#include "HsVersions.h"
-import CmdLineOpts ( DynFlag(..), dopt )
+import CmdLineOpts ( DynFlag(..) )
import HsSyn ( HsDecl(..), InstDecl(..), TyClDecl(..), HsType(..),
MonoBinds(..), HsExpr(..), HsLit(..), Sig(..), HsTyVarBndr(..),
import TcBinds ( tcSpecSigs )
import TcClassDcl ( tcMethodBind, badMethodErr )
import TcMonad
-import TcType ( tcInstType )
+import TcMType ( tcInstSigTyVars, checkValidTheta, checkValidInstHead, instTypeErr,
+ UserTypeCtxt(..), SourceTyCtxt(..) )
+import TcType ( tcSplitDFunTy, mkClassPred, mkTyVarTy, mkTyVarTys,
+ tcSplitSigmaTy, tcSplitPredTy_maybe, getClassPredTys,
+ TyVarDetails(..)
+ )
import Inst ( InstOrigin(..),
newDicts, instToId,
LIE, mkLIE, emptyLIE, plusLIE, plusLIEs )
tcExtendTyVarEnvForMeths,
tcAddImportedIdInfo, tcLookupClass,
InstInfo(..), pprInstInfo, simpleInstInfoTyCon,
- simpleInstInfoTy, newDFunName, tcExtendTyVarEnv,
+ simpleInstInfoTy, newDFunName,
isLocalThing,
)
import InstEnv ( InstEnv, extendInstEnv )
-import TcMonoType ( tcHsTyVars, tcHsSigType, kcHsSigType, checkSigTyVars )
+import PprType ( pprClassPred )
+import TcMonoType ( tcHsTyVars, kcHsSigType, tcHsType, tcHsSigType, checkSigTyVars )
import TcSimplify ( tcSimplifyCheck )
import HscTypes ( HomeSymbolTable, DFunId,
ModDetails(..), PackageInstEnv, PersistentRenamerState
)
+import Subst ( substTy, substTheta )
import DataCon ( classDataCon )
import Class ( Class, DefMeth(..), classBigSig )
import Var ( idName, idType )
import VarSet ( emptyVarSet )
-import Maybes ( maybeToBool )
+import Id ( setIdLocalExported )
import MkId ( mkDictFunId )
import FunDeps ( checkInstFDs )
import Generics ( validGenericInstanceType )
import Module ( Module, foldModuleEnv )
import Name ( getSrcLoc )
-import NameSet ( emptyNameSet, unitNameSet, nameSetToList )
+import NameSet ( unitNameSet, emptyNameSet, nameSetToList )
import PrelInfo ( eRROR_ID )
-import PprType ( pprClassPred, pprPred )
-import TyCon ( TyCon, isSynTyCon )
-import Type ( splitDFunTy, isTyVarTy,
- splitTyConApp_maybe, splitDictTy,
- splitForAllTys,
- tyVarsOfTypes, mkClassPred, mkTyVarTy,
- isTyVarClassPred, inheritablePred
- )
+import TyCon ( TyCon )
import Subst ( mkTopTyVarSubst, substTheta )
-import VarSet ( varSetElems )
-import TysWiredIn ( genericTyCons, isFFIArgumentTy, isFFIImportResultTy )
-import PrelNames ( cCallableClassKey, cReturnableClassKey, hasKey )
+import TysWiredIn ( genericTyCons )
import Name ( Name )
import SrcLoc ( SrcLoc )
-import VarSet ( varSetElems )
import Unique ( Uniquable(..) )
+import Util ( lengthExceeds )
import BasicTypes ( NewOrData(..), Fixity )
import ErrUtils ( dumpIfSet_dyn )
import ListSetOps ( Assoc, emptyAssoc, plusAssoc_C, mapAssoc,
imported_dfuns = map (tcAddImportedIdInfo unf_env . iDFunId)
imported_inst_info
hst_dfuns = foldModuleEnv ((++) . md_insts) [] hst
- in
+ in
+
+-- pprTrace "tcInstDecls" (vcat [ppr imported_dfuns, ppr hst_dfuns]) $
+
addInstDFuns inst_env0 imported_dfuns `thenNF_Tc` \ inst_env1 ->
addInstDFuns inst_env1 hst_dfuns `thenNF_Tc` \ inst_env2 ->
addInstInfos inst_env2 local_inst_info `thenNF_Tc` \ inst_env3 ->
addInstInfos inst_env infos = addInstDFuns inst_env (map iDFunId infos)
addInstDFuns :: InstEnv -> [DFunId] -> NF_TcM InstEnv
