{- (c) The University of Glasgow 2006-2012 (c) The GRASP Project, Glasgow University, 1992-2002 Various types used during typechecking, please see TcRnMonad as well for operations on these types. You probably want to import it, instead of this module. All the monads exported here are built on top of the same IOEnv monad. The monad functions like a Reader monad in the way it passes the environment around. This is done to allow the environment to be manipulated in a stack like fashion when entering expressions... etc. For state that is global and should be returned at the end (e.g not part of the stack mechanism), you should use a TcRef (= IORef) to store them. -} {-# LANGUAGE CPP, DeriveFunctor, ExistentialQuantification, GeneralizedNewtypeDeriving, ViewPatterns #-} module TcRnTypes( TcRnIf, TcRn, TcM, RnM, IfM, IfL, IfG, -- The monad is opaque outside this module TcRef, -- The environment types Env(..), TcGblEnv(..), TcLclEnv(..), setLclEnvTcLevel, getLclEnvTcLevel, setLclEnvLoc, getLclEnvLoc, IfGblEnv(..), IfLclEnv(..), tcVisibleOrphanMods, -- Frontend types (shouldn't really be here) FrontendResult(..), -- Renamer types ErrCtxt, RecFieldEnv, pushErrCtxt, pushErrCtxtSameOrigin, ImportAvails(..), emptyImportAvails, plusImportAvails, WhereFrom(..), mkModDeps, modDepsElts, -- Typechecker types TcTypeEnv, TcBinderStack, TcBinder(..), TcTyThing(..), PromotionErr(..), IdBindingInfo(..), ClosedTypeId, RhsNames, IsGroupClosed(..), SelfBootInfo(..), pprTcTyThingCategory, pprPECategory, CompleteMatch(..), -- Desugaring types DsM, DsLclEnv(..), DsGblEnv(..), DsMetaEnv, DsMetaVal(..), CompleteMatchMap, mkCompleteMatchMap, extendCompleteMatchMap, -- Template Haskell ThStage(..), SpliceType(..), PendingStuff(..), topStage, topAnnStage, topSpliceStage, ThLevel, impLevel, outerLevel, thLevel, ForeignSrcLang(..), -- Arrows ArrowCtxt(..), -- TcSigInfo TcSigFun, TcSigInfo(..), TcIdSigInfo(..), TcIdSigInst(..), TcPatSynInfo(..), isPartialSig, hasCompleteSig, -- Misc other types TcId, TcIdSet, Hole(..), holeOcc, NameShape(..), removeBindingShadowing, -- Constraint solver plugins TcPlugin(..), TcPluginResult(..), TcPluginSolver, TcPluginM, runTcPluginM, unsafeTcPluginTcM, getEvBindsTcPluginM, -- Role annotations RoleAnnotEnv, emptyRoleAnnotEnv, mkRoleAnnotEnv, lookupRoleAnnot, getRoleAnnots ) where #include "HsVersions.h" import GhcPrelude import GHC.Hs import HscTypes import TcEvidence import Type import TyCon ( TyCon, tyConKind ) import PatSyn ( PatSyn ) import Id ( idType, idName ) import FieldLabel ( FieldLabel ) import TcType import Constraint import TcOrigin import Annotations import InstEnv import FamInstEnv import {-# SOURCE #-} GHC.HsToCore.PmCheck.Types (Delta) import IOEnv import RdrName import Name import NameEnv import NameSet import Avail import Var import VarEnv import Module import SrcLoc import VarSet import ErrUtils import UniqFM import BasicTypes import Bag import DynFlags import Outputable import ListSetOps import Fingerprint import Util import PrelNames ( isUnboundName ) import CostCentreState import Control.Monad (ap) import qualified Control.Monad.Fail as MonadFail import Data.Set ( Set ) import qualified Data.Set as S import Data.List ( sort ) import Data.Map ( Map ) import Data.Dynamic ( Dynamic ) import Data.Typeable ( TypeRep ) import Data.Maybe ( mapMaybe ) import GHCi.Message import GHCi.RemoteTypes import {-# SOURCE #-} TcHoleFitTypes ( HoleFitPlugin ) import qualified Language.Haskell.TH as TH -- | A 'NameShape' is a substitution on 'Name's that can be used -- to refine the identities of a hole while we are renaming interfaces -- (see 'RnModIface'). Specifically, a 'NameShape' for -- 'ns_module_name' @A@, defines a mapping from @{A.T}@ -- (for some 'OccName' @T@) to some arbitrary other 'Name'. -- -- The most intruiging thing about a 'NameShape', however, is -- how it's constructed. A 'NameShape' is *implied* by the -- exported 'AvailInfo's of the implementor of an interface: -- if an implementor of signature @<H>@ exports @M.T@, you implicitly -- define a