{-# LANGUAGE BangPatterns #-} {-# LANGUAGE ExplicitForAll #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE RecordWildCards #-} {-# OPTIONS_GHC -fno-warn-orphans #-} {-# OPTIONS_GHC -Wno-incomplete-record-updates #-} {- (c) The University of Glasgow 2006 -} -- | Functions for working with the typechecker environment (setters, -- getters...). module GHC.Tc.Utils.Monad( -- * Initialisation initTc, initTcWithGbl, initTcInteractive, initTcRnIf, -- * Simple accessors discardResult, getTopEnv, updTopEnv, getGblEnv, updGblEnv, setGblEnv, getLclEnv, updLclEnv, setLclEnv, restoreLclEnv, updTopFlags, getEnvs, setEnvs, updEnvs, restoreEnvs, xoptM, doptM, goptM, woptM, setXOptM, unsetXOptM, unsetGOptM, unsetWOptM, whenDOptM, whenGOptM, whenWOptM, whenXOptM, unlessXOptM, getGhcMode, withoutDynamicNow, getEpsVar, getEps, updateEps, updateEps_, getHpt, getEpsAndHug, -- * Arrow scopes newArrowScope, escapeArrowScope, -- * Unique supply newUnique, newUniqueSupply, newName, newNameAt, cloneLocalName, newSysName, newSysLocalId, newSysLocalIds, -- * Accessing input/output newTcRef, readTcRef, writeTcRef, updTcRef, -- * Debugging traceTc, traceRn, traceOptTcRn, dumpOptTcRn, dumpTcRn, getPrintUnqualified, printForUserTcRn, traceIf, traceOptIf, debugTc, -- * Typechecker global environment getIsGHCi, getGHCiMonad, getInteractivePrintName, tcIsHsBootOrSig, tcIsHsig, tcSelfBootInfo, getGlobalRdrEnv, getRdrEnvs, getImports, getFixityEnv, extendFixityEnv, getRecFieldEnv, getDeclaredDefaultTys, addDependentFiles, -- * Error management getSrcSpanM, setSrcSpan, setSrcSpanA, addLocM, addLocMA, inGeneratedCode, wrapLocM, wrapLocAM, wrapLocFstM, wrapLocFstMA, wrapLocSndM, wrapLocSndMA, wrapLocM_, wrapLocMA_,wrapLocMA, getErrsVar, setErrsVar, addErr, failWith, failAt, addErrAt, addErrs, checkErr, addMessages, discardWarnings, -- * Usage environment tcCollectingUsage, tcScalingUsage, tcEmitBindingUsage, -- * Shared error message stuff: renamer and typechecker recoverM, mapAndRecoverM, mapAndReportM, foldAndRecoverM, attemptM, tryTc, askNoErrs, discardErrs, tryTcDiscardingErrs, checkNoErrs, whenNoErrs, ifErrsM, failIfErrsM, -- * Context management for the type checker getErrCtxt, setErrCtxt, addErrCtxt, addErrCtxtM, addLandmarkErrCtxt, addLandmarkErrCtxtM, popErrCtxt, getCtLocM, setCtLocM, -- * Diagnostic message generation (type checker) addErrTc, addErrTcM, failWithTc, failWithTcM, checkTc, checkTcM, failIfTc, failIfTcM, mkErrInfo, addTcRnDiagnostic, addDetailedDiagnostic, mkTcRnMessage, reportDiagnostic, reportDiagnostics, warnIf, diagnosticTc, diagnosticTcM, addDiagnosticTc, addDiagnosticTcM, addDiagnostic, addDiagnosticAt, -- * Type constraints newTcEvBinds, newNoTcEvBinds, cloneEvBindsVar, addTcEvBind, addTopEvBinds, getTcEvTyCoVars, getTcEvBindsMap, setTcEvBindsMap, chooseUniqueOccTc, getConstraintVar, setConstraintVar, emitConstraints, emitStaticConstraints, emitSimple, emitSimples, emitImplication, emitImplications, emitInsoluble, emitDelayedErrors, emitHole, emitHoles, emitNotConcreteError, discardConstraints, captureConstraints, tryCaptureConstraints, pushLevelAndCaptureConstraints, pushTcLevelM_, pushTcLevelM, getTcLevel, setTcLevel, isTouchableTcM, getLclTypeEnv, setLclTypeEnv, traceTcConstraints, emitNamedTypeHole, IsExtraConstraint(..), emitAnonTypeHole, -- * Template Haskell context recordThUse, recordThSpliceUse, recordThNeededRuntimeDeps, keepAlive, getStage, getStageAndBindLevel, setStage, addModFinalizersWithLclEnv, -- * Safe Haskell context recordUnsafeInfer, finalSafeMode, fixSafeInstances, -- * Stuff for the renamer's local env getLocalRdrEnv, setLocalRdrEnv, -- * Stuff for interface decls mkIfLclEnv, initIfaceTcRn, initIfaceCheck, initIfaceLcl, initIfaceLclWithSubst, initIfaceLoad, initIfaceLoadModule, getIfModule, failIfM, forkM, setImplicitEnvM, withException, -- * Stuff for cost centres. getCCIndexM, getCCIndexTcM, -- * Types etc. module GHC.Tc.Types, module GHC.Data.IOEnv ) where import GHC.Prelude import GHC.Builtin.Names import GHC.Tc.Types -- Re-export all import GHC.Tc.Types.Constraint import GHC.Tc.Types.Evidence import GHC.Tc.Types.Origin import GHC.Tc.Utils.TcType import GHC.Hs hiding (LIE) import GHC.Unit import GHC.Unit.Env import GHC.Unit.External import GHC.Unit.Module.Warnings import GHC.Unit.Home.ModInfo import GHC.Core.UsageEnv import GHC.Core.Multiplicity import GHC.Core.InstEnv import GHC.Core.FamInstEnv import GHC.Driver.Env import GHC.Driver.Session import GHC.Driver.Config.Diagnostic import GHC.Runtime.Context import GHC.Data.IOEnv -- Re-export all import GHC.Data.Bag import GHC.Data.FastString import GHC.Data.Maybe import GHC.Utils.Outputable as Outputable import GHC.Utils.Error import GHC.Utils.Panic import GHC.Utils.Constants (debugIsOn) import GHC.Utils.Logger import qualified GHC.Data.Strict as Strict import GHC.Types.Error import GHC.Types.Fixity.Env import GHC.Types.Name.Reader import GHC.Types.Name import GHC.Types.SafeHaskell import GHC.Types.Id import GHC.Types.TypeEnv import GHC.Types.Var.Set import GHC.Types.Var.Env import GHC.Types.SrcLoc import GHC.Types.Name.Env import GHC.Types.Name.Set import GHC.Types.Name.Ppr import GHC.Types.Unique.FM ( emptyUFM ) import GHC.Types.Unique.Supply import GHC.Types.Annotations import GHC.Types.Basic( TopLevelFlag, TypeOrKind(..) ) import GHC.Types.CostCentre.State import GHC.Types.SourceFile import qualified GHC.LanguageExtensions as LangExt import Data.IORef import Control.Monad import GHC.Tc.Errors.Types import {-# SOURCE #-} GHC.Tc.Utils.Env ( tcInitTidyEnv ) import qualified Data.Map as Map import GHC.Driver.Env.KnotVars import GHC.Linker.Types import GHC.Types.Unique.DFM {- ************************************************************************ * * initTc * * ************************************************************************ -} -- | Setup the initial typechecking environment initTc :: HscEnv -> HscSource -> Bool -- True <=> retain renamed syntax trees -> Module -> RealSrcSpan -> TcM r -> IO (Messages TcRnMessage, Maybe r) -- Nothing => error thrown by the thing inside -- (error messages should have been printed already) initTc hsc_env hsc_src keep_rn_syntax mod loc do_this = do { keep_var <- newIORef emptyNameSet ; used_gre_var <- newIORef [] ; th_var <- newIORef False ; th_splice_var<- newIORef False ; infer_var <- newIORef True ; infer_reasons_var <- newIORef emptyMessages ; dfun_n_var <- newIORef emptyOccSet ; let { type_env_var = hsc_type_env_vars hsc_env }; dependent_files_var <- newIORef [] ; static_wc_var <- newIORef emptyWC ; cc_st_var <- newIORef newCostCentreState ; th_topdecls_var <- newIORef [] ; th_foreign_files_var <- newIORef [] ; th_topnames_var <- newIORef emptyNameSet ; th_modfinalizers_var <- newIORef [] ; th_coreplugins_var <- newIORef [] ; th_state_var <- newIORef Map.empty ; th_remote_state_var <- newIORef Nothing ; th_docs_var <- newIORef Map.empty ; th_needed_deps_var <- newIORef ([], emptyUDFM) ; next_wrapper_num <- newIORef emptyModuleEnv ; let { -- bangs to avoid leaking the env (#19356) !dflags = hsc_dflags hsc_env ; !mhome_unit = hsc_home_unit_maybe hsc_env; !logger = hsc_logger hsc_env ; maybe_rn_syntax :: forall a. a -> Maybe a ; maybe_rn_syntax empty_val | logHasDumpFlag logger Opt_D_dump_rn_ast = Just empty_val | gopt Opt_WriteHie dflags = Just empty_val -- We want to serialize the documentation in the .hi-files, -- and need to extract it from the renamed syntax first. -- See 'GHC.HsToCore.Docs.extractDocs'. | gopt Opt_Haddock dflags = Just empty_val | keep_rn_syntax = Just empty_val | otherwise = Nothing ; gbl_env = TcGblEnv { tcg_th_topdecls = th_topdecls_var, tcg_th_foreign_files = th_foreign_files_var, tcg_th_topnames = th_topnames_var, tcg_th_modfinalizers = th_modfinalizers_var, tcg_th_coreplugins = th_coreplugins_var, tcg_th_state = th_state_var, tcg_th_remote_state = th_remote_state_var, tcg_th_docs = th_docs_var, tcg_mod = mod, tcg_semantic_mod = homeModuleInstantiation mhome_unit mod, tcg_src = hsc_src, tcg_rdr_env = emptyGlobalRdrEnv, tcg_fix_env = emptyNameEnv, tcg_field_env = emptyNameEnv, tcg_default = if moduleUnit mod == primUnit || moduleUnit mod == bignumUnit then Just [] -- See Note [Default types] else Nothing, tcg_type_env = emptyNameEnv, tcg_type_env_var = type_env_var, tcg_inst_env = emptyInstEnv, tcg_fam_inst_env = emptyFamInstEnv, tcg_ann_env = emptyAnnEnv, tcg_th_used = th_var, tcg_th_splice_used = th_splice_var, tcg_th_needed_deps = th_needed_deps_var, tcg_exports = [], tcg_imports = emptyImportAvails, tcg_used_gres = used_gre_var, tcg_dus = emptyDUs, tcg_rn_imports = [], tcg_rn_exports = if hsc_src == HsigFile -- Always retain renamed syntax, so that we can give -- better errors. (TODO: how?) then Just [] else maybe_rn_syntax [], tcg_rn_decls = maybe_rn_syntax emptyRnGroup, tcg_tr_module = Nothing, tcg_binds = emptyLHsBinds, tcg_imp_specs = [], tcg_sigs = emptyNameSet, tcg_ksigs = emptyNameSet, tcg_ev_binds = emptyBag, tcg_warns = NoWarnings, tcg_anns = [], tcg_tcs = [], tcg_insts = [], tcg_fam_insts = [], tcg_rules = [], tcg_fords = [], tcg_patsyns = [], tcg_merged = [], tcg_dfun_n = dfun_n_var, tcg_keep = keep_var, tcg_doc_hdr = Nothing, tcg_hpc = False, tcg_main = Nothing, tcg_self_boot = NoSelfBoot, tcg_safe_infer = infer_var, tcg_safe_infer_reasons = infer_reasons_var, tcg_dependent_files = dependent_files_var, tcg_tc_plugin_solvers = [], tcg_tc_plugin_rewriters = emptyUFM, tcg_defaulting_plugins = [], tcg_hf_plugins = [], tcg_top_loc = loc, tcg_static_wc = static_wc_var, tcg_complete_matches = [], tcg_cc_st = cc_st_var, tcg_next_wrapper_num = next_wrapper_num } ; } ; -- OK, here's the business end! initTcWithGbl hsc_env gbl_env loc do_this } -- | Run a 'TcM' action in the context of an existing 'GblEnv'. initTcWithGbl :: HscEnv -> TcGblEnv -> RealSrcSpan -> TcM r -> IO (Messages TcRnMessage, Maybe r) initTcWithGbl hsc_env gbl_env loc do_this = do { lie_var <- newIORef emptyWC ; errs_var <- newIORef emptyMessages ; usage_var <- newIORef zeroUE ; let lcl_env = TcLclEnv { tcl_errs = errs_var, tcl_loc = loc, -- tcl_loc should be over-ridden very soon! tcl_in_gen_code = False, tcl_ctxt = [], tcl_rdr = emptyLocalRdrEnv, tcl_th_ctxt = topStage, tcl_th_bndrs = emptyNameEnv, tcl_arrow_ctxt = NoArrowCtxt, tcl_env = emptyNameEnv, tcl_usage = usage_var, tcl_bndrs = [], tcl_lie = lie_var, tcl_tclvl = topTcLevel } ; maybe_res <- initTcRnIf 'a' hsc_env gbl_env lcl_env $ do { r <- tryM do_this ; case r of Right res -> return (Just res) Left _ -> return Nothing } -- Check for unsolved constraints -- If we succeed (maybe_res = Just r), there should be -- no unsolved constraints. But if we exit via an -- exception (maybe_res = Nothing), we may have skipped -- solving, so don't panic then (#13466) ; lie <- readIORef (tcl_lie lcl_env) ; when (isJust maybe_res && not (isEmptyWC lie)) $ pprPanic "initTc: unsolved constraints" (ppr lie) -- Collect any error messages ; msgs <- readIORef (tcl_errs lcl_env) ; let { final_res | errorsFound msgs = Nothing | otherwise = maybe_res } ; return (msgs, final_res) } initTcInteractive :: HscEnv -> TcM a -> IO (Messages TcRnMessage, Maybe a) -- Initialise the type checker monad for use in GHCi initTcInteractive hsc_env thing_inside = initTc hsc_env HsSrcFile False (icInteractiveModule (hsc_IC hsc_env)) (realSrcLocSpan interactive_src_loc) thing_inside where interactive_src_loc = mkRealSrcLoc (fsLit "") 1 1 {- Note [Default types] ~~~~~~~~~~~~~~~~~~~~~~~ The Integer type is simply not available in ghc-prim and ghc-bignum packages (it is declared in ghc-bignum). So we set the defaulting types to (Just []), meaning there are no default types, rather than Nothing, which means "use the default default types of Integer, Double". If you don't do this, attempted defaulting in package ghc-prim causes an actual crash (attempting to look up the Integer type). ************************************************************************ * * Initialisation * * ************************************************************************ -} initTcRnIf :: Char -- ^ Mask for unique supply -> HscEnv -> gbl -> lcl -> TcRnIf gbl lcl a -> IO a initTcRnIf uniq_mask hsc_env gbl_env lcl_env thing_inside = do { let { env = Env { env_top = hsc_env, env_um = uniq_mask, env_gbl = gbl_env, env_lcl = lcl_env} } ; runIOEnv env thing_inside } {- ************************************************************************ * * Simple accessors * * ************************************************************************ -} discardResult :: TcM a -> TcM () discardResult a = a >> return () getTopEnv :: TcRnIf gbl lcl HscEnv getTopEnv = do { env <- getEnv; return (env_top env) } updTopEnv :: (HscEnv -> HscEnv) -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a updTopEnv upd = updEnv (\ env@(Env { env_top = top }) -> env { env_top = upd top }) getGblEnv :: TcRnIf gbl lcl gbl getGblEnv = do { Env{..} <- getEnv; return env_gbl } updGblEnv :: (gbl -> gbl) -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a updGblEnv upd = updEnv (\ env@(Env { env_gbl = gbl }) -> env { env_gbl = upd gbl }) setGblEnv :: gbl' -> TcRnIf gbl' lcl a -> TcRnIf gbl lcl a setGblEnv gbl_env = updEnv (\ env -> env { env_gbl = gbl_env }) getLclEnv :: TcRnIf gbl lcl lcl getLclEnv = do { Env{..} <- getEnv; return env_lcl } updLclEnv :: (lcl -> lcl) -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a updLclEnv upd = updEnv (\ env@(Env { env_lcl = lcl }) -> env { env_lcl = upd lcl }) setLclEnv :: lcl' -> TcRnIf gbl lcl' a -> TcRnIf gbl lcl a setLclEnv lcl_env = updEnv (\ env -> env { env_lcl = lcl_env }) restoreLclEnv :: TcLclEnv -> TcRnIf gbl TcLclEnv a -> TcRnIf gbl TcLclEnv a -- See Note [restoreLclEnv vs setLclEnv] restoreLclEnv new_lcl_env = updLclEnv upd where upd old_lcl_env = new_lcl_env { tcl_errs = tcl_errs old_lcl_env , tcl_lie = tcl_lie old_lcl_env , tcl_usage = tcl_usage old_lcl_env } getEnvs :: TcRnIf gbl lcl (gbl, lcl) getEnvs = do { env <- getEnv; return (env_gbl env, env_lcl env) } setEnvs :: (gbl', lcl') -> TcRnIf gbl' lcl' a -> TcRnIf gbl lcl a setEnvs (gbl_env, lcl_env) = setGblEnv gbl_env . setLclEnv lcl_env updEnvs :: ((gbl,lcl) -> (gbl, lcl)) -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a updEnvs upd_envs = updEnv upd where upd env@(Env { env_gbl = gbl, env_lcl = lcl }) = env { env_gbl = gbl', env_lcl = lcl' } where !(gbl', lcl') = upd_envs (gbl, lcl) restoreEnvs :: (TcGblEnv, TcLclEnv) -> TcRn a -> TcRn a -- See Note [restoreLclEnv vs setLclEnv] restoreEnvs (gbl, lcl) = setGblEnv gbl . restoreLclEnv lcl {- Note [restoreLclEnv vs setLclEnv] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In the typechecker we use this idiom quite a lot do { (gbl_env, lcl_env) <- tcRnSrcDecls ... ; setGblEnv gbl_env $ setLclEnv lcl_env $ more_stuff } The `tcRnSrcDecls` extends the environments in `gbl_env` and `lcl_env` which we then want to be in scope in `more stuff`. The problem is that `lcl_env :: TcLclEnv` has an IORef for error messages `tcl_errs`, and another for constraints (`tcl_lie`), and another for Linear Haskell usage information (`tcl_usage`). Now suppose we change it a tiny bit do { (gbl_env, lcl_env) <- checkNoErrs $ tcRnSrcDecls ... ; setGblEnv gbl_env $ setLclEnv lcl_env $ more_stuff } That should be innocuous. But *alas*, `checkNoErrs` gathers errors in a fresh IORef *which is then captured in the returned `lcl_env`. When we do the `setLclEnv` we'll make that captured IORef into the place where we gather error messages -- but no one is going to look at that!!! This led to #19470 and #20981. Solution: instead of setLclEnv use restoreLclEnv, which preserves from the /parent/ context these mutable collection IORefs: tcl_errs, tcl_lie, tcl_usage -} -- Command-line flags xoptM :: LangExt.Extension -> TcRnIf gbl lcl Bool xoptM flag = xopt flag <$> getDynFlags doptM :: DumpFlag -> TcRnIf gbl lcl Bool doptM flag = do logger <- getLogger return (logHasDumpFlag logger flag) goptM :: GeneralFlag -> TcRnIf gbl lcl Bool goptM flag = gopt flag <$> getDynFlags woptM :: WarningFlag -> TcRnIf gbl lcl Bool woptM flag = wopt flag <$> getDynFlags setXOptM :: LangExt.Extension -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a setXOptM flag = updTopFlags (\dflags -> xopt_set dflags flag) unsetXOptM :: LangExt.Extension -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a unsetXOptM flag = updTopFlags (\dflags -> xopt_unset dflags flag) unsetGOptM :: GeneralFlag -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a unsetGOptM flag = updTopFlags (\dflags -> gopt_unset dflags flag) unsetWOptM :: WarningFlag -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a unsetWOptM flag = updTopFlags (\dflags -> wopt_unset dflags flag) -- | Do it flag is true whenDOptM :: DumpFlag -> TcRnIf gbl lcl () -> TcRnIf gbl lcl () whenDOptM flag thing_inside = do b <- doptM flag when b thing_inside {-# INLINE whenDOptM #-} -- see Note [INLINE conditional tracing utilities] whenGOptM :: GeneralFlag -> TcRnIf gbl lcl () -> TcRnIf gbl lcl () whenGOptM flag thing_inside = do b <- goptM flag when b thing_inside {-# INLINE whenGOptM #-} -- see Note [INLINE conditional tracing utilities] whenWOptM :: WarningFlag -> TcRnIf gbl lcl () -> TcRnIf gbl lcl () whenWOptM flag thing_inside = do b <- woptM flag when b thing_inside {-# INLINE whenWOptM #-} -- see Note [INLINE conditional tracing utilities] whenXOptM :: LangExt.Extension -> TcRnIf gbl lcl () -> TcRnIf gbl lcl () whenXOptM flag thing_inside = do b <- xoptM flag when b thing_inside {-# INLINE whenXOptM #-} -- see Note [INLINE conditional tracing utilities] unlessXOptM :: LangExt.Extension -> TcRnIf gbl lcl () -> TcRnIf gbl lcl () unlessXOptM flag thing_inside = do b <- xoptM flag unless b thing_inside {-# INLINE unlessXOptM #-} -- see Note [INLINE conditional tracing utilities] getGhcMode :: TcRnIf gbl lcl GhcMode getGhcMode = ghcMode <$> getDynFlags withoutDynamicNow :: TcRnIf gbl lcl a -> TcRnIf gbl lcl a withoutDynamicNow = updTopFlags (\dflags -> dflags { dynamicNow = False}) updTopFlags :: (DynFlags -> DynFlags) -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a updTopFlags f = updTopEnv (hscUpdateFlags f) getEpsVar :: TcRnIf gbl lcl (TcRef ExternalPackageState) getEpsVar = do env <- getTopEnv return (euc_eps (ue_eps (hsc_unit_env env))) getEps :: TcRnIf gbl lcl ExternalPackageState getEps = do { env <- getTopEnv; liftIO $ hscEPS env } -- | Update the external package state. Returns the second result