-addInstDFuns dfuns infos
+addInstDFuns inst_env dfuns
= getDOptsTc `thenTc` \ dflags ->
let
- (inst_env', errs) = extendInstEnv dflags dfuns infos
+ (inst_env', errs) = extendInstEnv dflags inst_env dfuns
in
addErrsTc errs `thenNF_Tc_`
+ traceTc (text "Adding instances:" <+> vcat (map pp dfuns)) `thenTc_`
returnTc inst_env'
+ where
+ pp dfun = ppr dfun <+> dcolon <+> ppr (idType dfun)
\end{code}
\begin{code}
tcInstDecl1 :: RenamedInstDecl -> NF_TcM [InstInfo]
-- Deal with a single instance declaration
+-- Type-check all the stuff before the "where"
tcInstDecl1 decl@(InstDecl poly_ty binds uprags maybe_dfun_name src_loc)
= -- Prime error recovery, set source location
recoverNF_Tc (returnNF_Tc []) $
tcAddSrcLoc src_loc $
+ tcAddErrCtxt (instDeclCtxt poly_ty) $
- -- Type-check all the stuff before the "where"
- tcAddErrCtxt (instDeclCtxt poly_ty) (
- tcHsSigType poly_ty
- ) `thenTc` \ poly_ty' ->
+ -- Typecheck the instance type itself. We can't use
+ -- tcHsSigType, because it's not a valid user type.
+ kcHsSigType poly_ty `thenTc_`
+ tcHsType poly_ty `thenTc` \ poly_ty' ->
let
- (tyvars, theta, clas, inst_tys) = splitDFunTy poly_ty'
+ (tyvars, theta, tau) = tcSplitSigmaTy poly_ty'
+ (clas,inst_tys) = case tcSplitPredTy_maybe tau of { Just st -> getClassPredTys st }
+ -- The checkValidInstHead makes sure these splits succeed
in
-
(case maybe_dfun_name of
Nothing -> -- A source-file instance declaration
-
-- 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]
- 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 ->
- returnNF_Tc (True, dfun_name)
+ checkValidTheta InstThetaCtxt theta `thenTc_`
+ checkValidInstHead tau `thenTc_`
+ checkTc (checkInstFDs theta clas inst_tys)
+ (instTypeErr (pprClassPred clas inst_tys) msg) `thenTc_`
+ newDFunName clas inst_tys src_loc
Just dfun_name -> -- An interface-file instance declaration
- -- Make the dfun id
- returnNF_Tc (False, dfun_name)
- ) `thenNF_Tc` \ (is_local, dfun_name) ->
-
+ returnNF_Tc dfun_name
+ ) `thenNF_Tc` \ dfun_name ->
let
dfun_id = mkDictFunId dfun_name clas tyvars inst_tys theta
in
- returnTc [InstInfo { iDFunId = dfun_id,
- iBinds = binds, iPrags = uprags }]
+ returnTc [InstInfo { iDFunId = dfun_id, iBinds = binds, iPrags = uprags }]
+ where
+ msg = parens (ptext SLIT("the instance types do not agree with the functional dependencies of the class"))
\end{code}
| null groups
= returnTc [] -- The comon case: no generic default methods
- | otherwise -- A local class decl with generic default methods
+ | otherwise -- A source class decl with generic default methods
= recoverNF_Tc (returnNF_Tc []) $
tcAddDeclCtxt decl $
tcLookupClass class_name `thenTc` \ clas ->
tc_inst_infos = [(simpleInstInfoTyCon i, i) | i <- inst_infos]
bad_groups = [group | group <- equivClassesByUniq get_uniq tc_inst_infos,
- length group > 1]
+ group `lengthExceeds` 1]
get_uniq (tc,_) = getUnique tc
in
mapTc (addErrTc . dupGenericInsts) bad_groups `thenTc_`
tcHsTyVars sig_tvs (kcHsSigType hs_ty) $ \ tyvars ->
-- Type-check the instance type, and check its form
- tcHsSigType hs_ty `thenTc` \ inst_ty ->
+ tcHsSigType GenPatCtxt hs_ty `thenTc` \ inst_ty ->
checkTc (validGenericInstanceType inst_ty)