substitution from @{H.T}@ to @M.T@. So a 'NameShape' -- is computed from the list of 'AvailInfo's that are exported -- by the implementation of a module, or successively merged -- together by the export lists of signatures which are joining -- together. -- -- It's not the most obvious way to go about doing this, but it -- does seem to work! -- -- NB: Can't boot this and put it in NameShape because then we -- start pulling in too many DynFlags things. data NameShape = NameShape { ns_mod_name :: ModuleName, ns_exports :: [AvailInfo], ns_map :: OccEnv Name } {- ************************************************************************ * * Standard monad definition for TcRn All the combinators for the monad can be found in TcRnMonad * * ************************************************************************ The monad itself has to be defined here, because it is mentioned by ErrCtxt -} type TcRnIf a b = IOEnv (Env a b) type TcRn = TcRnIf TcGblEnv TcLclEnv -- Type inference type IfM lcl = TcRnIf IfGblEnv lcl -- Iface stuff type IfG = IfM () -- Top level type IfL = IfM IfLclEnv -- Nested type DsM = TcRnIf DsGblEnv DsLclEnv -- Desugaring -- TcRn is the type-checking and renaming monad: the main monad that -- most type-checking takes place in. The global environment is -- 'TcGblEnv', which tracks all of the top-level type-checking -- information we've accumulated while checking a module, while the -- local environment is 'TcLclEnv', which tracks local information as -- we move inside expressions. -- | Historical "renaming monad" (now it's just 'TcRn'). type RnM = TcRn -- | Historical "type-checking monad" (now it's just 'TcRn'). type TcM = TcRn -- We 'stack' these envs through the Reader like monad infrastructure -- as we move into an expression (although the change is focused in -- the lcl type). data Env gbl lcl = Env { env_top :: !HscEnv, -- Top-level stuff that never changes -- Includes all info about imported things -- BangPattern is to fix leak, see #15111 env_um :: !Char, -- Mask for Uniques env_gbl :: gbl, -- Info about things defined at the top level -- of the module being compiled env_lcl :: lcl -- Nested stuff; changes as we go into } instance ContainsDynFlags (Env gbl lcl) where extractDynFlags env = hsc_dflags (env_top env) instance ContainsModule gbl => ContainsModule (Env gbl lcl) where extractModule env = extractModule (env_gbl env) {- ************************************************************************ * * The interface environments Used when dealing with IfaceDecls * * ************************************************************************ -} data IfGblEnv = IfGblEnv { -- Some information about where this environment came from; -- useful for debugging. if_doc :: SDoc, -- The type environment for the module being compiled, -- in case the interface refers back to it via a reference that -- was originally a hi-boot file. -- We need the module name so we can test when it's appropriate -- to look in this env. -- See Note [Tying the knot] in TcIface if_rec_types :: Maybe (Module, IfG TypeEnv) -- Allows a read effect, so it can be in a mutable -- variable; c.f. handling the external package type env -- Nothing => interactive stuff, no loops possible } data IfLclEnv = IfLclEnv { -- The module for the current IfaceDecl -- So if we see f = \x -> x -- it means M.f = \x -> x, where M is the if_mod -- NB: This is a semantic module, see -- Note [Identity versus semantic module] if_mod :: Module, -- Whether or not the IfaceDecl came from a boot -- file or not; we'll use this to choose between -- NoUnfolding and BootUnfolding if_boot :: Bool, -- The field is used only for error reporting -- if (say) there's a Lint error in it if_loc :: SDoc, -- Where the interface came from: -- .hi file, or GHCi state, or ext core -- plus which bit is currently being examined if_nsubst :: Maybe NameShape, -- This field is used to make sure "implicit" declarations -- (anything that cannot be exported in mi_exports) get -- wired up correctly in typecheckIfacesForMerging. Most -- of the time it's @Nothing@. See Note [Resolving never-exported Names in TcIface] -- in TcIface. if_implicits_env :: Maybe TypeEnv, if_tv_env :: FastStringEnv TyVar, -- Nested tyvar bindings if_id_env :: FastStringEnv Id -- Nested id binding } {- ************************************************************************ * * Desugarer monad * * ************************************************************************ Now the mondo monad magic (yes, @DsM@ is a silly name)---carry around a @UniqueSupply@ and some annotations, which presumably include source-file location information: -} data DsGblEnv = DsGblEnv { ds_mod :: Module -- For SCC profiling , ds_fam_inst_env :: FamInstEnv -- Like tcg_fam_inst_env , ds_unqual :: PrintUnqualified , ds_msgs :: IORef Messages -- Warning messages , ds_if_env :: (IfGblEnv, IfLclEnv) -- Used for looking up global, -- possibly-imported things , ds_complete_matches :: CompleteMatchMap -- Additional complete pattern matches , ds_cc_st :: IORef CostCentreState -- Tracking indices for cost centre annotations } instance ContainsModule DsGblEnv where extractModule = ds_mod data DsLclEnv = DsLclEnv { dsl_meta :: DsMetaEnv, -- Template Haskell bindings dsl_loc :: RealSrcSpan, -- To put in pattern-matching error msgs -- See Note [Note [Type and Term Equality Propagation] in Check.hs -- The oracle state Delta is augmented as we walk inwards, -- through each pattern match in turn dsl_delta :: Delta } -- Inside [| |] brackets, the desugarer looks -- up variables in the DsMetaEnv type DsMetaEnv = NameEnv DsMetaVal data DsMetaVal = DsBound Id -- Bound by a pattern inside the [| |]. -- Will be dynamically alpha renamed. -- The Id has type THSyntax.Var | DsSplice (HsExpr GhcTc) -- These bindings are introduced by -- the PendingSplices on a HsBracketOut {- ************************************************************************ * * Global typechecker environment * * ************************************************************************ -} -- | 'FrontendResult' describes the result of running the -- frontend of a Haskell module. Usually, you'll get -- a 'FrontendTypecheck', since running the frontend involves -- typechecking a program, but for an hs-boot merge you'll -- just get a ModIface, since no actual typechecking occurred. -- -- This data type really should be in HscTypes, but it needs -- to have a TcGblEnv which is only defined here. data FrontendResult = FrontendTypecheck TcGblEnv -- Note [Identity versus semantic module] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- When typechecking an hsig file, it is convenient to keep track -- of two different "this module" identifiers: -- -- - The IDENTITY module is simply thisPackage + the module -- name; i.e. it uniquely *identifies* the interface file -- we're compiling. For example, p[A=<A>]:A is an -- identity module identifying the requirement named A -- from library p. -- -- - The SEMANTIC module, which is the actual module that -- this signature is intended to represent (e.g. if -- we have a identity module p[A=base:Data.IORef]:A, -- then the semantic module is base:Data.IORef) -- -- Which one should you use? -- -- - In the desugarer and later phases of compilation, -- identity and semantic modules coincide, since we never compile -- signatures (we just generate blank object files for -- hsig files.) -- -- A corrolary of this is that the following invariant holds at any point -- past desugaring, -- -- if I have a Module, this_mod, in hand representing the module -- currently being compiled, -- then moduleUnitId this_mod == thisPackage dflags -- -- - For any code involving Names, we want semantic modules. -- See lookupIfaceTop in IfaceEnv, mkIface and addFingerprints -- in MkIface, and tcLookupGlobal in TcEnv -- -- - When reading interfaces, we want the identity module to -- identify the specific interface we want (such interfaces -- should never be loaded into the EPS). However, if a -- hole module <A> is requested, we look for A.hi -- in the home library we are compiling. (See LoadIface.) -- Similarly, in RnNames