diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/basicTypes/OccName.hs | 7 | ||||
| -rw-r--r-- | compiler/basicTypes/VarEnv.hs | 9 | ||||
| -rw-r--r-- | compiler/typecheck/TcHsType.hs | 2 | ||||
| -rw-r--r-- | compiler/typecheck/TcMType.hs | 123 | ||||
| -rw-r--r-- | compiler/typecheck/TcPatSyn.hs | 4 | ||||
| -rw-r--r-- | compiler/types/TyCoPpr.hs | 7 | ||||
| -rw-r--r-- | compiler/types/TyCoTidy.hs | 6 | ||||
| -rw-r--r-- | compiler/utils/Outputable.hs | 11 |
8 files changed, 119 insertions, 50 deletions
diff --git a/compiler/basicTypes/OccName.hs b/compiler/basicTypes/OccName.hs index 7584fa4380..ac2ad47100 100644 --- a/compiler/basicTypes/OccName.hs +++ b/compiler/basicTypes/OccName.hs @@ -94,7 +94,7 @@ module OccName ( -- * Tidying up TidyOccEnv, emptyTidyOccEnv, initTidyOccEnv, - tidyOccName, avoidClashesOccEnv, + tidyOccName, avoidClashesOccEnv, delTidyOccEnvList, -- FsEnv FastStringEnv, emptyFsEnv, lookupFsEnv, extendFsEnv, mkFsEnv @@ -818,7 +818,7 @@ Every id contributes a type variable to the type signature, and all of them are (id,id,id) :: (a2 -> a2, a1 -> a1, a -> a) -which is a bit unfortunate, as it unfairly renames only one of them. What we +which is a bit unfortunate, as it unfairly renames only two of them. What we would like to see is (id,id,id) :: (a3 -> a3, a2 -> a2, a1 -> a1) @@ -846,6 +846,9 @@ initTidyOccEnv = foldl' add emptyUFM where add env (OccName _ fs) = addToUFM env fs 1 +delTidyOccEnvList :: TidyOccEnv -> [FastString] -> TidyOccEnv +delTidyOccEnvList = delListFromUFM + -- see Note [Tidying multiple names at once] avoidClashesOccEnv :: TidyOccEnv -> [OccName] -> TidyOccEnv avoidClashesOccEnv env occs = go env emptyUFM occs diff --git a/compiler/basicTypes/VarEnv.hs b/compiler/basicTypes/VarEnv.hs index 4c23b1f141..dfdc933b67 100644 --- a/compiler/basicTypes/VarEnv.hs +++ b/compiler/basicTypes/VarEnv.hs @@ -71,13 +71,14 @@ module VarEnv ( -- * TidyEnv and its operation TidyEnv, - emptyTidyEnv, mkEmptyTidyEnv + emptyTidyEnv, mkEmptyTidyEnv, delTidyEnvList ) where import GhcPrelude import qualified Data.IntMap.Strict as IntMap -- TODO: Move this to UniqFM import OccName +import Name import Var import VarSet import UniqSet @@ -424,6 +425,12 @@ emptyTidyEnv = (emptyTidyOccEnv, emptyVarEnv) mkEmptyTidyEnv :: TidyOccEnv -> TidyEnv mkEmptyTidyEnv occ_env = (occ_env, emptyVarEnv) +delTidyEnvList :: TidyEnv -> [Var] -> TidyEnv +delTidyEnvList (occ_env, var_env) vs = (occ_env', var_env') + where + occ_env' = occ_env `delTidyOccEnvList` map (occNameFS . getOccName) vs + var_env' = var_env `delVarEnvList` vs + {- ************************************************************************ * * diff --git a/compiler/typecheck/TcHsType.hs b/compiler/typecheck/TcHsType.hs index 17c027318b..61980788cd 100644 --- a/compiler/typecheck/TcHsType.hs +++ b/compiler/typecheck/TcHsType.hs @@ -1770,7 +1770,7 @@ the surrounding context, we must obey the following dictum: Every metavariable in a type must either be (A) generalized, or (B) promoted, or See Note [Promotion in signatures] - (C) zapped to Any See Note [Naughty quantification candidates] in TcMType + (C) a cause to error See Note [Naughty quantification candidates] in TcMType The kindGeneralize functions do not require pre-zonking; they zonk as they go. diff --git a/compiler/typecheck/TcMType.hs b/compiler/typecheck/TcMType.hs index 0ac553c0ea..c86e3162c0 100644 --- a/compiler/typecheck/TcMType.hs +++ b/compiler/typecheck/TcMType.hs @@ -1137,8 +1137,7 @@ So alpha