing(..)
)
import PrelVals ( eRROR_ID )
-import PprType ( pprParendType, pprConstraint )
-import SrcLoc ( SrcLoc, noSrcLoc )
+import PprType ( pprConstraint )
+import SrcLoc ( SrcLoc )
import TyCon ( isSynTyCon, isDataTyCon, tyConDerivings )
-import Type ( Type, ThetaType, isUnpointedType,
- splitSigmaTy, isTyVarTy, mkSigmaTy,
+import Type ( Type, isUnLiftedType, mkTyVarTys,
+ splitSigmaTy, isTyVarTy,
splitTyConApp_maybe, splitDictTy_maybe,
- splitAlgTyConApp_maybe, splitRhoTy,
- tyVarsOfTypes
+ splitAlgTyConApp_maybe,
+ tyVarsOfTypes, substTopTheta
)
-import TyVar ( zipTyVarEnv, mkTyVarSet, tyVarSetToList, TyVar )
+import VarEnv ( zipVarEnv )
+import VarSet ( mkVarSet, varSetElems )
import TysPrim ( byteArrayPrimTyCon, mutableByteArrayPrimTyCon )
import TysWiredIn ( stringTy )
import Unique ( Unique, cCallableClassKey, cReturnableClassKey, Uniquable(..) )
\end{enumerate}
\begin{code}
-tcInstDecls1 :: GlobalValueEnv -- Contains IdInfo for dfun ids
+tcInstDecls1 :: ValueEnv -- Contains IdInfo for dfun ids
-> [RenamedHsDecl]
-> Module -- module name for deriving
-> RnNameSupply -- for renaming derivings
-> TcM s (Bag InstInfo,
- RenamedHsBinds,
- SDoc)
+ RenamedHsBinds)
tcInstDecls1 unf_env decls mod_name rn_name_supply
= -- Do the ordinary instance declarations
-- for things in this module; we ignore deriving decls from
-- interfaces!
tcDeriving mod_name rn_name_supply decl_inst_info
- `thenTc` \ (deriv_inst_info, deriv_binds, ddump_deriv) ->
+ `thenTc` \ (deriv_inst_info, deriv_binds) ->
let
full_inst_info = deriv_inst_info `unionBags` decl_inst_info
in
- returnTc (full_inst_info, deriv_binds, ddump_deriv)
+ returnTc (full_inst_info, deriv_binds)
-tcInstDecl1 :: GlobalValueEnv -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
+tcInstDecl1 :: ValueEnv -> Module -> RenamedInstDecl -> NF_TcM s (Bag InstInfo)
tcInstDecl1 unf_env mod_name (InstDecl poly_ty binds uprags (Just dfun_name) src_loc)
= -- Prime error recovery, set source location
tcAddSrcLoc src_loc $
-- Type-check all the stuff before the "where"
- tcHsType poly_ty `thenTc` \ poly_ty' ->
+ tcHsTopType poly_ty `thenTc` \ poly_ty' ->
let
(tyvars, theta, dict_ty) = splitSigmaTy poly_ty'
(clas, inst_tys) = case splitDictTy_maybe dict_ty of
Just pair -> pair
in
- -- Check for respectable instance type
- scrutiniseInstanceType clas inst_tys `thenTc_`
+ -- Check for respectable instance type, and context
+ -- but only do this for non-imported instance decls.
+ -- Imported ones should have been checked already, and may indeed
+ -- contain something illegal in normal Haskell, notably
+ -- instance CCallable [Char]
+ (if isLocallyDefined dfun_name then
+ scrutiniseInstanceHead clas inst_tys `thenNF_Tc_`
+ mapNF_Tc scrutiniseInstanceConstraint theta
+ else
+ returnNF_Tc []
+ ) `thenNF_Tc_`
-- Make the dfun id and constant-method ids
let
- (dfun_id, dfun_theta) = mkInstanceRelatedIds dfun_name
- clas tyvars inst_tys theta
+ dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta
+
-- Add info from interface file
final_dfun_id = tcAddImportedIdInfo unf_env dfun_id
in
returnTc (unitBag (InstInfo clas tyvars inst_tys theta
- dfun_theta final_dfun_id
+ final_dfun_id
binds src_loc uprags))
\end{code}
\begin{code}
tcInstDecls2 :: Bag InstInfo
- -> NF_TcM s (LIE s, TcMonoBinds s)
+ -> NF_TcM s (LIE, TcMonoBinds)
tcInstDecls2 inst_decls
= foldBag combine tcInstDecl2 (returnNF_Tc (emptyLIE, EmptyMonoBinds)) inst_decls
First comes the easy case of a non-local instance decl.