of the -- modifier function. -- -- This is an atomic operation and forces evaluation of the modified EPS in -- order to avoid space leaks. updateEps :: (ExternalPackageState -> (ExternalPackageState, a)) -> TcRnIf gbl lcl a updateEps upd_fn = do traceIf (text "updating EPS") eps_var <- getEpsVar atomicUpdMutVar' eps_var upd_fn -- | Update the external package state. -- -- This is an atomic operation and forces evaluation of the modified EPS in -- order to avoid space leaks. updateEps_ :: (ExternalPackageState -> ExternalPackageState) -> TcRnIf gbl lcl () updateEps_ upd_fn = updateEps (\eps -> (upd_fn eps, ())) getHpt :: TcRnIf gbl lcl HomePackageTable getHpt = do { env <- getTopEnv; return (hsc_HPT env) } getEpsAndHug :: TcRnIf gbl lcl (ExternalPackageState, HomeUnitGraph) getEpsAndHug = do { env <- getTopEnv; eps <- liftIO $ hscEPS env ; return (eps, hsc_HUG env) } -- | A convenient wrapper for taking a @MaybeErr SDoc a@ and throwing -- an exception if it is an error. withException :: MonadIO m => SDocContext -> m (MaybeErr SDoc a) -> m a withException ctx do_this = do r <- do_this case r of Failed err -> liftIO $ throwGhcExceptionIO (ProgramError (renderWithContext ctx err)) Succeeded result -> return result {- ************************************************************************ * * Arrow scopes * * ************************************************************************ -} newArrowScope :: TcM a -> TcM a newArrowScope = updLclEnv $ \env -> env { tcl_arrow_ctxt = ArrowCtxt (tcl_rdr env) (tcl_lie env) } -- Return to the stored environment (from the enclosing proc) escapeArrowScope :: TcM a -> TcM a escapeArrowScope = updLclEnv $ \ env -> case tcl_arrow_ctxt env of NoArrowCtxt -> env ArrowCtxt rdr_env lie -> env { tcl_arrow_ctxt = NoArrowCtxt , tcl_lie = lie , tcl_rdr = rdr_env } {- ************************************************************************ * * Unique supply * * ************************************************************************ -} newUnique :: TcRnIf gbl lcl Unique newUnique = do { env <- getEnv ; let mask = env_um env ; liftIO $! uniqFromMask mask } newUniqueSupply :: TcRnIf gbl lcl UniqSupply newUniqueSupply = do { env <- getEnv ; let mask = env_um env ; liftIO $! mkSplitUniqSupply mask } cloneLocalName :: Name -> TcM Name -- Make a fresh Internal name with the same OccName and SrcSpan cloneLocalName name = newNameAt (nameOccName name) (nameSrcSpan name) newName :: OccName -> TcM Name newName occ = do { loc <- getSrcSpanM ; newNameAt occ loc } newNameAt :: OccName -> SrcSpan -> TcM Name newNameAt occ span = do { uniq <- newUnique ; return (mkInternalName uniq occ span) } newSysName :: OccName -> TcRnIf gbl lcl Name newSysName occ = do { uniq <- newUnique ; return (mkSystemName uniq occ) } newSysLocalId :: FastString -> Mult -> TcType -> TcRnIf gbl lcl TcId newSysLocalId fs w ty = do { u <- newUnique ; return (mkSysLocal fs u w ty) } newSysLocalIds :: FastString -> [Scaled TcType] -> TcRnIf gbl lcl [TcId] newSysLocalIds fs tys = do { us <- newUniqueSupply ; let mkId' n (Scaled w t) = mkSysLocal fs n w t ; return (zipWith mkId' (uniqsFromSupply us) tys) } instance MonadUnique (IOEnv (Env gbl lcl)) where getUniqueM = newUnique getUniqueSupplyM = newUniqueSupply {- ************************************************************************ * * Accessing input/output * * ************************************************************************ -} newTcRef :: a -> TcRnIf gbl lcl (TcRef a) newTcRef = newMutVar readTcRef :: TcRef a -> TcRnIf gbl lcl a readTcRef = readMutVar writeTcRef :: TcRef a -> a -> TcRnIf gbl lcl () writeTcRef = writeMutVar updTcRef :: TcRef a -> (a -> a) -> TcRnIf gbl lcl () -- Returns () updTcRef ref fn = liftIO $ modifyIORef' ref fn {- ************************************************************************ * * Debugging * * ************************************************************************ -} {- Note [INLINE conditional tracing utilities] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In general we want to optimise for the case where tracing is not enabled. To ensure this happens, we ensure that traceTc and friends are inlined; this ensures that the allocation of the document can be pushed into the tracing path, keeping the non-traced path free of this extraneous work. For instance, if we don't inline traceTc, we'll get let stuff_to_print = ... in traceTc "wombat" stuff_to_print and the stuff_to_print thunk will be allocated in the "hot path", regardless of tracing. But if we INLINE traceTc we get let stuff_to_print = ... in if doTracing then emitTraceMsg "wombat" stuff_to_print else return () and then we float in: if doTracing then let stuff_to_print = ... in emitTraceMsg "wombat" stuff_to_print else return () Now stuff_to_print is allocated only in the "cold path". Moreover, on the "cold" path, after the conditional, we want to inline as /little/ as possible. Performance doesn't matter here, and we'd like to bloat the caller's code as little as possible. So we put a NOINLINE on 'emitTraceMsg' See #18168. -} -- Typechecker trace traceTc :: String -> SDoc -> TcRn () traceTc herald doc = labelledTraceOptTcRn Opt_D_dump_tc_trace herald doc {-# INLINE traceTc #-} -- see Note [INLINE conditional tracing utilities] -- Renamer Trace traceRn :: String -> SDoc -> TcRn () traceRn herald doc = labelledTraceOptTcRn Opt_D_dump_rn_trace herald doc {-# INLINE traceRn #-} -- see Note [INLINE conditional tracing utilities] -- | Trace when a certain flag is enabled. This is like `traceOptTcRn` -- but accepts a string as a label and formats the trace message uniformly. labelledTraceOptTcRn :: DumpFlag -> String -> SDoc -> TcRn () labelledTraceOptTcRn flag herald doc = traceOptTcRn flag (formatTraceMsg herald doc) {-# INLINE labelledTraceOptTcRn #-} -- see Note [INLINE conditional tracing utilities] formatTraceMsg :: String -> SDoc -> SDoc formatTraceMsg herald doc = hang (text herald) 2 doc traceOptTcRn :: DumpFlag -> SDoc -> TcRn () traceOptTcRn flag doc = whenDOptM flag $ dumpTcRn False flag "" FormatText doc {-# INLINE traceOptTcRn #-} -- see Note [INLINE conditional tracing utilities] -- | Dump if the given 'DumpFlag' is set. dumpOptTcRn :: DumpFlag -> String -> DumpFormat -> SDoc -> TcRn () dumpOptTcRn flag title fmt doc = whenDOptM flag $ dumpTcRn False flag title fmt doc {-# INLINE dumpOptTcRn #-} -- see Note [INLINE conditional tracing utilities] -- | Unconditionally dump some trace output -- -- Certain tests (T3017, Roles3, T12763 etc.) expect part of the -- output generated by `-ddump-types` to be in 'PprUser' style. However, -- generally we want all other debugging output to use 'PprDump' -- style. We 'PprUser' style if 'useUserStyle' is True. -- dumpTcRn :: Bool -> DumpFlag -> String -> DumpFormat -> SDoc -> TcRn () dumpTcRn useUserStyle flag title fmt doc = do logger <- getLogger printer <- getPrintUnqualified real_doc <- wrapDocLoc doc let sty = if useUserStyle then mkUserStyle printer AllTheWay else mkDumpStyle printer liftIO $ logDumpFile logger sty flag title fmt real_doc -- | Add current location if -dppr-debug -- (otherwise the full location is usually way too much) wrapDocLoc :: SDoc -> TcRn SDoc wrapDocLoc doc = do logger <- getLogger if logHasDumpFlag logger Opt_D_ppr_debug then do loc <- getSrcSpanM return (mkLocMessage MCOutput loc doc) else return doc getPrintUnqualified :: TcRn PrintUnqualified getPrintUnqualified = do { rdr_env <- getGlobalRdrEnv ; hsc_env <- getTopEnv ; return $ mkPrintUnqualified (hsc_unit_env hsc_env) rdr_env } -- | Like logInfoTcRn, but for user consumption printForUserTcRn :: SDoc -> TcRn () printForUserTcRn doc = do logger <- getLogger printer <- getPrintUnqualified liftIO (printOutputForUser logger printer doc) {- traceIf works in the TcRnIf monad, where no RdrEnv is available. Alas, they behave inconsistently with the other stuff; e.g. are unaffected by -dump-to-file. -} traceIf :: SDoc -> TcRnIf m n () traceIf = traceOptIf Opt_D_dump_if_trace {-# INLINE traceIf #-} -- see Note [INLINE conditional tracing utilities] traceOptIf :: DumpFlag -> SDoc -> TcRnIf m n () traceOptIf flag doc = whenDOptM flag $ do -- No RdrEnv available, so qualify everything logger <- getLogger liftIO (putMsg logger doc) {-# INLINE traceOptIf #-} -- see Note [INLINE conditional tracing utilities] {- ************************************************************************ * * Typechecker global environment * * ************************************************************************ -} getIsGHCi :: TcRn Bool getIsGHCi = do { mod <- getModule ; return (isInteractiveModule mod) } getGHCiMonad :: TcRn Name getGHCiMonad = do { hsc <- getTopEnv; return (ic_monad $ hsc_IC hsc) } getInteractivePrintName :: TcRn Name getInteractivePrintName = do { hsc <- getTopEnv; return (ic_int_print $ hsc_IC hsc) } tcIsHsBootOrSig :: TcRn Bool tcIsHsBootOrSig = do { env <- getGblEnv; return (isHsBootOrSig (tcg_src env)) } tcIsHsig :: TcRn Bool tcIsHsig = do { env <- getGblEnv; return (isHsigFile (tcg_src env)) } tcSelfBootInfo :: TcRn SelfBootInfo tcSelfBootInfo = do { env <- getGblEnv; return (tcg_self_boot env) } getGlobalRdrEnv :: TcRn GlobalRdrEnv getGlobalRdrEnv = do { env <- getGblEnv; return (tcg_rdr_env env) } getRdrEnvs :: TcRn (GlobalRdrEnv, LocalRdrEnv) getRdrEnvs = do { (gbl,lcl) <- getEnvs; return (tcg_rdr_env gbl, tcl_rdr lcl) } getImports :: TcRn ImportAvails getImports = do { env <- getGblEnv; return (tcg_imports env) } getFixityEnv :: TcRn FixityEnv getFixityEnv = do { env <- getGblEnv; return (tcg_fix_env env) } extendFixityEnv :: [(Name,FixItem)] -> RnM a -> RnM a extendFixityEnv new_bit = updGblEnv (\env@(TcGblEnv { tcg_fix_env = old_fix_env }) -> env {tcg_fix_env = extendNameEnvList old_fix_env new_bit}) getRecFieldEnv :: TcRn RecFieldEnv getRecFieldEnv = do { env <- getGblEnv; return (tcg_field_env env) } getDeclaredDefaultTys :: TcRn (Maybe [Type]) getDeclaredDefaultTys = do { env <- getGblEnv; return (tcg_default env) } addDependentFiles :: [FilePath] -> TcRn () addDependentFiles fs = do ref <- fmap tcg_dependent_files getGblEnv dep_files <- readTcRef ref writeTcRef ref (fs ++ dep_files) {- ************************************************************************ * * Error management * * ************************************************************************ -} getSrcSpanM :: TcRn SrcSpan -- Avoid clash with Name.getSrcLoc getSrcSpanM = do { env <- getLclEnv; return (RealSrcSpan (tcl_loc env) Strict.Nothing) } -- See Note [Error contexts in generated code] inGeneratedCode :: TcRn Bool inGeneratedCode = tcl_in_gen_code <$> getLclEnv setSrcSpan :: SrcSpan -> TcRn a -> TcRn a -- See Note [Error contexts in generated code] -- for the tcl_in_gen_code manipulation setSrcSpan (RealSrcSpan loc _) thing_inside = updLclEnv (\env -> env { tcl_loc = loc, tcl_in_gen_code = False }) thing_inside setSrcSpan loc@(UnhelpfulSpan _) thing_inside | isGeneratedSrcSpan loc = updLclEnv (\env -> env { tcl_in_gen_code = True }) thing_inside | otherwise = thing_inside setSrcSpanA :: SrcSpanAnn' ann -> TcRn a -> TcRn a setSrcSpanA l = setSrcSpan (locA l) addLocM :: (a -> TcM b) -> Located a -> TcM b addLocM fn (L loc a) = setSrcSpan loc $ fn a addLocMA :: (a -> TcM b) -> GenLocated (SrcSpanAnn' ann) a -> TcM b addLocMA fn (L loc a) = setSrcSpanA loc $ fn a wrapLocM :: (a -> TcM b) -> Located a -> TcM (Located b) wrapLocM fn (L loc a) = setSrcSpan loc $ do { b <- fn a ; return (L loc b) } wrapLocAM :: (a -> TcM b) -> LocatedAn an a -> TcM (Located b) wrapLocAM fn a = wrapLocM fn (reLoc a) wrapLocMA :: (a -> TcM b) -> GenLocated (SrcSpanAnn' ann) a -> TcRn (GenLocated (SrcSpanAnn' ann) b) wrapLocMA fn (L loc a) = setSrcSpanA loc $ do { b <- fn a ; return (L loc b) } wrapLocFstM :: (a -> TcM (b,c)) -> Located a -> TcM (Located b, c) wrapLocFstM fn (L loc a) = setSrcSpan loc $ do (b,c) <- fn a return (L loc b, c) -- Possible instantiations: -- wrapLocFstMA :: (a -> TcM (b,c)) -> LocatedA a -> TcM (LocatedA b, c) -- wrapLocFstMA :: (a -> TcM (b,c)) -> LocatedN a -> TcM (LocatedN b, c) -- wrapLocFstMA :: (a -> TcM (b,c)) -> LocatedAn t a -> TcM (LocatedAn t b, c) -- and so on. wrapLocFstMA :: (a -> TcM (b,c)) -> GenLocated (SrcSpanAnn' ann) a -> TcM (GenLocated (SrcSpanAnn' ann) b, c) wrapLocFstMA fn (L loc a) = setSrcSpanA loc $ do (b,c) <- fn a return (L loc b, c) wrapLocSndM :: (a -> TcM (b, c)) -> Located a -> TcM (b, Located c) wrapLocSndM fn (L loc a) = setSrcSpan loc $ do (b,c) <- fn a return (b, L loc c) -- Possible instantiations: -- wrapLocSndMA :: (a -> TcM (b, c)) -> LocatedA a -> TcM (b, LocatedA c) -- wrapLocSndMA :: (a -> TcM (b, c)) -> LocatedN a -> TcM (b, LocatedN c) -- wrapLocSndMA :: (a -> TcM (b, c)) -> LocatedAn t a -> TcM (b, LocatedAn t c) -- and so on. wrapLocSndMA :: (a -> TcM (b, c)) -> GenLocated (SrcSpanAnn' ann) a -> TcM (b, GenLocated (SrcSpanAnn' ann) c) wrapLocSndMA fn (L loc a) = setSrcSpanA loc $ do (b,c) <- fn a return (b, L loc c) wrapLocM_ :: (a -> TcM ()) -> Located a -> TcM () wrapLocM_ fn (L loc a) = setSrcSpan loc (fn a) wrapLocMA_ :: (a -> TcM ()) -> LocatedA a -> TcM () wrapLocMA_ fn (L loc a) = setSrcSpan (locA loc) (fn a) -- Reporting errors getErrsVar :: TcRn (TcRef (Messages TcRnMessage)) getErrsVar = do { env <- getLclEnv; return (tcl_errs env) } setErrsVar :: TcRef (Messages TcRnMessage) -> TcRn a -> TcRn a setErrsVar v = updLclEnv (\ env -> env { tcl_errs = v }) addErr :: TcRnMessage -> TcRn () addErr msg = do { loc <- getSrcSpanM; addErrAt loc msg } failWith :: TcRnMessage -> TcRn a failWith msg = addErr msg >> failM failAt :: SrcSpan -> TcRnMessage -> TcRn a failAt loc msg = addErrAt loc msg >> failM addErrAt :: SrcSpan -> TcRnMessage -> TcRn () -- addErrAt is mainly (exclusively?) used by the renamer, where -- tidying is not an issue, but it's all lazy so the extra -- work doesn't matter addErrAt loc msg = do { ctxt <- getErrCtxt ; tidy_env <- tcInitTidyEnv ; err_info <- mkErrInfo tidy_env ctxt ; add_long_err_at loc (TcRnMessageDetailed (ErrInfo err_info Outputable.empty) msg) } addErrs :: [(SrcSpan,TcRnMessage)] -> TcRn () addErrs msgs = mapM_ add msgs where add (loc,msg) = addErrAt loc msg checkErr :: Bool -> TcRnMessage -> TcRn () -- Add the error if the bool is False checkErr ok msg = unless ok (addErr msg) addMessages :: Messages TcRnMessage -> TcRn () addMessages msgs1 = do { errs_var <- getErrsVar ; msgs0 <- readTcRef errs_var ; writeTcRef errs_var (msgs0 `unionMessages` msgs1) } discardWarnings :: TcRn a -> TcRn a -- Ignore warnings inside the thing inside; -- used to ignore-unused-variable warnings inside derived code discardWarnings thing_inside = do { errs_var <- getErrsVar ; old_warns <- getWarningMessages <$> readTcRef errs_var ; result <- thing_inside -- Revert warnings to old_warns ; new_errs <- getErrorMessages <$> readTcRef errs_var ; writeTcRef errs_var $ mkMessages (old_warns `unionBags` new_errs) ; return result } {- ************************************************************************ * * Shared error message stuff: renamer and typechecker * * ************************************************************************ -} add_long_err_at :: SrcSpan -> TcRnMessageDetailed -> TcRn () add_long_err_at loc msg = mk_long_err_at loc msg >>= reportDiagnostic where mk_long_err_at :: SrcSpan -> TcRnMessageDetailed -> TcRn (MsgEnvelope TcRnMessage) mk_long_err_at loc msg = do { printer <- getPrintUnqualified ; unit_state <- hsc_units <$> getTopEnv ; return $ mkErrorMsgEnvelope loc printer $ TcRnMessageWithInfo unit_state msg } mkTcRnMessage :: SrcSpan -> TcRnMessage -> TcRn (MsgEnvelope TcRnMessage) mkTcRnMessage loc msg = do { printer <- getPrintUnqualified ; diag_opts <- initDiagOpts <$> getDynFlags ; return $ mkMsgEnvelope diag_opts loc printer msg } reportDiagnostics :: [MsgEnvelope TcRnMessage] -> TcM () reportDiagnostics = mapM_ reportDiagnostic reportDiagnostic :: MsgEnvelope TcRnMessage -> TcRn () reportDiagnostic msg = do { traceTc "Adding diagnostic:" (pprLocMsgEnvelope msg) ; errs_var <- getErrsVar ; msgs <- readTcRef errs_var ; writeTcRef errs_var (msg `addMessage` msgs) } ----------------------- checkNoErrs :: TcM r -> TcM r -- (checkNoErrs m) succeeds iff m succeeds and generates no errors -- If m fails then (checkNoErrs m) fails. -- If m succeeds, it checks whether m generated any errors messages -- (it might have recovered internally) -- If so, it fails too. -- Regardless, any errors generated by m are propagated to the enclosing context. checkNoErrs main = do { (res, no_errs) <- askNoErrs main ; unless no_errs failM ; return res } ----------------------- whenNoErrs :: TcM () -> TcM () whenNoErrs thing = ifErrsM (return ()) thing ifErrsM :: TcRn r -> TcRn r -> TcRn r -- ifErrsM bale_out normal -- does 'bale_out' if there are errors in errors collection -- otherwise does 'normal' ifErrsM bale_out normal = do { errs_var <- getErrsVar ; msgs <- readTcRef errs_var ; if errorsFound msgs then bale_out else normal } failIfErrsM :: TcRn () -- Useful to avoid error cascades failIfErrsM = ifErrsM failM (return ()) {- ********************************************************************* * * Context management for the type checker * * ************************************************************************ -} {- Note [Inlining addErrCtxt] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You will notice a bunch of INLINE pragamas on addErrCtxt and friends. The reason is to promote better eta-expansion in client modules. Consider \e s. addErrCtxt c (tc_foo x) e s It looks as if tc_foo is applied to only two arguments, but if we inline addErrCtxt it'll turn into something more like \e s. tc_foo x (munge c e) s This is much better because Called Arity analysis can see that tc_foo is applied to four arguments. See #18379 for a concrete example. This reliance on delicate inlining and Called Arity is not good. See #18202 for a more general approach. But meanwhile, these ininings seem unobjectional, and they solve the immediate problem. Note [Error contexts in generated code] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * setSrcSpan sets tc_in_gen_code to True if the SrcSpan is GeneratedSrcSpan, and back to False when we get a useful SrcSpan * When tc_in_gen_code is True, addErrCtxt becomes a no-op. So typically it's better to do setSrcSpan /before/ addErrCtxt. See Note [Rebindable syntax and HsExpansion] in GHC.Hs.Expr for more discussion of this