is entirely unconstrained. What then should we do with alpha? During generalization, every metavariable is either (A) promoted, (B) generalized, or (C) zapped -(according again to Note [Recipe for checking a signature] in -TcHsType). +(according to Note [Recipe for checking a signature] in TcHsType). * We can't generalise it. * We can't promote it, because its kind prevents that @@ -1146,11 +1145,14 @@ TcHsType). go into the typing environment (as the type of some let-bound variable, say), and then chaos erupts when we try to instantiate. -So, we zap it, eagerly, to Any. We don't have to do this eager zapping -in terms (say, in `length []`) because terms are never re-examined before -the final zonk (which zaps any lingering metavariables to Any). +Previously, we zapped it to Any. This worked, but it had the unfortunate +effect of causing Any sometimes to appear in error messages. If this +kind of signature happens, the user probably has made a mistake -- no +one really wants Any in their types. So we now error. This must be +a hard error (failure in the monad) to avoid other messages from mentioning +Any. -We do this eager zapping in candidateQTyVars, which always precedes +We do this eager erroring in candidateQTyVars, which always precedes generalisation, because at that moment we have a clear picture of what skolems are in scope within the type itself (e.g. that 'forall arg'). @@ -1235,13 +1237,14 @@ partitionCandidates dvs@(DV { dv_kvs = kvs, dv_tvs = tvs }) pred -- See Note [Dependent type variables] candidateQTyVarsOfType :: TcType -- not necessarily zonked -> TcM CandidatesQTvs -candidateQTyVarsOfType ty = collect_cand_qtvs False emptyVarSet mempty ty +candidateQTyVarsOfType ty = collect_cand_qtvs ty False emptyVarSet mempty ty -- | Like 'candidateQTyVarsOfType', but over a list of types -- The variables to quantify must have a TcLevel strictly greater than -- the ambient level. (See Wrinkle in Note [Naughty quantification candidates]) candidateQTyVarsOfTypes :: [Type] -> TcM CandidatesQTvs -candidateQTyVarsOfTypes tys = foldlM (collect_cand_qtvs False emptyVarSet) mempty tys +candidateQTyVarsOfTypes tys = foldlM (\acc ty -> collect_cand_qtvs ty False emptyVarSet acc ty) + mempty tys -- | Like 'candidateQTyVarsOfType', but consider every free variable -- to be dependent. This is appropriate when generalizing a *kind*, @@ -1249,11 +1252,12 @@ candidateQTyVarsOfTypes tys = foldlM (collect_cand_qtvs False emptyVarSet) mempt -- to Type.) candidateQTyVarsOfKind :: TcKind -- Not necessarily zonked -> TcM CandidatesQTvs -candidateQTyVarsOfKind ty = collect_cand_qtvs True emptyVarSet mempty ty +candidateQTyVarsOfKind ty = collect_cand_qtvs ty True emptyVarSet mempty ty candidateQTyVarsOfKinds :: [TcKind] -- Not necessarily zonked -> TcM CandidatesQTvs -candidateQTyVarsOfKinds tys = foldM (collect_cand_qtvs True emptyVarSet) mempty tys +candidateQTyVarsOfKinds tys = foldM (\acc ty -> collect_cand_qtvs ty True emptyVarSet acc ty) + mempty tys delCandidates :: CandidatesQTvs -> [Var] -> CandidatesQTvs delCandidates (DV { dv_kvs = kvs, dv_tvs = tvs, dv_cvs = cvs }) vars @@ -1262,7 +1266,8 @@ delCandidates (DV { dv_kvs = kvs, dv_tvs = tvs, dv_cvs = cvs }) vars , dv_cvs = cvs `delVarSetList` vars } collect_cand_qtvs - :: Bool -- True <=> consider every fv in Type to be dependent + :: TcType -- original type that we started recurring into; for errors + -> Bool -- True <=> consider every fv in Type to be dependent -> VarSet -- Bound