we check for self-imports using -- identity modules, to allow signatures to import their implementor. -- -- - For recompilation avoidance, you want the identity module, -- since that will actually say the specific interface you -- want to track (and recompile if it changes) -- | 'TcGblEnv' describes the top-level of the module at the -- point at which the typechecker is finished work. -- It is this structure that is handed on to the desugarer -- For state that needs to be updated during the typechecking -- phase and returned at end, use a 'TcRef' (= 'IORef'). data TcGblEnv = TcGblEnv { tcg_mod :: Module, -- ^ Module being compiled tcg_semantic_mod :: Module, -- ^ If a signature, the backing module -- See also Note [Identity versus semantic module] tcg_src :: HscSource, -- ^ What kind of module (regular Haskell, hs-boot, hsig) tcg_rdr_env :: GlobalRdrEnv, -- ^ Top level envt; used during renaming tcg_default :: Maybe [Type], -- ^ Types used for defaulting. @Nothing@ => no @default@ decl tcg_fix_env :: FixityEnv, -- ^ Just for things in this module tcg_field_env :: RecFieldEnv, -- ^ Just for things in this module -- See Note [The interactive package] in HscTypes tcg_type_env :: TypeEnv, -- ^ Global type env for the module we are compiling now. All -- TyCons and Classes (for this module) end up in here right away, -- along with their derived constructors, selectors. -- -- (Ids defined in this module start in the local envt, though they -- move to the global envt during zonking) -- -- NB: for what "things in this module" means, see -- Note [The interactive package] in HscTypes tcg_type_env_var :: TcRef TypeEnv, -- Used only to initialise the interface-file -- typechecker in initIfaceTcRn, so that it can see stuff -- bound in this module when dealing with hi-boot recursions -- Updated at intervals (e.g. after dealing with types and classes) tcg_inst_env :: !InstEnv, -- ^ Instance envt for all /home-package/ modules; -- Includes the dfuns in tcg_insts -- NB. BangPattern is to fix a leak, see #15111 tcg_fam_inst_env :: !FamInstEnv, -- ^ Ditto for family instances -- NB. BangPattern is to fix a leak, see #15111 tcg_ann_env :: AnnEnv, -- ^ And for annotations -- Now a bunch of things about this module that are simply -- accumulated, but never consulted until the end. -- Nevertheless, it's convenient to accumulate them along -- with the rest of the info from this module. tcg_exports :: [AvailInfo], -- ^ What is exported tcg_imports :: ImportAvails, -- ^ Information about what was imported from where, including -- things bound in this module. Also store Safe Haskell info -- here about transitive trusted package requirements. -- -- There are not many uses of this field, so you can grep for -- all them. -- -- The ImportAvails records information about the following -- things: -- -- 1. All of the modules you directly imported (tcRnImports) -- 2. The orphans (only!) of all imported modules in a GHCi -- session (runTcInteractive) -- 3. The module that instantiated a signature -- 4. Each of the signatures that merged in -- -- It is used in the following ways: -- - imp_orphs is used to determine what orphan modules should be -- visible in the context (tcVisibleOrphanMods) -- - imp_finsts is used to determine what family instances should -- be visible (tcExtendLocalFamInstEnv) -- - To resolve the meaning of the export list of a module -- (tcRnExports) -- - imp_mods is used to compute usage info (mkIfaceTc, deSugar) -- - imp_trust_own_pkg is used for Safe Haskell in interfaces -- (mkIfaceTc, as well as in HscMain) -- - To create the Dependencies field in interface (mkDependencies) -- These three fields track unused bindings and imports -- See Note [Tracking unused binding and imports] tcg_dus :: DefUses, tcg_used_gres :: TcRef [GlobalRdrElt], tcg_keep :: TcRef NameSet, tcg_th_used :: TcRef Bool, -- ^ @True@ <=> Template Haskell syntax used. -- -- We need this so that we can generate a dependency on the -- Template Haskell package, because the desugarer is going -- to emit loads of references