fancy footwork. -} getErrCtxt :: TcM [ErrCtxt] getErrCtxt = do { env <- getLclEnv; return (tcl_ctxt env) } setErrCtxt :: [ErrCtxt] -> TcM a -> TcM a {-# INLINE setErrCtxt #-} -- Note [Inlining addErrCtxt] setErrCtxt ctxt = updLclEnv (\ env -> env { tcl_ctxt = ctxt }) -- | Add a fixed message to the error context. This message should not -- do any tidying. addErrCtxt :: SDoc -> TcM a -> TcM a {-# INLINE addErrCtxt #-} -- Note [Inlining addErrCtxt] addErrCtxt msg = addErrCtxtM (\env -> return (env, msg)) -- | Add a message to the error context. This message may do tidying. addErrCtxtM :: (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcM a -> TcM a {-# INLINE addErrCtxtM #-} -- Note [Inlining addErrCtxt] addErrCtxtM ctxt = pushCtxt (False, ctxt) -- | Add a fixed landmark message to the error context. A landmark -- message is always sure to be reported, even if there is a lot of -- context. It also doesn't count toward the maximum number of contexts -- reported. addLandmarkErrCtxt :: SDoc -> TcM a -> TcM a {-# INLINE addLandmarkErrCtxt #-} -- Note [Inlining addErrCtxt] addLandmarkErrCtxt msg = addLandmarkErrCtxtM (\env -> return (env, msg)) -- | Variant of 'addLandmarkErrCtxt' that allows for monadic operations -- and tidying. addLandmarkErrCtxtM :: (TidyEnv -> TcM (TidyEnv, SDoc)) -> TcM a -> TcM a {-# INLINE addLandmarkErrCtxtM #-} -- Note [Inlining addErrCtxt] addLandmarkErrCtxtM ctxt = pushCtxt (True, ctxt) pushCtxt :: ErrCtxt -> TcM a -> TcM a {-# INLINE pushCtxt #-} -- Note [Inlining addErrCtxt] pushCtxt ctxt = updLclEnv (updCtxt ctxt) updCtxt :: ErrCtxt -> TcLclEnv -> TcLclEnv -- Do not update the context if we are in generated code -- See Note [Rebindable syntax and HsExpansion] in GHC.Hs.Expr updCtxt ctxt env@(TcLclEnv { tcl_ctxt = ctxts, tcl_in_gen_code = in_gen }) | in_gen = env | otherwise = env { tcl_ctxt = ctxt : ctxts } popErrCtxt :: TcM a -> TcM a popErrCtxt = updLclEnv (\ env@(TcLclEnv { tcl_ctxt = ctxt }) -> env { tcl_ctxt = pop ctxt }) where pop [] = [] pop (_:msgs) = msgs getCtLocM :: CtOrigin -> Maybe TypeOrKind -> TcM CtLoc getCtLocM origin t_or_k = do { env <- getLclEnv ; return (CtLoc { ctl_origin = origin , ctl_env = env , ctl_t_or_k = t_or_k , ctl_depth = initialSubGoalDepth }) } setCtLocM :: CtLoc -> TcM a -> TcM a -- Set the SrcSpan and error context from the CtLoc setCtLocM (CtLoc { ctl_env = lcl }) thing_inside = updLclEnv (\env -> env { tcl_loc = tcl_loc lcl , tcl_bndrs = tcl_bndrs lcl , tcl_ctxt = tcl_ctxt lcl }) thing_inside {- ********************************************************************* * * Error recovery and exceptions * * ********************************************************************* -} tcTryM :: TcRn r -> TcRn (Maybe r) -- The most basic function: catch the exception -- Nothing => an exception happened -- Just r => no exception, result R -- Errors and constraints are propagated in both cases -- Never throws an exception tcTryM thing_inside = do { either_res <- tryM thing_inside ; return (case either_res of Left _ -> Nothing Right r -> Just r) } -- In the Left case the exception is always the IOEnv -- built-in in exception; see IOEnv.failM ----------------------- capture_constraints :: TcM r -> TcM (r, WantedConstraints) -- capture_constraints simply captures and returns the -- constraints generated by thing_inside -- Precondition: thing_inside must not throw an exception! -- Reason for precondition: an exception would blow past the place -- where we read the lie_var, and we'd lose the constraints altogether capture_constraints thing_inside = do { lie_var <- newTcRef emptyWC ; res <- updLclEnv (\ env -> env { tcl_lie = lie_var }) $ thing_inside ; lie <- readTcRef lie_var ; return (res, lie) } capture_messages :: TcM r -> TcM (r, Messages TcRnMessage) -- capture_messages simply captures and returns the -- errors arnd warnings generated by thing_inside -- Precondition: thing_inside must not throw an exception! -- Reason for precondition: an exception would blow past the place -- where we read the msg_var, and we'd lose the constraints altogether capture_messages thing_inside = do { msg_var <- newTcRef emptyMessages ; res <- setErrsVar msg_var thing_inside ; msgs <- readTcRef msg_var ; return (res, msgs) } ----------------------- -- (askNoErrs m) runs m -- If m fails, -- then (askNoErrs m) fails, propagating only -- insoluble constraints -- -- If m succeeds with result r, -- then (askNoErrs m) succeeds with result (r, b), -- where b is True iff m generated no errors -- -- Regardless of success or failure, -- propagate any errors/warnings generated by m askNoErrs :: TcRn a -> TcRn (a, Bool) askNoErrs thing_inside = do { ((mb_res, lie), msgs) <- capture_messages $ capture_constraints $ tcTryM thing_inside ; addMessages msgs ; case mb_res of Nothing -> do { emitConstraints (dropMisleading lie) ; failM } Just res -> do { emitConstraints lie ; let errs_found = errorsFound msgs || insolubleWC lie ; return (res, not errs_found) } } ----------------------- tryCaptureConstraints :: TcM a -> TcM (Maybe a, WantedConstraints) -- (tryCaptureConstraints_maybe m) runs m, -- and returns the type constraints it generates -- It never throws an exception; instead if thing_inside fails, -- it returns Nothing and the /insoluble/ constraints -- Error messages are propagated tryCaptureConstraints thing_inside = do { (mb_res, lie) <- capture_constraints $ tcTryM thing_inside -- See Note [Constraints and errors] ; let lie_to_keep = case mb_res of Nothing -> dropMisleading lie Just {} -> lie ; return (mb_res, lie_to_keep) } captureConstraints :: TcM a -> TcM (a, WantedConstraints) -- (captureConstraints m) runs m, and returns the type constraints it generates -- If thing_inside fails (throwing an exception), -- then (captureConstraints thing_inside) fails too -- propagating the insoluble constraints only -- Error messages are propagated in either case captureConstraints thing_inside = do { (mb_res, lie) <- tryCaptureConstraints thing_inside -- See Note [Constraints and errors] -- If the thing_inside threw an exception, emit the insoluble -- constraints only (returned by tryCaptureConstraints) -- so that they are not lost ; case mb_res of Nothing -> do { emitConstraints lie; failM } Just res -> return (res, lie) } ----------------------- -- | @tcCollectingUsage thing_inside@ runs @thing_inside@ and returns the usage -- information which was collected as part of the execution of -- @thing_inside@. Careful: @tcCollectingUsage thing_inside@ itself does not -- report any usage information, it's up to the caller to incorporate the -- returned usage information into the larger context appropriately. tcCollectingUsage :: TcM a -> TcM (UsageEnv,a) tcCollectingUsage thing_inside = do { local_usage_ref <- newTcRef zeroUE ; result <- updLclEnv (\env -> env { tcl_usage = local_usage_ref }) thing_inside ; local_usage <- readTcRef local_usage_ref ; return (local_usage,result) } -- | @tcScalingUsage mult thing_inside@ runs @thing_inside@ and scales all the -- usage information by @mult@. tcScalingUsage :: Mult -> TcM a -> TcM a tcScalingUsage mult thing_inside = do { (usage, result) <- tcCollectingUsage thing_inside ; traceTc "tcScalingUsage" (ppr mult) ; tcEmitBindingUsage $ scaleUE mult usage ; return result } tcEmitBindingUsage :: UsageEnv -> TcM () tcEmitBindingUsage ue = do { lcl_env <- getLclEnv ; let usage = tcl_usage lcl_env ; updTcRef usage (addUE ue) } ----------------------- attemptM :: TcRn r -> TcRn (Maybe r) -- (attemptM thing_inside) runs thing_inside -- If thing_inside succeeds, returning r, -- we return (Just r), and propagate all constraints and errors -- If thing_inside fail, throwing an exception, -- we return Nothing, propagating insoluble constraints, -- and all errors -- attemptM never throws an exception attemptM thing_inside = do { (mb_r, lie) <- tryCaptureConstraints thing_inside ; emitConstraints lie -- Debug trace ; when (isNothing mb_r) $ traceTc "attemptM recovering with insoluble constraints" $ (ppr lie) ; return mb_r } ----------------------- recoverM :: TcRn r -- Recovery action; do this if the main one fails -> TcRn r -- Main action: do this first; -- if it generates errors, propagate them all -> TcRn r -- (recoverM recover thing_inside) runs thing_inside -- If thing_inside fails, propagate its errors and insoluble constraints -- and run 'recover' -- If thing_inside succeeds, propagate all its errors and constraints -- -- Can fail, if 'recover' fails recoverM recover thing = do { mb_res <- attemptM thing ; case mb_res of Nothing -> recover Just res -> return res } ----------------------- -- | Drop elements of the input that fail, so the result -- list can be shorter than the argument list mapAndRecoverM :: (a -> TcRn b) -> [a] -> TcRn [b] mapAndRecoverM f xs = do { mb_rs <- mapM (attemptM . f) xs ; return [r | Just r <- mb_rs] } -- | Apply the function to all elements on the input list -- If all succeed, return the list of results -- Otherwise fail, propagating all errors mapAndReportM :: (a -> TcRn b) -> [a] -> TcRn [b] mapAndReportM f xs = do { mb_rs <- mapM (attemptM . f) xs ; when (any isNothing mb_rs) failM ; return [r | Just r <- mb_rs] } -- | The accumulator is not updated