\begin{code}
-tcInstDecl2 :: InstInfo -> NF_TcM s (LIE s, TcMonoBinds s)
+tcInstDecl2 :: InstInfo -> NF_TcM s (LIE, TcMonoBinds)
tcInstDecl2 (InstInfo clas inst_tyvars inst_tys
- inst_decl_theta dfun_theta
+ inst_decl_theta
dfun_id monobinds
locn uprags)
| not (isLocallyDefined dfun_id)
recoverNF_Tc (returnNF_Tc (emptyLIE, EmptyMonoBinds)) $
tcAddSrcLoc locn $
- -- Get the class signature
- let
- origin = InstanceDeclOrigin
+ -- Instantiate the instance decl with tc-style type variables
+ tcInstId dfun_id `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
+ let
+ (clas, inst_tys') = expectJust "tcInstDecl2" (splitDictTy_maybe dict_ty')
+
+ origin = InstanceDeclOrigin
+
(class_tyvars,
sc_theta, sc_sel_ids,
- op_sel_ids, defm_ids) = classBigSig clas
- in
-
- -- Instantiate the instance decl with tc-style type variables
- tcInstSigTyVars inst_tyvars `thenNF_Tc` \ (inst_tyvars', _, tenv) ->
- mapNF_Tc (tcInstType tenv) inst_tys `thenNF_Tc` \ inst_tys' ->
- tcInstTheta tenv dfun_theta `thenNF_Tc` \ dfun_theta' ->
- tcInstTheta tenv inst_decl_theta `thenNF_Tc` \ inst_decl_theta' ->
+ op_sel_ids, defm_ids) = classBigSig clas
- -- Instantiate the super-class context with inst_tys
- tcInstTheta (zipTyVarEnv class_tyvars inst_tys') sc_theta `thenNF_Tc` \ sc_theta' ->
+ -- Instantiate the theta found in the original instance decl
+ inst_decl_theta' = substTopTheta (zipVarEnv inst_tyvars (mkTyVarTys inst_tyvars'))
+ inst_decl_theta
+ -- Instantiate the super-class context with inst_tys
+ sc_theta' = substTopTheta (zipVarEnv class_tyvars inst_tys') sc_theta
+ in
-- Create dictionary Ids from the specified instance contexts.
newDicts origin sc_theta' `thenNF_Tc` \ (sc_dicts, sc_dict_ids) ->
newDicts origin dfun_theta' `thenNF_Tc` \ (dfun_arg_dicts, dfun_arg_dicts_ids) ->
in
mapNF_Tc check_from_this_class bndrs `thenNF_Tc_`
- tcExtendGlobalValEnv (catMaybes defm_ids) (
-
+ tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
+ tcExtendGlobalValEnv (catMaybes defm_ids) (
-- Default-method Ids may be mentioned in synthesised RHSs
- mapAndUnzip3Tc (tcMethodBind clas origin inst_tys' inst_tyvars' monobinds uprags True)
+
+ mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys' inst_decl_theta'
+ monobinds uprags True)
(op_sel_ids `zip` defm_ids)
- ) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
+ )) `thenTc` \ (method_binds_s, insts_needed_s, meth_lies_w_ids) ->
-- Deal with SPECIALISE instance pragmas
let
) `thenTc` \ (prag_info_fn, prag_binds, prag_lie) ->
-- Check the overloading constraints of the methods and superclasses
- mapNF_Tc zonkSigTyVar inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
+ -- tcMethodBind has checked that the class_tyvars havn't
+ -- been unified with each other or another type, but we must
+ -- still zonk them
+ mapNF_Tc zonkTcTyVarBndr inst_tyvars' `thenNF_Tc` \ zonked_inst_tyvars ->
let
- inst_tyvars_set = mkTyVarSet zonked_inst_tyvars
+ inst_tyvars_set = mkVarSet zonked_inst_tyvars
(meth_lies, meth_ids) = unzip meth_lies_w_ids
inst_tyvars_set -- Local tyvars
inst_decl_dicts -- The instance dictionaries available
sc_dicts -- The superclass dicationaries reqd
- ) `thenTc_`
+ ) `thenTc` \ _ ->
-- Ignore the result; we're only doing
-- this to make sure it can be done.
-- emit an error message. This in turn means that we don't
-- mention the constructor, which doesn't exist for CCallable, CReturnable
-- Hardly beautiful, but only three extra lines.
- HsApp (TyApp (HsVar (RealId eRROR_ID)) [tcIdType this_dict_id])
- (HsLitOut (HsString msg) stringTy)
+ HsApp (TyApp (HsVar eRROR_ID) [idType this_dict_id])
+ (HsLitOut (HsString msg) stringTy)
| otherwise -- The common case
- = foldl HsApp (TyApp (HsVar (RealId dict_constr)) inst_tys')
+ = foldl HsApp (TyApp (HsVar (dataConId dict_constr)) inst_tys')
(map HsVar (sc_dict_ids ++ meth_ids))
-- 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.mkDataConId code rather
+ -- than needing to be repeated here.