to TH symbols. The reference -- is implicit rather than explicit, so we have to zap a -- mutable variable. tcg_th_splice_used :: TcRef Bool, -- ^ @True@ <=> A Template Haskell splice was used. -- -- Splices disable recompilation avoidance (see #481) tcg_th_top_level_locs :: TcRef (Set RealSrcSpan), -- ^ Locations of the top-level splices; used for providing details on -- scope in error messages for out-of-scope variables tcg_dfun_n :: TcRef OccSet, -- ^ Allows us to choose unique DFun names. tcg_merged :: [(Module, Fingerprint)], -- ^ The requirements we merged with; we always have to recompile -- if any of these changed. -- The next fields accumulate the payload of the module -- The binds, rules and foreign-decl fields are collected -- initially in un-zonked form and are finally zonked in tcRnSrcDecls tcg_rn_exports :: Maybe [(Located (IE GhcRn), Avails)], -- Nothing <=> no explicit export list -- Is always Nothing if we don't want to retain renamed -- exports. -- If present contains each renamed export list item -- together with its exported names. tcg_rn_imports :: [LImportDecl GhcRn], -- Keep the renamed imports regardless. They are not -- voluminous and are needed if you want to report unused imports tcg_rn_decls :: Maybe (HsGroup GhcRn), -- ^ Renamed decls, maybe. @Nothing@ <=> Don't retain renamed -- decls. tcg_dependent_files :: TcRef [FilePath], -- ^ dependencies from addDependentFile tcg_th_topdecls :: TcRef [LHsDecl GhcPs], -- ^ Top-level declarations from addTopDecls tcg_th_foreign_files :: TcRef [(ForeignSrcLang, FilePath)], -- ^ Foreign files emitted from TH. tcg_th_topnames :: TcRef NameSet, -- ^ Exact names bound in top-level declarations in tcg_th_topdecls tcg_th_modfinalizers :: TcRef [(TcLclEnv, ThModFinalizers)], -- ^ Template Haskell module finalizers. -- -- They can use particular local environments. tcg_th_coreplugins :: TcRef [String], -- ^ Core plugins added by Template Haskell code. tcg_th_state :: TcRef (Map TypeRep Dynamic), tcg_th_remote_state :: TcRef (Maybe (ForeignRef (IORef QState))), -- ^ Template Haskell state tcg_ev_binds :: Bag EvBind, -- Top-level evidence bindings -- Things defined in this module, or (in GHCi) -- in the declarations for a single GHCi command. -- For the latter, see Note [The interactive package] in HscTypes tcg_tr_module :: Maybe Id, -- Id for $trModule :: GHC.Types.Module -- for which every module has a top-level defn -- except in GHCi in which case we have Nothing tcg_binds :: LHsBinds GhcTc, -- Value bindings in this module tcg_sigs :: NameSet, -- ...Top-level names that *lack* a signature tcg_imp_specs :: [LTcSpecPrag], -- ...SPECIALISE prags for imported Ids tcg_warns :: Warnings, -- ...Warnings and deprecations tcg_anns :: [Annotation], -- ...Annotations tcg_tcs :: [TyCon], -- ...TyCons and Classes tcg_insts :: [ClsInst], -- ...Instances tcg_fam_insts :: [FamInst], -- ...Family instances tcg_rules :: [LRuleDecl GhcTc], -- ...Rules tcg_fords :: [LForeignDecl GhcTc], -- ...Foreign import & exports tcg_patsyns :: [PatSyn], -- ...Pattern synonyms tcg_doc_hdr :: Maybe LHsDocString, -- ^ Maybe Haddock header docs tcg_hpc :: !AnyHpcUsage, -- ^ @True@ if any part of the -- prog uses hpc instrumentation. -- NB. BangPattern is to fix a leak, see #15111 tcg_self_boot :: SelfBootInfo, -- ^ Whether this module has a -- corresponding hi-boot file tcg_main :: Maybe Name, -- ^ The Name of the main -- function, if this module is -- the main module. tcg_safeInfer :: TcRef (Bool, WarningMessages), -- ^ Has the typechecker inferred this module as -XSafe (Safe Haskell) -- See Note [Safe Haskell Overlapping Instances Implementation], -- although this is used for more than just that failure case. tcg_tc_plugins :: [TcPluginSolver], -- ^ A list of user-defined plugins for the constraint solver. tcg_hf_plugins :: [HoleFitPlugin], -- ^ A list of user-defined plugins for hole fit suggestions. tcg_top_loc :: RealSrcSpan, -- ^ The RealSrcSpan this module came from tcg_static_wc :: TcRef WantedConstraints, -- ^ Wanted constraints of