variables (locals only) -> CandidatesQTvs -- Accumulating parameter -> Type -- Not necessarily zonked @@ -1272,14 +1277,14 @@ collect_cand_qtvs -- * Looks through meta-tyvars as it goes; -- no need to zonk in advance -- --- * Needs to be monadic anyway, because it does the zap-naughty --- stuff; see Note [Naughty quantification candidates] +-- * Needs to be monadic anyway, because it handles naughty +-- quantification; see Note [Naughty quantification candidates] -- -- * Returns fully-zonked CandidateQTvs, including their kinds -- so that subsequent dependency analysis (to build a well -- scoped telescope) works correctly -collect_cand_qtvs is_dep bound dvs ty +collect_cand_qtvs orig_ty is_dep bound dvs ty = go dvs ty where is_bound tv = tv `elemVarSet` bound @@ -1292,8 +1297,8 @@ collect_cand_qtvs is_dep bound dvs ty go dv (FunTy _ arg res) = foldlM go dv [arg, res] go dv (LitTy {}) = return dv go dv (CastTy ty co) = do dv1 <- go dv ty - collect_cand_qtvs_co bound dv1 co - go dv (CoercionTy co) = collect_cand_qtvs_co bound dv co + collect_cand_qtvs_co orig_ty bound dv1 co + go dv (CoercionTy co) = collect_cand_qtvs_co orig_ty bound dv co go dv (TyVarTy tv) | is_bound tv = return dv @@ -1303,8 +1308,8 @@ collect_cand_qtvs is_dep bound dvs ty Nothing -> go_tv dv tv } go dv (ForAllTy (Bndr tv _) ty) - = do { dv1 <- collect_cand_qtvs True bound dv (tyVarKind tv) - ; collect_cand_qtvs is_dep (bound `extendVarSet` tv) dv1 ty } + = do { dv1 <- collect_cand_qtvs orig_ty True bound dv (tyVarKind tv) + ; collect_cand_qtvs orig_ty is_dep (bound `extendVarSet` tv) dv1 ty } ----------------- go_tv dv@(DV { dv_kvs = kvs, dv_tvs = tvs }) tv @@ -1322,25 +1327,23 @@ collect_cand_qtvs is_dep bound dvs ty -- (#15795) and to make the naughty check -- (which comes next) works correctly + ; let tv_kind_vars = tyCoVarsOfType tv_kind ; cur_lvl <- getTcLevel ; if | tcTyVarLevel tv <= cur_lvl -> return dv -- this variable is from an outer context; skip -- See Note [Use level numbers ofor quantification] - | intersectsVarSet bound (tyCoVarsOfType tv_kind) + | intersectsVarSet bound tv_kind_vars -- the tyvar must not be from an outer context, but we have -- already checked for this. -- See Note [Naughty quantification candidates] - -> do { traceTc "Zapping naughty quantifier" $ + -> do { traceTc "Naughty quantifier" $ vcat [ ppr tv <+> dcolon <+> ppr tv_kind , text "bound:" <+> pprTyVars (nonDetEltsUniqSet bound) - , text "fvs:" <+> pprTyVars (nonDetEltsUniqSet $ - tyCoVarsOfType tv_kind) ] + , text "fvs:" <+> pprTyVars (nonDetEltsUniqSet tv_kind_vars) ] - ; writeMetaTyVar tv (anyTypeOfKind tv_kind) - - -- See Note [Recurring into kinds for candidateQTyVars] - ; collect_cand_qtvs True bound dv tv_kind } + ; let escapees = intersectVarSet bound tv_kind_vars + ; naughtyQuantification orig_ty tv escapees } | otherwise -> do { let tv' = tv `setTyVarKind` tv_kind @@ -1349,15 +1352,16 @@ collect_cand_qtvs is_dep bound dvs ty -- See Note [Order of accumulation] -- See Note [Recurring into kinds for candidateQTyVars] - ; collect_cand_qtvs True bound dv' tv_kind } } + ; collect_cand_qtvs orig_ty True bound dv' tv_kind } } -collect_cand_qtvs_co :: VarSet -- bound variables +collect_cand_qtvs_co :: TcType -- original type at top of recursion; for errors + -> VarSet -- bound variables -> CandidatesQTvs -> Coercion -> TcM CandidatesQTvs -collect_cand_qtvs_co bound = go_co +collect_cand_qtvs_co orig_ty bound = go_co where - go_co dv (Refl ty) = collect_cand_qtvs True bound