if the action fails foldAndRecoverM :: (b -> a -> TcRn b) -> b -> [a] -> TcRn b foldAndRecoverM _ acc [] = return acc foldAndRecoverM f acc (x:xs) = do { mb_r <- attemptM (f acc x) ; case mb_r of Nothing -> foldAndRecoverM f acc xs Just acc' -> foldAndRecoverM f acc' xs } ----------------------- tryTc :: TcRn a -> TcRn (Maybe a, Messages TcRnMessage) -- (tryTc m) executes m, and returns -- Just r, if m succeeds (returning r) -- Nothing, if m fails -- It also returns all the errors and warnings accumulated by m -- It always succeeds (never raises an exception) tryTc thing_inside = capture_messages (attemptM thing_inside) ----------------------- discardErrs :: TcRn a -> TcRn a -- (discardErrs m) runs m, -- discarding all error messages and warnings generated by m -- If m fails, discardErrs fails, and vice versa discardErrs m = do { errs_var <- newTcRef emptyMessages ; setErrsVar errs_var m } ----------------------- tryTcDiscardingErrs :: TcM r -> TcM r -> TcM r -- (tryTcDiscardingErrs recover thing_inside) tries 'thing_inside'; -- if 'main' succeeds with no error messages, it's the answer -- otherwise discard everything from 'main', including errors, -- and try 'recover' instead. tryTcDiscardingErrs recover thing_inside = do { ((mb_res, lie), msgs) <- capture_messages $ capture_constraints $ tcTryM thing_inside ; case mb_res of Just res | not (errorsFound msgs) , not (insolubleWC lie) -> -- 'main' succeeded with no errors do { addMessages msgs -- msgs might still have warnings ; emitConstraints lie ; return res } _ -> -- 'main' failed, or produced an error message recover -- Discard all errors and warnings -- and unsolved constraints entirely } {- ************************************************************************ * * Error message generation (type checker) * * ************************************************************************ The addErrTc functions add an error message, but do not cause failure. The 'M' variants pass a TidyEnv that has already been used to tidy up the message; we then use it to tidy the context messages -} addErrTc :: TcRnMessage -> TcM () addErrTc err_msg = do { env0 <- tcInitTidyEnv ; addErrTcM (env0, err_msg) } addErrTcM :: (TidyEnv, TcRnMessage) -> TcM () addErrTcM (tidy_env, err_msg) = do { ctxt <- getErrCtxt ; loc <- getSrcSpanM ; add_err_tcm tidy_env err_msg loc ctxt } -- The failWith functions add an error message and cause failure failWithTc :: TcRnMessage -> TcM a -- Add an error message and fail failWithTc err_msg = addErrTc err_msg >> failM failWithTcM :: (TidyEnv, TcRnMessage) -> TcM a -- Add an error message and fail failWithTcM local_and_msg = addErrTcM local_and_msg >> failM checkTc :: Bool -> TcRnMessage -> TcM () -- Check that the boolean is true checkTc True _ = return () checkTc False err = failWithTc err checkTcM :: Bool -> (TidyEnv, TcRnMessage) -> TcM () checkTcM True _ = return () checkTcM False err = failWithTcM err failIfTc :: Bool -> TcRnMessage -> TcM () -- Check that the boolean is false failIfTc False _ = return () failIfTc True err = failWithTc err failIfTcM :: Bool -> (TidyEnv, TcRnMessage) -> TcM () -- Check that the boolean is false failIfTcM False _ = return () failIfTcM True err = failWithTcM err -- Warnings have no 'M' variant, nor failure -- | Display a warning if a condition is met. warnIf :: Bool -> TcRnMessage -> TcRn () warnIf is_bad msg -- No need to check any flag here, it will be done in 'diagReasonSeverity'. = when is_bad (addDiagnostic msg) no_err_info :: ErrInfo no_err_info = ErrInfo Outputable.empty Outputable.empty -- | Display a warning if a condition is met. diagnosticTc :: Bool -> TcRnMessage -> TcM () diagnosticTc should_report warn_msg | should_report = addDiagnosticTc warn_msg | otherwise = return () -- | Display a diagnostic if a condition is met. diagnosticTcM :: Bool -> (TidyEnv, TcRnMessage) -> TcM () diagnosticTcM should_report warn_msg | should_report = addDiagnosticTcM warn_msg | otherwise = return () -- | Display a diagnostic in the current context. addDiagnosticTc :: TcRnMessage -> TcM () addDiagnosticTc msg = do { env0 <- tcInitTidyEnv ; addDiagnosticTcM (env0, msg) } -- | Display a diagnostic in a given context. addDiagnosticTcM :: (TidyEnv, TcRnMessage) -> TcM () addDiagnosticTcM (env0, msg) = do { ctxt <- getErrCtxt ; extra <- mkErrInfo env0 ctxt ; let err_info = ErrInfo extra Outputable.empty ; add_diagnostic (TcRnMessageDetailed err_info msg) } -- | A variation of 'addDiagnostic' that takes a function to produce a 'TcRnDsMessage' -- given some additional context about the diagnostic. addDetailedDiagnostic :: (ErrInfo -> TcRnMessage) -> TcM () addDetailedDiagnostic mkMsg = do loc <- getSrcSpanM printer <- getPrintUnqualified !diag_opts <- initDiagOpts <$> getDynFlags env0 <- tcInitTidyEnv ctxt <- getErrCtxt err_info <- mkErrInfo env0 ctxt reportDiagnostic (mkMsgEnvelope diag_opts loc printer (mkMsg (ErrInfo err_info empty))) addTcRnDiagnostic :: TcRnMessage -> TcM () addTcRnDiagnostic msg = do loc <- getSrcSpanM mkTcRnMessage loc msg >>= reportDiagnostic -- | Display a diagnostic for the current source location, taken from -- the 'TcRn' monad. addDiagnostic :: TcRnMessage -> TcRn () addDiagnostic msg = add_diagnostic (TcRnMessageDetailed no_err_info msg) -- | Display a diagnostic for a given source location. addDiagnosticAt :: SrcSpan -> TcRnMessage -> TcRn () addDiagnosticAt loc msg = do unit_state <- hsc_units <$> getTopEnv let dia = TcRnMessageDetailed no_err_info msg mkTcRnMessage loc (TcRnMessageWithInfo unit_state dia) >>= reportDiagnostic -- | Display a diagnostic, with an optional flag, for the current source -- location. add_diagnostic :: TcRnMessageDetailed -> TcRn () add_diagnostic msg = do { loc <- getSrcSpanM ; unit_state <- hsc_units <$> getTopEnv ; mkTcRnMessage loc (TcRnMessageWithInfo unit_state msg) >>= reportDiagnostic } {- ----------------------------------- Other helper functions -} add_err_tcm :: TidyEnv -> TcRnMessage -> SrcSpan -> [ErrCtxt] -> TcM () add_err_tcm tidy_env msg loc ctxt = do { err_info <- mkErrInfo tidy_env ctxt ; add_long_err_at loc (TcRnMessageDetailed (ErrInfo err_info Outputable.empty) msg) } mkErrInfo :: TidyEnv -> [ErrCtxt] -> TcM SDoc -- Tidy the error info, trimming excessive contexts mkErrInfo env ctxts -- = do -- dbg <- hasPprDebug <$> getDynFlags -- if dbg -- In -dppr-debug style the output -- then return empty -- just becomes too voluminous -- else go dbg 0 env ctxts = go False 0 env ctxts where go :: Bool -> Int -> TidyEnv -> [ErrCtxt] -> TcM SDoc go _ _ _ [] = return empty go dbg n env ((is_landmark, ctxt) : ctxts) | is_landmark || n < mAX_CONTEXTS -- Too verbose || dbg = do { (env', msg) <- ctxt env ; let n' = if is_landmark then n else n+1 ; rest <- go dbg n' env' ctxts ; return (msg $$ rest) } | otherwise = go dbg n env ctxts mAX_CONTEXTS :: Int -- No more than this number of non-landmark contexts mAX_CONTEXTS = 3 -- debugTc is useful for monadic debugging code debugTc :: TcM () -> TcM () debugTc thing | debugIsOn = thing | otherwise = return () {- ************************************************************************ * * Type constraints * * ************************************************************************ -} addTopEvBinds :: Bag EvBind -> TcM a -> TcM a addTopEvBinds new_ev_binds thing_inside =updGblEnv upd_env thing_inside where upd_env tcg_env = tcg_env { tcg_ev_binds = tcg_ev_binds tcg_env `unionBags` new_ev_binds } newTcEvBinds :: TcM EvBindsVar newTcEvBinds = do { binds_ref <- newTcRef emptyEvBindMap ; tcvs_ref <- newTcRef emptyVarSet ; uniq <- newUnique ; traceTc "newTcEvBinds" (text "unique =" <+> ppr uniq) ; return (EvBindsVar { ebv_binds = binds_ref , ebv_tcvs = tcvs_ref , ebv_uniq = uniq }) } -- | Creates an EvBindsVar incapable of holding any bindings. It still -- tracks covar usages (see comments on ebv_tcvs in "GHC.Tc.Types.Evidence"), thus -- must be made monadically newNoTcEvBinds :: TcM EvBindsVar newNoTcEvBinds = do { tcvs_ref <- newTcRef emptyVarSet ; uniq <- newUnique ; traceTc "newNoTcEvBinds" (text "unique =" <+> ppr uniq) ; return (CoEvBindsVar { ebv_tcvs = tcvs_ref , ebv_uniq = uniq }) } cloneEvBindsVar :: EvBindsVar -> TcM EvBindsVar -- Clone the refs, so that any binding created when -- solving don't pollute the original cloneEvBindsVar ebv@(EvBindsVar {}) = do { binds_ref <- newTcRef emptyEvBindMap ; tcvs_ref <- newTcRef emptyVarSet ; return (ebv { ebv_binds = binds_ref , ebv_tcvs = tcvs_ref }) } cloneEvBindsVar ebv@(CoEvBindsVar {}) = do { tcvs_ref <- newTcRef emptyVarSet ; return (ebv { ebv_tcvs = tcvs_ref }) } getTcEvTyCoVars :: EvBindsVar -> TcM TyCoVarSet getTcEvTyCoVars ev_binds_var = readTcRef (ebv_tcvs ev_binds_var) getTcEvBindsMap :: EvBindsVar -> TcM EvBindMap getTcEvBindsMap (EvBindsVar { ebv_binds = ev_ref }) = readTcRef ev_ref getTcEvBindsMap (CoEvBindsVar {}) = return emptyEvBindMap setTcEvBindsMap :: EvBindsVar -> EvBindMap -> TcM () setTcEvBindsMap (EvBindsVar { ebv_binds = ev_ref }) binds = writeTcRef ev_ref binds setTcEvBindsMap v@(CoEvBindsVar {}) ev_binds | isEmptyEvBindMap ev_binds = return () | otherwise = pprPanic "setTcEvBindsMap" (ppr v $$ ppr ev_binds) addTcEvBind :: EvBindsVar -> EvBind -> TcM () -- Add a binding