(badGenericInstanceType binds) `thenTc_`
tcAddErrCtxt (instDeclCtxt (toHsType (idType dfun_id))) $
-- Instantiate the instance decl with tc-style type variables
- tcInstType (idType dfun_id) `thenNF_Tc` \ (inst_tyvars', dfun_theta', dict_ty') ->
let
- (clas, inst_tys') = splitDictTy dict_ty'
- origin = InstanceDeclOrigin
+ (inst_tyvars, dfun_theta, clas, inst_tys) = tcSplitDFunTy (idType dfun_id)
+ in
+ tcInstSigTyVars InstTv inst_tyvars `thenNF_Tc` \ inst_tyvars' ->
+ let
+ tenv = mkTopTyVarSubst inst_tyvars (mkTyVarTys inst_tyvars')
+ inst_tys' = map (substTy tenv) inst_tys
+ dfun_theta' = substTheta tenv dfun_theta
+ origin = InstanceDeclOrigin
(class_tyvars, sc_theta, _, op_items) = classBigSig clas
- dm_ids = [dm_id | (_, DefMeth dm_id) <- op_items]
sel_names = [idName sel_id | (sel_id, _) <- op_items]
-- Instantiate the super-class context with inst_tys
-- Find any definitions in monobinds that aren't from the class
bad_bndrs = collectMonoBinders monobinds `minusList` sel_names
-
- -- The type variable from the dict fun actually scope
- -- over the bindings. They were gotten from
- -- the original instance declaration
- (inst_tyvars, _) = splitForAllTys (idType dfun_id)
in
-- Check that all the method bindings come from this class
mapTc (addErrTc . badMethodErr clas) bad_bndrs `thenNF_Tc_`
newDicts origin [mkClassPred clas inst_tys'] `thenNF_Tc` \ [this_dict] ->
tcExtendTyVarEnvForMeths inst_tyvars inst_tyvars' (
- tcExtendGlobalValEnv dm_ids (
- -- Default-method Ids may be mentioned in synthesised RHSs
+ -- The type variable from the dict fun actually scope
+ -- over the bindings. They were gotten from
+ -- the original instance declaration
+
+ -- Default-method Ids may be mentioned in synthesised RHSs,
+ -- but they'll already be in the environment.
mapAndUnzip3Tc (tcMethodBind clas origin inst_tyvars' inst_tys'
dfun_theta'
monobinds uprags True)
op_items
- )) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) ->
+ ) `thenTc` \ (method_binds_s, insts_needed_s, meth_insts) ->
-- Deal with SPECIALISE instance pragmas by making them
-- look like SPECIALISE pragmas for the dfun
-- Create the result bindings
let
+ local_dfun_id = setIdLocalExported dfun_id
+ -- Reason for setIdLocalExported: see notes with MkId.mkDictFunId
+
dict_constr = classDataCon clas
scs_and_meths = map instToId (sc_dicts ++ meth_insts)
this_dict_id = instToId this_dict
- inlines = unitNameSet (idName dfun_id)
+ inlines | null dfun_arg_dicts = emptyNameSet
+ | otherwise = unitNameSet (idName dfun_id)
-- 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
dict_rhs
| null scs_and_meths
= AbsBinds
zonked_inst_tyvars
(map instToId dfun_arg_dicts)
- [(inst_tyvars', dfun_id, this_dict_id)]
+ [(inst_tyvars', local_dfun_id, this_dict_id)]
inlines
(lie_binds1 `AndMonoBinds`
lie_binds2 `AndMonoBinds`
%************************************************************************
%* *
-\subsection{Checking for a decent instance type}
-%* *
-%************************************************************************
-
-@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@
-flag is on, or (2)~the instance is imported (they must have been
-compiled elsewhere). In these cases, we let them go through anyway.