dv ty - go_co dv (GRefl _ ty mco) = do dv1 <- collect_cand_qtvs True bound dv ty + go_co dv (Refl ty) = collect_cand_qtvs orig_ty True bound dv ty + go_co dv (GRefl _ ty mco) = do dv1 <- collect_cand_qtvs orig_ty True bound dv ty go_mco dv1 mco go_co dv (TyConAppCo _ _ cos) = foldlM go_co dv cos go_co dv (AppCo co1 co2) = foldlM go_co dv [co1, co2] @@ -1365,8 +1369,8 @@ collect_cand_qtvs_co bound = go_co go_co dv (AxiomInstCo _ _ cos) = foldlM go_co dv cos go_co dv (AxiomRuleCo _ cos) = foldlM go_co dv cos go_co dv (UnivCo prov _ t1 t2) = do dv1 <- go_prov dv prov - dv2 <- collect_cand_qtvs True bound dv1 t1 - collect_cand_qtvs True bound dv2 t2 + dv2 <- collect_cand_qtvs orig_ty True bound dv1 t1 + collect_cand_qtvs orig_ty True bound dv2 t2 go_co dv (SymCo co) = go_co dv co go_co dv (TransCo co1 co2) = foldlM go_co dv [co1, co2] go_co dv (NthCo _ _ co) = go_co dv co @@ -1385,7 +1389,7 @@ collect_cand_qtvs_co bound = go_co go_co dv (ForAllCo tcv kind_co co) = do { dv1 <- go_co dv kind_co - ; collect_cand_qtvs_co (bound `extendVarSet` tcv) dv1 co } + ; collect_cand_qtvs_co orig_ty (bound `extendVarSet` tcv) dv1 co } go_mco dv MRefl = return dv go_mco dv (MCo co) = go_co dv co @@ -1401,7 +1405,7 @@ collect_cand_qtvs_co bound = go_co | cv `elemVarSet` cvs = return dv -- See Note [Recurring into kinds for candidateQTyVars] - | otherwise = collect_cand_qtvs True bound + | otherwise = collect_cand_qtvs orig_ty True bound (dv { dv_cvs = cvs `extendVarSet` cv }) (idType cv) @@ -2305,8 +2309,8 @@ tidySigSkol env cx ty tv_prs %************************************************************************ %* * Levity polymorphism checks -* * -************************************************************************ +* * +************************************************************************* See Note [Levity polymorphism checking] in DsMonad @@ -2351,3 +2355,48 @@ formatLevPolyErr ty where (tidy_env, tidy_ty) = tidyOpenType emptyTidyEnv ty tidy_ki = tidyType tidy_env (tcTypeKind ty) + +{- +%************************************************************************ +%* * + Error messages +* * +************************************************************************* + +-} + +-- See Note [Naughty quantification candidates] +naughtyQuantification :: TcType -- original type user wanted to quantify + -> TcTyVar -- naughty var + -> TyVarSet -- skolems that would escape + -> TcM a +naughtyQuantification orig_ty tv escapees + = do { orig_ty1 <- zonkTcType orig_ty -- in case it's not zonked + + ; escapees' <- mapM zonkTcTyVarToTyVar $ + nonDetEltsUniqSet escapees + -- we'll just be printing, so no harmful non-determinism + + ; let fvs = tyCoVarsOfTypeWellScoped orig_ty1 + env0 = tidyFreeTyCoVars emptyTidyEnv fvs + env = env0 `delTidyEnvList` escapees' + -- this avoids gratuitous renaming of the escaped + -- variables; very confusing to users! + + orig_ty' = tidyType env orig_ty1 + ppr_tidied = pprTyVars . map (tidyTyCoVarOcc env) + doc = pprWithExplicitKindsWhen True $ + vcat [ sep [ text "Cannot generalise type; skolem" <> plural escapees' + , quotes $ ppr_tidied escapees' + , text "would escape" <+> itsOrTheir escapees' <+> text "scope" + ] + , sep [ text "if I tried to quantify" + , ppr_tidied [tv] + , text "in this type:" + ] + , nest 2 (pprTidiedType orig_ty') + , text "(Indeed, I sometimes struggle even printing this correctly," + , text " due to its ill-scoped nature.)" + ] + + ; failWithTcM (env, doc) } diff --git a/compiler/typecheck/TcPatSyn.hs