to the TcEvBinds by side effect addTcEvBind (EvBindsVar { ebv_binds = ev_ref, ebv_uniq = u }) ev_bind = do { traceTc "addTcEvBind" $ ppr u $$ ppr ev_bind ; bnds <- readTcRef ev_ref ; writeTcRef ev_ref (extendEvBinds bnds ev_bind) } addTcEvBind (CoEvBindsVar { ebv_uniq = u }) ev_bind = pprPanic "addTcEvBind CoEvBindsVar" (ppr ev_bind $$ ppr u) chooseUniqueOccTc :: (OccSet -> OccName) -> TcM OccName chooseUniqueOccTc fn = do { env <- getGblEnv ; let dfun_n_var = tcg_dfun_n env ; set <- readTcRef dfun_n_var ; let occ = fn set ; writeTcRef dfun_n_var (extendOccSet set occ) ; return occ } getConstraintVar :: TcM (TcRef WantedConstraints) getConstraintVar = do { env <- getLclEnv; return (tcl_lie env) } setConstraintVar :: TcRef WantedConstraints -> TcM a -> TcM a setConstraintVar lie_var = updLclEnv (\ env -> env { tcl_lie = lie_var }) emitStaticConstraints :: WantedConstraints -> TcM () emitStaticConstraints static_lie = do { gbl_env <- getGblEnv ; updTcRef (tcg_static_wc gbl_env) (`andWC` static_lie) } emitConstraints :: WantedConstraints -> TcM () emitConstraints ct | isEmptyWC ct = return () | otherwise = do { lie_var <- getConstraintVar ; updTcRef lie_var (`andWC` ct) } emitSimple :: Ct -> TcM () emitSimple ct = do { lie_var <- getConstraintVar ; updTcRef lie_var (`addSimples` unitBag ct) } emitSimples :: Cts -> TcM () emitSimples cts = do { lie_var <- getConstraintVar ; updTcRef lie_var (`addSimples` cts) } emitImplication :: Implication -> TcM () emitImplication ct = do { lie_var <- getConstraintVar ; updTcRef lie_var (`addImplics` unitBag ct) } emitImplications :: Bag Implication -> TcM () emitImplications ct = unless (isEmptyBag ct) $ do { lie_var <- getConstraintVar ; updTcRef lie_var (`addImplics` ct) } emitInsoluble :: Ct -> TcM () emitInsoluble ct = do { traceTc "emitInsoluble" (ppr ct) ; lie_var <- getConstraintVar ; updTcRef lie_var (`addInsols` unitBag ct) } emitDelayedErrors :: Bag DelayedError -> TcM () emitDelayedErrors errs = do { traceTc "emitDelayedErrors" (ppr errs) ; lie_var <- getConstraintVar ; updTcRef lie_var (`addDelayedErrors` errs)} emitHole :: Hole -> TcM () emitHole hole = do { traceTc "emitHole" (ppr hole) ; lie_var <- getConstraintVar ; updTcRef lie_var (`addHoles` unitBag hole) } emitHoles :: Bag Hole -> TcM () emitHoles holes = do { traceTc "emitHoles" (ppr holes) ; lie_var <- getConstraintVar ; updTcRef lie_var (`addHoles` holes) } emitNotConcreteError :: NotConcreteError -> TcM () emitNotConcreteError err = do { traceTc "emitNotConcreteError" (ppr err) ; lie_var <- getConstraintVar ; updTcRef lie_var (`addNotConcreteError` err) } -- | Throw out any constraints emitted by the thing_inside discardConstraints :: TcM a -> TcM a discardConstraints thing_inside = fst <$> captureConstraints thing_inside -- | The name says it all. The returned TcLevel is the *inner* TcLevel. pushLevelAndCaptureConstraints :: TcM a -> TcM (TcLevel, WantedConstraints, a) pushLevelAndCaptureConstraints thing_inside = do { tclvl <- getTcLevel ; let tclvl' = pushTcLevel tclvl ; traceTc "pushLevelAndCaptureConstraints {" (ppr tclvl') ; (res, lie) <- updLclEnv (\env -> env { tcl_tclvl = tclvl' }) $ captureConstraints thing_inside ; traceTc "pushLevelAndCaptureConstraints }" (ppr tclvl') ; return (tclvl', lie, res) } pushTcLevelM_ :: TcM a -> TcM a pushTcLevelM_ x = updLclEnv (\ env -> env { tcl_tclvl = pushTcLevel (tcl_tclvl env) }) x pushTcLevelM :: TcM a -> TcM (TcLevel, a) -- See Note [TcLevel assignment] in GHC.Tc.Utils.TcType pushTcLevelM thing_inside = do { tclvl <- getTcLevel ; let tclvl' = pushTcLevel tclvl ; res <- updLclEnv (\env -> env { tcl_tclvl = tclvl' }) thing_inside ; return (tclvl', res) } getTcLevel :: TcM TcLevel getTcLevel = do { env <- getLclEnv ; return (tcl_tclvl env) } setTcLevel :: TcLevel -> TcM a -> TcM a setTcLevel tclvl thing_inside = updLclEnv (\env -> env { tcl_tclvl = tclvl }) thing_inside isTouchableTcM :: TcTyVar -> TcM Bool isTouchableTcM tv = do { lvl <- getTcLevel ; return (isTouchableMetaTyVar lvl tv) } getLclTypeEnv :: TcM TcTypeEnv getLclTypeEnv = do { env <- getLclEnv; return (tcl_env env) } setLclTypeEnv :: TcLclEnv -> TcM a -> TcM a -- Set the local type envt, but do *not* disturb other fields, -- notably the lie_var setLclTypeEnv lcl_env thing_inside = updLclEnv upd thing_inside where upd env = env { tcl_env = tcl_env lcl_env } traceTcConstraints :: String -> TcM () traceTcConstraints msg = do { lie_var <- getConstraintVar ; lie <- readTcRef lie_var ; traceOptTcRn Opt_D_dump_tc_trace $ hang (text (msg ++ ": LIE:")) 2 (ppr lie) } data IsExtraConstraint = YesExtraConstraint | NoExtraConstraint instance Outputable IsExtraConstraint where ppr YesExtraConstraint = text "YesExtraConstraint" ppr NoExtraConstraint = text "NoExtraConstraint" emitAnonTypeHole :: IsExtraConstraint -> TcTyVar -> TcM () emitAnonTypeHole extra_constraints tv = do { ct_loc <- getCtLocM (TypeHoleOrigin occ) Nothing ; let hole = Hole { hole_sort = sort , hole_occ = occ , hole_ty = mkTyVarTy tv , hole_loc = ct_loc } ; emitHole hole } where occ = mkTyVarOcc "_" sort | YesExtraConstraint <- extra_constraints = ConstraintHole | otherwise = TypeHole emitNamedTypeHole :: (Name, TcTyVar) -> TcM () emitNamedTypeHole (name, tv) = do { ct_loc <- setSrcSpan (nameSrcSpan name) $ getCtLocM (TypeHoleOrigin occ) Nothing ; let hole = Hole { hole_sort = TypeHole , hole_occ = occ , hole_ty = mkTyVarTy tv , hole_loc = ct_loc } ; emitHole hole } where occ = nameOccName name {- Note [Constraints and errors] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider this (#12124): foo :: Maybe Int foo = return (case Left 3 of Left -> 1 -- Hard error here! _ -> 0) The call to 'return' will generate a (Monad m) wanted constraint; but then there'll be "hard error" (i.e. an exception in the TcM monad), from the unsaturated Left constructor pattern. We'll recover in tcPolyBinds, using recoverM. But then the final tcSimplifyTop will see that (Monad m) constraint, with 'm' utterly un-filled-in, and will emit a misleading error message. The underlying problem is that an exception interrupts the constraint gathering process. Bottom line: if we have an exception, it's best simply to discard any gathered constraints. Hence in 'attemptM' we capture the constraints in a fresh variable, and only emit them into the surrounding context if we exit normally. If an exception is raised, simply discard the collected constraints... we have a hard error to report. So this capture-the-emit dance isn't as stupid as it looks :-). However suppose we throw an exception inside an invocation of captureConstraints, and discard all the constraints. Some of those constraints might be "variable out of scope" Hole constraints, and that might have been the actual original cause of the exception! For example (#12529): f = p @ Int Here 'p' is out of scope, so we get an insoluble Hole constraint. But the visible type application fails in the monad (throws an exception). We must not discard the out-of-scope error. It's distressingly delicate though: * If we discard too /many/ constraints we may fail to report the error that led us to interrupte the constraint gathering process. One particular example "variable out of scope" Hole constraints. For example (#12529): f = p @ Int Here 'p' is out of scope, so we get an insoluble Hole constraint. But the visible type application fails in the monad (throws an exception). We must not discard the out-of-scope error. Also GHC.Tc.Solver.simplifyAndEmitFlatConstraints may fail having emitted some constraints with skolem-escape problems. * If we discard too /few/ constraints, we may get the misleading class constraints mentioned above. But we may /also/ end up taking constraints built at some inner level, and emitting them at some outer level, and then breaking the TcLevel invariants See Note [TcLevel invariants] in GHC.Tc.Utils.TcType So dropMisleading has a horridly ad-hoc structure. It keeps only /insoluble/ flat constraints (which are unlikely to very visibly trip up on the TcLevel invariant, but all /implication/ constraints (except the class constraints inside them). The implication constraints are OK because they set the ambient level before attempting to solve any inner constraints. Ugh! I hate this. But it seems to work. However note that freshly-generated constraints like (Int ~ Bool), or ((a -> b) ~ Int) are all CNonCanonical, and hence won't be flagged as insoluble. The constraint solver does that. So they'll be discarded. That's probably ok; but see th/5358 as a not-so-good example: t1 :: Int t1 x = x -- Manifestly wrong foo = $(...raises exception...) We report the exception, but not the bug in t1. Oh well. Possible solution: make GHC.Tc.Utils.Unify.uType spot manifestly-insoluble constraints. ************************************************************************ * * Template Haskell context * * ************************************************************************ -} recordThUse :: TcM () recordThUse = do { env <- getGblEnv; writeTcRef (tcg_th_used env) True } recordThSpliceUse :: TcM () recordThSpliceUse = do { env <- getGblEnv; writeTcRef (tcg_th_splice_used env) True } recordThNeededRuntimeDeps :: [Linkable] -> PkgsLoaded -> TcM () recordThNeededRuntimeDeps new_links new_pkgs = do { env <- getGblEnv ; updTcRef (tcg_th_needed_deps env) $ \(needed_links, needed_pkgs) -> let links = new_links ++ needed_links !pkgs = plusUDFM needed_pkgs new_pkgs in (links, pkgs) } keepAlive :: Name -> TcRn () -- Record the name in the keep-alive set keepAlive name = do { env <- getGblEnv ; traceRn "keep alive" (ppr name) ; updTcRef (tcg_keep env) (`extendNameSet` name) } getStage :: TcM ThStage getStage = do { env <- getLclEnv; return (tcl_th_ctxt env) } getStageAndBindLevel :: Name -> TcRn (Maybe (TopLevelFlag, ThLevel, ThStage)) getStageAndBindLevel name = do { env <- getLclEnv; ; case lookupNameEnv (tcl_th_bndrs env) name of Nothing -> return Nothing Just (top_lvl, bind_lvl) -> return (Just (top_lvl, bind_lvl, tcl_th_ctxt env)) } setStage :: ThStage -> TcM a -> TcRn a setStage s = updLclEnv (\ env -> env { tcl_th_ctxt = s }) -- | Adds the given modFinalizers to the global environment and set them to use -- the current local environment. addModFinalizersWithLclEnv :: ThModFinalizers -> TcM () addModFinalizersWithLclEnv mod_finalizers = do lcl_env <- getLclEnv th_modfinalizers_var <- fmap tcg_th_modfinalizers getGblEnv updTcRef th_modfinalizers_var $ \fins -> (lcl_env, mod_finalizers) : fins {- ************************************************************************ * * Safe Haskell context * * ************************************************************************ -} -- | Mark that safe inference has failed -- See Note [Safe Haskell Overlapping Instances Implementation] -- although this is used for more than just that failure case. recordUnsafeInfer :: Messages TcRnMessage -> TcM () recordUnsafeInfer msgs = getGblEnv >>= \env -> do writeTcRef (tcg_safe_infer env) False writeTcRef (tcg_safe_infer_reasons env) msgs -- | Figure out the final correct safe haskell mode finalSafeMode :: DynFlags -> TcGblEnv -> IO SafeHaskellMode finalSafeMode dflags tcg_env = do safeInf <- readIORef (tcg_safe_infer tcg_env) return $ case safeHaskell dflags of Sf_None | safeInferOn dflags && safeInf -> Sf_SafeInferred | otherwise -> Sf_None s -> s -- | Switch instances to safe instances if we're in Safe mode. fixSafeInstances :: SafeHaskellMode -> [ClsInst] -> [ClsInst] fixSafeInstances sfMode | sfMode /= Sf_Safe && sfMode /= Sf_SafeInferred = id fixSafeInstances _ = map fixSafe where fixSafe inst = let new_flag = (is_flag inst) { isSafeOverlap = True } in inst { is_flag = new_flag } {- ************************************************************************ * * Stuff for the renamer's local env * * ************************************************************************ -} getLocalRdrEnv :: RnM LocalRdrEnv getLocalRdrEnv = do { env <- getLclEnv; return (tcl_rdr env) } setLocalRdrEnv :: LocalRdrEnv -> RnM a -> RnM a setLocalRdrEnv rdr_env thing_inside = updLclEnv (\env -> env {tcl_rdr = rdr_env}) thing_inside {- ************************************************************************ * * Stuff for interface decls * * ************************************************************************ -} mkIfLclEnv :: Module -> SDoc -> IsBootInterface -> IfLclEnv mkIfLclEnv mod loc boot = IfLclEnv { if_mod = mod, if_loc = loc, if_boot = boot, if_nsubst = Nothing, if_implicits_env = Nothing, if_tv_env = emptyFsEnv, if_id_env = emptyFsEnv } -- | Run an 'IfG' (top-level interface monad) computation inside an existing -- 'TcRn' (typecheck-renaming monad) computation by initializing an 'IfGblEnv' -- based on 'TcGblEnv'. initIfaceTcRn :: IfG a -> TcRn a initIfaceTcRn thing_inside = do { tcg_env <- getGblEnv ; hsc_env <- getTopEnv -- bangs to avoid leaking the envs (#19356) ; let !mhome_unit = hsc_home_unit_maybe hsc_env !knot_vars = tcg_type_env_var tcg_env -- When we are instantiating a signature, we DEFINITELY -- do not want to knot tie. is_instantiate = fromMaybe False (isHomeUnitInstantiating <$> mhome_unit) ; let { if_env = IfGblEnv { if_doc = text "initIfaceTcRn", if_rec_types = if is_instantiate then emptyKnotVars else readTcRef <$> knot_vars } } ; setEnvs (if_env, ()) thing_inside } -- | 'initIfaceLoad' can be used when there's no chance that the action will -- call 'typecheckIface' when inside a module loop and hence 'tcIfaceGlobal'. initIfaceLoad :: HscEnv -> IfG a -> IO a initIfaceLoad hsc_env do_this = do let gbl_env = IfGblEnv { if_doc = text "initIfaceLoad", if_rec_types = emptyKnotVars } initTcRnIf 'i' (hsc_env { hsc_type_env_vars = emptyKnotVars }) gbl_env () do_this -- | This is used when we are doing to call 'typecheckModule' on an 'ModIface', -- if it's part of a loop with some other modules then we need to use their -- IORef TypeEnv vars when typechecking but crucially not our own. initIfaceLoadModule :: HscEnv -> Module -> IfG a -> IO a initIfaceLoadModule hsc_env this_mod do_this = do let gbl_env = IfGblEnv { if_doc = text "initIfaceLoadModule", if_rec_types = readTcRef <$> knotVarsWithout this_mod (hsc_type_env_vars hsc_env) } initTcRnIf 'i' hsc_env gbl_env () do_this initIfaceCheck :: SDoc -> HscEnv -> IfG a -> IO a -- Used when checking the up-to-date-ness of the old Iface -- Initialise the environment with no useful info at all initIfaceCheck doc hsc_env do_this = do let gbl_env = IfGblEnv { if_doc = text "initIfaceCheck" <+> doc, if_rec_types = readTcRef <$> hsc_type_env_vars hsc_env } initTcRnIf 'i' hsc_env gbl_env () do_this initIfaceLcl :: Module -> SDoc -> IsBootInterface -> IfL a -> IfM lcl a initIfaceLcl mod loc_doc hi_boot_file thing_inside = setLclEnv (mkIfLclEnv mod loc_doc hi_boot_file) thing_inside -- | Initialize interface typechecking, but with a 'NameShape' -- to apply when typechecking top-level 'OccName's (see -- 'lookupIfaceTop') initIfaceLclWithSubst :: Module -> SDoc -> IsBootInterface -> NameShape -> IfL a -> IfM lcl a initIfaceLclWithSubst mod loc_doc hi_boot_file nsubst thing_inside = setLclEnv ((mkIfLclEnv mod loc_doc hi_boot_file) { if_nsubst = Just nsubst }) thing_inside getIfModule :: IfL Module getIfModule = do { env <- getLclEnv; return (if_mod env) } -------------------- failIfM :: SDoc -> IfL a -- The Iface monad doesn't have a place to accumulate errors, so we -- just fall over fast if one happens; it "shouldn't happen". -- We use IfL here so that we can get context info out of the local env failIfM msg = do env <- getLclEnv let full_msg = (if_loc env <> colon) $$ nest 2 msg logger <- getLogger liftIO (logMsg logger MCFatal noSrcSpan $ withPprStyle defaultErrStyle full_msg) failM -------------------- -- | Run thing_inside in an interleaved thread. -- It shares everything with the parent thread, so this is DANGEROUS. -- -- It throws an error if the computation fails -- -- It's used for lazily type-checking interface -- signatures, which is pretty benign. -- -- See Note [Masking exceptions in forkM] forkM :: SDoc -> IfL a -> IfL a forkM doc thing_inside = unsafeInterleaveM $ uninterruptibleMaskM_ $ do { traceIf (text "Starting fork {" <+> doc) ; mb_res <- tryM $ updLclEnv (\env -> env { if_loc = if_loc env $$ doc }) $ thing_inside ; case mb_res of Right r -> do { traceIf (text "} ending fork" <+> doc) ; return r } Left exn -> do { -- Bleat about errors in the forked thread, if -ddump-if-trace is on -- Otherwise we silently discard errors. Errors can legitimately -- happen when compiling interface signatures. whenDOptM Opt_D_dump_if_trace $ do logger <- getLogger let msg = hang (text "forkM failed:" <+> doc) 2 (text (show exn)) liftIO $ logMsg logger MCFatal noSrcSpan $ withPprStyle defaultErrStyle msg ; traceIf (text "} ending fork (badly)" <+> doc) ; pgmError "Cannot continue after interface file error" } } setImplicitEnvM :: TypeEnv -> IfL a -> IfL a setImplicitEnvM tenv m = updLclEnv (\lcl -> lcl { if_implicits_env = Just tenv }) m {- Note [Masking exceptions in forkM] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ When using GHC-as-API it must be possible to interrupt snippets of code executed using runStmt (#1381). Since commit 02c4ab04 this is almost possible by throwing an asynchronous interrupt to the GHC thread. However, there is a subtle problem: runStmt first typechecks the code before running it, and the exception might interrupt the type checker rather than the code. Moreover, the typechecker might be inside an unsafeInterleaveIO (through forkM), and more importantly might be inside an exception handler inside that unsafeInterleaveIO. If that is the case, the exception handler will rethrow the asynchronous exception as a synchronous exception, and the exception will end up as the value of the unsafeInterleaveIO thunk (see #8006 for a detailed discussion). We don't currently know a general solution to this problem, but we can use uninterruptibleMask_ to avoid the situation. -} -- | Get the next cost centre index associated with a given name. getCCIndexM :: (gbl -> TcRef CostCentreState) -> FastString -> TcRnIf gbl lcl CostCentreIndex getCCIndexM get_ccs nm = do env <- getGblEnv let cc_st_ref = get_ccs env cc_st <- readTcRef cc_st_ref let (idx, cc_st') = getCCIndex nm cc_st writeTcRef cc_st_ref cc_st' return idx -- | See 'getCCIndexM'. getCCIndexTcM :: FastString -> TcM CostCentreIndex getCCIndexTcM = getCCIndexM tcg_cc_st