static forms. -- See Note [Constraints in static forms]. tcg_complete_matches :: [CompleteMatch], -- ^ Tracking indices for cost centre annotations tcg_cc_st :: TcRef CostCentreState } -- NB: topModIdentity, not topModSemantic! -- Definition sites of orphan identities will be identity modules, not semantic -- modules. -- Note [Constraints in static forms] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- -- When a static form produces constraints like -- -- f :: StaticPtr (Bool -> String) -- f = static show -- -- we collect them in tcg_static_wc and resolve them at the end -- of type checking. They need to be resolved separately because -- we don't want to resolve them in the context of the enclosing -- expression. Consider -- -- g :: Show a => StaticPtr (a -> String) -- g = static show -- -- If the @Show a0@ constraint that the body of the static form produces was -- resolved in the context of the enclosing expression, then the body of the -- static form wouldn't be closed because the Show dictionary would come from -- g's context instead of coming from the top level. tcVisibleOrphanMods :: TcGblEnv -> ModuleSet tcVisibleOrphanMods tcg_env = mkModuleSet (tcg_mod tcg_env : imp_orphs (tcg_imports tcg_env)) instance ContainsModule TcGblEnv where extractModule env = tcg_semantic_mod env type RecFieldEnv = NameEnv [FieldLabel] -- Maps a constructor name *in this module* -- to the fields for that constructor. -- This is used when dealing with ".." notation in record -- construction and pattern matching. -- The FieldEnv deals *only* with constructors defined in *this* -- module. For imported modules, we get the same info from the -- TypeEnv data SelfBootInfo = NoSelfBoot -- No corresponding hi-boot file | SelfBoot { sb_mds :: ModDetails -- There was a hi-boot file, , sb_tcs :: NameSet } -- defining these TyCons, -- What is sb_tcs used for? See Note [Extra dependencies from .hs-boot files] -- in RnSource {- Note [Tracking unused binding and imports] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We gather three sorts of usage information * tcg_dus :: DefUses (defs/uses) Records what is defined in this module and what is used. Records *defined* Names (local, top-level) and *used* Names (local or imported) Used (a) to report "defined but not used" (see RnNames.reportUnusedNames) (b) to generate version-tracking usage info in interface files (see MkIface.mkUsedNames) This usage info is mainly gathered by the renamer's gathering of free-variables * tcg_used_gres :: TcRef [GlobalRdrElt] Records occurrences of imported entities. Used only to report unused import declarations Records each *occurrence* an *imported* (not locally-defined) entity. The occurrence is recorded by keeping a GlobalRdrElt for it. These is not the GRE that is in the GlobalRdrEnv; rather it is recorded *after* the filtering done by pickGREs. So it reflect /how that occurrence is in scope/. See Note [GRE filtering] in RdrName. * tcg_keep :: TcRef NameSet Records names of the type constructors, data constructors, and Ids that are used by the constraint solver. The typechecker may use find that some imported or locally-defined things are used, even though they do not appear to be mentioned in the source code: (a) The to/from functions for generic data types (b) Top-level variables appearing free in the RHS of an orphan rule (c) Top-level variables appearing free in a TH bracket See Note [Keeping things alive for Template Haskell] in RnSplice (d) The data constructor of a newtype that is used to solve a Coercible instance (e.g. #10347). Example module T10347 (N, mkN) where import Data.Coerce newtype N a = MkN Int mkN :: Int -> N a mkN = coerce Then we wish to record `MkN` as used, since it is (morally) used to perform the coercion in `mkN`. To do so, the Coercible solver updates tcg_keep's TcRef whenever it encounters a use of `coerce` that crosses newtype boundaries. The tcg_keep field is used in two distinct ways: * Desugar.addExportFlagsAndRules. Where things like (a-c) are locally defined, we should give