b/compiler/typecheck/TcPatSyn.hs index 1a6d3ea1e4..6984d06907 100644 --- a/compiler/typecheck/TcPatSyn.hs +++ b/compiler/typecheck/TcPatSyn.hs @@ -237,7 +237,7 @@ dependentArgErr (arg, bad_cos) ~~-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider data AST a = Sym [a] - class Prj s where { prj :: [a] -> Maybe (s a) + class Prj s where { prj :: [a] -> Maybe (s a) } pattern P x <= Sym (prj -> Just x) Here we get a matcher with this type @@ -261,7 +261,7 @@ mentions the existentials. We can conveniently do that by making the forall ex_tvs. arg_ty After that, Note [Naughty quantification candidates] in TcMType takes -over, and zonks any such naughty variables to Any. +over and errors. Note [Remove redundant provided dicts] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/compiler/types/TyCoPpr.hs b/compiler/types/TyCoPpr.hs index fbbdfbd7a0..f7a768210b 100644 --- a/compiler/types/TyCoPpr.hs +++ b/compiler/types/TyCoPpr.hs @@ -5,7 +5,7 @@ module TyCoPpr PprPrec(..), topPrec, sigPrec, opPrec, funPrec, appPrec, maybeParen, -- * Pretty-printing types - pprType, pprParendType, pprPrecType, pprPrecTypeX, + pprType, pprParendType, pprTidiedType, pprPrecType, pprPrecTypeX, pprTypeApp, pprTCvBndr, pprTCvBndrs, pprSigmaType, pprTheta, pprParendTheta, pprForAll, pprUserForAll, @@ -81,10 +81,13 @@ See Note [Precedence in types] in BasicTypes. -- See Note [Pretty printing via Iface syntax] in PprTyThing -------------------------------------------------------- -pprType, pprParendType :: Type -> SDoc +pprType, pprParendType, pprTidiedType :: Type -> SDoc pprType = pprPrecType topPrec pprParendType = pprPrecType appPrec +-- already pre-tidied +pprTidiedType = pprIfaceType . toIfaceTypeX emptyVarSet + pprPrecType :: PprPrec -> Type -> SDoc pprPrecType = pprPrecTypeX emptyTidyEnv diff --git a/compiler/types/TyCoTidy.hs b/compiler/types/TyCoTidy.hs index f4639ca303..b6f87c2230 100644 --- a/compiler/types/TyCoTidy.hs +++ b/compiler/types/TyCoTidy.hs @@ -95,8 +95,8 @@ tidyTyCoVarBinders tidy_env tvbs tidyFreeTyCoVars :: TidyEnv -> [TyCoVar] -> TidyEnv -- ^ Add the free 'TyVar's to the env in tidy form, -- so that we can tidy the type they are free in -tidyFreeTyCoVars (full_occ_env, var_env) tyvars - = fst (tidyOpenTyCoVars (full_occ_env, var_env) tyvars) +tidyFreeTyCoVars tidy_env tyvars + = fst (tidyOpenTyCoVars tidy_env tyvars) --------------- tidyOpenTyCoVars :: TidyEnv -> [TyCoVar] -> (TidyEnv, [TyCoVar]) @@ -232,5 +232,3 @@ tidyCo env@(_, subst) co tidyCos :: TidyEnv -> [Coercion] -> [Coercion] tidyCos env = map (tidyCo env) - - diff --git a/compiler/utils/Outputable.hs b/compiler/utils/Outputable.hs index d81c754866..02805c6c7c 100644 --- a/compiler/utils/Outputable.hs +++ b/compiler/utils/Outputable.hs @@ -34,7 +34,7 @@ module Outputable ( sep, cat, fsep, fcat, hang, hangNotEmpty, punctuate, ppWhen, ppUnless, - speakNth, speakN, speakNOf, plural, isOrAre, doOrDoes, + speakNth, speakN, speakNOf, plural, isOrAre, doOrDoes, itsOrTheir, unicodeSyntax, coloured, keyword, @@ -1160,6 +1160,15 @@ doOrDoes :: [a] -> SDoc doOrDoes [_] = text "does" doOrDoes _ = text "do" +-- | Determines the form of possessive appropriate for the length of a list: +-- +-- > itsOrTheir [x] = text "its" +-- > itsOrTheir [x,y] = text "their" +-- > itsOrTheir [] = text "their" -- probably avoid this +itsOrTheir :: [a] -> SDoc +itsOrTheir [_] = text "its" +itsOrTheir _ = text "their" + {- ************************************************************************ * * |