-
-We can also have instances for functions: @instance Foo (a -> b) ...@.
-
-\begin{code}
-checkInstValidity dflags theta clas inst_tys
- | null errs = returnTc ()
- | otherwise = addErrsTc errs `thenNF_Tc_` failTc
- where
- errs = checkInstHead dflags theta clas inst_tys ++
- [err | pred <- theta, err <- checkInstConstraint dflags pred]
-
-checkInstConstraint dflags pred
- -- Checks whether a predicate is legal in the
- -- context of an instance declaration
- | ok = []
- | otherwise = [instConstraintErr pred]
- where
- ok = inheritablePred pred &&
- (isTyVarClassPred pred || arbitrary_preds_ok)
-
- arbitrary_preds_ok = dopt Opt_AllowUndecidableInstances dflags
-
-
-checkInstHead dflags theta clas inst_taus
- | -- CCALL CHECK
- -- A user declaration of a CCallable/CReturnable instance
- -- must be for a "boxed primitive" type.
- (clas `hasKey` cCallableClassKey
- && not (ccallable_type dflags first_inst_tau))
- ||
- (clas `hasKey` cReturnableClassKey
- && not (creturnable_type first_inst_tau))
- = [nonBoxedPrimCCallErr clas first_inst_tau]
-
- -- If GlasgowExts then check at least one isn't a type variable
- | dopt Opt_GlasgowExts dflags
- = -- GlasgowExts case
- check_tyvars dflags clas inst_taus ++ check_fundeps dflags theta 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
- -- This last condition checks that all the type variables are distinct
- )
- = [instTypeErr clas inst_taus
- (text "the instance type must be of form (T a b c)" $$
- text "where T is not a synonym, and a,b,c are distinct type variables")]
-
- | otherwise
- = []
-
- where
- (first_inst_tau : _) = inst_taus
-
- -- Stuff for algebraic or -> type
- maybe_tycon_app = splitTyConApp_maybe first_inst_tau
- Just (tycon, arg_tys) = maybe_tycon_app
-
- ccallable_type dflags ty = isFFIArgumentTy dflags False {- Not safe call -} ty
- creturnable_type ty = isFFIImportResultTy dflags ty
-
-check_tyvars dflags clas inst_taus
- -- Check that at least one isn't a type variable
- -- unless -fallow-undecideable-instances
- | dopt Opt_AllowUndecidableInstances dflags = []
- | not (all isTyVarTy inst_taus) = []
- | otherwise = [the_err]
- where
- the_err = instTypeErr clas inst_taus msg
- msg = ptext SLIT("There must be at least one non-type-variable in the instance head")
- $$ ptext SLIT("Use -fallow-undecidable-instances to lift this restriction")
-
-check_fundeps dflags theta clas inst_taus
- | checkInstFDs theta 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}
-
-
-%************************************************************************
-%* *
\subsection{Error messages}
%* *
%************************************************************************
\end{code}
\begin{code}
-instConstraintErr pred
- = hang (ptext SLIT("Illegal constraint") <+>
- quotes (pprPred pred) <+>
- ptext SLIT("in instance context"))
- 4 (ptext SLIT("(Instance contexts must constrain only type variables)"))
-
badGenericInstanceType binds
= vcat [ptext SLIT("Illegal type pattern in the generic bindings"),
nest 4 (ppr binds)]
missingGenericInstances missing
= ptext SLIT("Missing type patterns for") <+> pprQuotedList missing
-
-
dupGenericInsts tc_inst_infos
= vcat [ptext SLIT("More than one type pattern for a single generic type constructor:"),
nest 4 (vcat (map ppr_inst_ty tc_inst_infos)),
where
ppr_inst_ty (tc,inst) = ppr (simpleInstInfoTy inst)
-instTypeErr clas tys msg
- = 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 (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")
\end{code}
projects / ghc-hetmet.git / blobdiff