them an an Exported flag, so that the simplifier does not discard them as dead code, and so that they are exposed in the interface file (but not to export to the user). * RnNames.reportUnusedNames. Where newtype data constructors like (d) are imported, we don't want to report them as unused. ************************************************************************ * * The local typechecker environment * * ************************************************************************ Note [The Global-Env/Local-Env story] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ During type checking, we keep in the tcg_type_env * All types and classes * All Ids derived from types and classes (constructors, selectors) At the end of type checking, we zonk the local bindings, and as we do so we add to the tcg_type_env * Locally defined top-level Ids Why? Because they are now Ids not TcIds. This final GlobalEnv is a) fed back (via the knot) to typechecking the unfoldings of interface signatures b) used in the ModDetails of this module -} data TcLclEnv -- Changes as we move inside an expression -- Discarded after typecheck/rename; not passed on to desugarer = TcLclEnv { tcl_loc :: RealSrcSpan, -- Source span tcl_ctxt :: [ErrCtxt], -- Error context, innermost on top tcl_tclvl :: TcLevel, -- Birthplace for new unification variables tcl_th_ctxt :: ThStage, -- Template Haskell context tcl_th_bndrs :: ThBindEnv, -- and binder info -- The ThBindEnv records the TH binding level of in-scope Names -- defined in this module (not imported) -- We can't put this info in the TypeEnv because it's needed -- (and extended) in the renamer, for untyed splices tcl_arrow_ctxt :: ArrowCtxt, -- Arrow-notation context tcl_rdr :: LocalRdrEnv, -- Local name envt -- Maintained during renaming, of course, but also during -- type checking, solely so that when renaming a Template-Haskell -- splice we have the right environment for the renamer. -- -- Does *not* include global name envt; may shadow it -- Includes both ordinary variables and type variables; -- they are kept distinct because tyvar have a different -- occurrence constructor (Name.TvOcc) -- We still need the unsullied global name env so that -- we can look up record field names tcl_env :: TcTypeEnv, -- The local type environment: -- Ids and TyVars defined in this module tcl_bndrs :: TcBinderStack, -- Used for reporting relevant bindings, -- and for tidying types tcl_lie :: TcRef WantedConstraints, -- Place to accumulate type constraints tcl_errs :: TcRef Messages -- Place to accumulate errors } setLclEnvTcLevel :: TcLclEnv -> TcLevel -> TcLclEnv setLclEnvTcLevel env lvl = env { tcl_tclvl = lvl } getLclEnvTcLevel :: TcLclEnv -> TcLevel getLclEnvTcLevel = tcl_tclvl setLclEnvLoc :: TcLclEnv -> RealSrcSpan -> TcLclEnv setLclEnvLoc env loc = env { tcl_loc = loc } getLclEnvLoc :: TcLclEnv -> RealSrcSpan getLclEnvLoc = tcl_loc type ErrCtxt = (Bool, TidyEnv -> TcM (TidyEnv, MsgDoc)) -- Monadic so that we have a chance -- to deal with bound type variables just before error -- message construction -- Bool: True <=> this is a landmark context; do not -- discard it when trimming for display -- These are here to avoid module loops: one might expect them -- in Constraint, but they refer to ErrCtxt which refers to TcM. -- Easier to just keep these definitions here, alongside TcM. pushErrCtxt :: CtOrigin -> ErrCtxt -> CtLoc -> CtLoc pushErrCtxt o err loc@(CtLoc { ctl_env = lcl }) = loc { ctl_origin = o, ctl_env = lcl { tcl_ctxt = err : tcl_ctxt lcl } } pushErrCtxtSameOrigin :: ErrCtxt -> CtLoc -> CtLoc -- Just add information w/o updating the origin! pushErrCtxtSameOrigin err loc@(CtLoc { ctl_env = lcl }) = loc { ctl_env = lcl { tcl_ctxt = err : tcl_ctxt lcl } } type TcTypeEnv = NameEnv TcTyThing type ThBindEnv = NameEnv (TopLevelFlag, ThLevel) -- Domain = all Ids bound in this module (ie not imported) -- The TopLevelFlag tells if the binding is syntactically top level. -- We need to know this, because the cross-stage persistence story allows -- cross-stage at arbitrary types