+
where
msg = _PK_ ("Compiler error: bad dictionary " ++ showSDoc (ppr clas))
dict_bind = VarMonoBind this_dict_id dict_rhs
- method_binds = andMonoBinds method_binds_s
+ method_binds = andMonoBindList method_binds_s
- final_dfun_id = replaceIdInfo dfun_id (prag_info_fn (idName dfun_id))
+ final_dfun_id = setIdInfo dfun_id (prag_info_fn (idName dfun_id))
-- Pretty truesome
main_bind
= AbsBinds
zonked_inst_tyvars
dfun_arg_dicts_ids
- [(inst_tyvars', RealId final_dfun_id, this_dict_id)]
+ [(inst_tyvars', final_dfun_id, this_dict_id)]
(lie_binds1 `AndMonoBinds`
lie_binds2 `AndMonoBinds`
method_binds `AndMonoBinds`
%* *
%************************************************************************
-@scrutiniseInstanceType@ checks the type {\em and} its syntactic constraints:
+@scrutiniseInstanceHead@ checks the type {\em and} its syntactic constraints:
it must normally look like: @instance Foo (Tycon a b c ...) ...@
The exceptions to this syntactic checking: (1)~if the @GlasgowExts@
We can also have instances for functions: @instance Foo (a -> b) ...@.
\begin{code}
-scrutiniseInstanceType clas inst_taus
+scrutiniseInstanceConstraint (clas, tys)
+ | all isTyVarTy tys
+ || opt_AllowUndecidableInstances = returnNF_Tc ()
+ | otherwise = addErrTc (instConstraintErr clas tys)
+
+scrutiniseInstanceHead clas inst_taus
| -- CCALL CHECK (a).... urgh!
-- To verify that a user declaration of a CCallable/CReturnable
-- instance is OK, we must be able to see the constructor(s)
--
-- We flag this separately to give a more precise error msg.
--
- (uniqueOf clas == cCallableClassKey || uniqueOf clas == cReturnableClassKey)
+ (getUnique clas == cCallableClassKey || getUnique clas == cReturnableClassKey)
&& is_alg_tycon_app && not constructors_visible
- = failWithTc (invisibleDataConPrimCCallErr clas first_inst_tau)
+ = addErrTc (invisibleDataConPrimCCallErr clas first_inst_tau)
| -- CCALL CHECK (b)
-- A user declaration of a CCallable/CReturnable instance
-- must be for a "boxed primitive" type.
- (uniqueOf clas == cCallableClassKey && not (ccallable_type first_inst_tau)) ||
- (uniqueOf clas == cReturnableClassKey && not (creturnable_type first_inst_tau))
- = failWithTc (nonBoxedPrimCCallErr clas first_inst_tau)
+ (getUnique clas == cCallableClassKey && not (ccallable_type first_inst_tau)) ||
+ (getUnique clas == cReturnableClassKey && not (creturnable_type first_inst_tau))
+ = addErrTc (nonBoxedPrimCCallErr clas first_inst_tau)
-- DERIVING CHECK
-- It is obviously illegal to have an explicit instance
-- for something that we are also planning to `derive'
| maybeToBool alg_tycon_app_maybe && clas `elem` (tyConDerivings alg_tycon)
- = failWithTc (derivingWhenInstanceExistsErr clas first_inst_tau)
+ = addErrTc (derivingWhenInstanceExistsErr clas first_inst_tau)
-- Kind check will have ensured inst_taus is of length 1
+ -- Allow anything for AllowUndecidableInstances
+ | opt_AllowUndecidableInstances
+ = returnNF_Tc ()
+
+ -- If GlasgowExts then check at least one isn't a type variable
+ | opt_GlasgowExts
+ = 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 ()
+
-- WITH HASKELL 1.4, MUST HAVE C (T a b c)
- | not opt_GlasgowExts
- && not (length inst_taus == 1 &&
+ | 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 (tyVarSetToList (tyVarsOfTypes arg_tys)) == length arg_tys
+ length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
-- This last condition checks that all the type variables are distinct
)
- = failWithTc (instTypeErr clas inst_taus
+ = 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")
)
| otherwise
- = returnTc ()
+ = returnNF_Tc ()
where
(first_inst_tau : _) = inst_taus
-- These conditions come directly from what the DsCCall is capable of.
-- Totally grotesque. Green card should solve this.
-ccallable_type ty = isUnpointedType ty || -- Allow CCallable Int# etc
+ccallable_type ty = isUnLiftedType ty || -- Allow CCallable Int# etc
maybeToBool (maybeBoxedPrimType ty) || -- Ditto Int etc
ty == stringTy ||
byte_arr_thing
\end{code}
\begin{code}
-
+instConstraintErr clas tys
+ = hang (ptext SLIT("Illegal constaint") <+>
+ quotes (pprConstraint clas tys) <+>
+ ptext SLIT("in instance context"))
+ 4 (ptext SLIT("(Instance contexts must constrain only type variables)"))
+
instTypeErr clas tys msg
= sep [ptext SLIT("Illegal instance declaration for") <+> quotes (pprConstraint clas tys),
nest 4 (parens msg)
projects / ghc-hetmet.git / blobdiff