if the Id is bound at top level. -- -- Nota bene: a ThLevel of 'outerLevel' is *not* the same as being -- bound at top level! See Note [Template Haskell levels] in TcSplice {- Note [Given Insts] ~~~~~~~~~~~~~~~~~~ Because of GADTs, we have to pass inwards the Insts provided by type signatures and existential contexts. Consider data T a where { T1 :: b -> b -> T [b] } f :: Eq a => T a -> Bool f (T1 x y) = [x]==[y] The constructor T1 binds an existential variable 'b', and we need Eq [b]. Well, we have it, because Eq a refines to Eq [b], but we can only spot that if we pass it inwards. -} -- | Type alias for 'IORef'; the convention is we'll use this for mutable -- bits of data in 'TcGblEnv' which are updated during typechecking and -- returned at the end. type TcRef a = IORef a -- ToDo: when should I refer to it as a 'TcId' instead of an 'Id'? type TcId = Id type TcIdSet = IdSet --------------------------- -- The TcBinderStack --------------------------- type TcBinderStack = [TcBinder] -- This is a stack of locally-bound ids and tyvars, -- innermost on top -- Used only in error reporting (relevantBindings in TcError), -- and in tidying -- We can't use the tcl_env type environment, because it doesn't -- keep track of the nesting order data TcBinder = TcIdBndr TcId TopLevelFlag -- Tells whether the binding is syntactically top-level -- (The monomorphic Ids for a recursive group count -- as not-top-level for this purpose.) | TcIdBndr_ExpType -- Variant that allows the type to be specified as -- an ExpType Name ExpType TopLevelFlag | TcTvBndr -- e.g. case x of P (y::a) -> blah Name -- We bind the lexical name "a" to the type of y, TyVar -- which might be an utterly different (perhaps -- existential) tyvar instance Outputable TcBinder where ppr (TcIdBndr id top_lvl) = ppr id <> brackets (ppr top_lvl) ppr (TcIdBndr_ExpType id _ top_lvl) = ppr id <> brackets (ppr top_lvl) ppr (TcTvBndr name tv) = ppr name <+> ppr tv instance HasOccName TcBinder where occName (TcIdBndr id _) = occName (idName id) occName (TcIdBndr_ExpType name _ _) = occName name occName (TcTvBndr name _) = occName name -- fixes #12177 -- Builds up a list of bindings whose OccName has not been seen before -- i.e., If ys = removeBindingShadowing xs -- then -- - ys is obtained from xs by deleting some elements -- - ys has no duplicate OccNames -- - The first duplicated OccName in xs is retained in ys -- Overloaded so that it can be used for both GlobalRdrElt in typed-hole -- substitutions and TcBinder when looking for relevant bindings. removeBindingShadowing :: HasOccName a => [a] -> [a] removeBindingShadowing bindings = reverse $ fst $ foldl (\(bindingAcc, seenNames) binding -> if occName binding `elemOccSet` seenNames -- if we've seen it then (bindingAcc, seenNames) -- skip it else (binding:bindingAcc, extendOccSet seenNames (occName binding))) ([], emptyOccSet) bindings --------------------------- -- Template Haskell stages and levels --------------------------- data SpliceType = Typed | Untyped data ThStage -- See Note [Template Haskell state diagram] in TcSplice = Splice SpliceType -- Inside a top-level splice -- This code will be run *at compile time*; -- the result replaces the splice -- Binding level = 0 | RunSplice (TcRef [ForeignRef (TH.Q ())]) -- Set when running a splice, i.e. NOT when renaming or typechecking the -- Haskell code for the splice. See Note [RunSplice ThLevel]. -- -- Contains a list of mod finalizers collected while executing the splice. -- -- 'addModFinalizer' inserts finalizers here, and from here they are taken -- to construct an @HsSpliced@ annotation for untyped splices. See Note -- [Delaying modFinalizers in untyped splices] in "RnSplice". -- -- For typed splices, the typechecker takes finalizers from here and -- inserts them in the list of finalizers in the global environment. -- -- See Note [Collecting modFinalizers in typed splices] in "TcSplice". | Comp -- Ordinary Haskell code -- Binding level = 1 | Brack -- Inside brackets ThStage -- Enclosing stage PendingStuff data PendingStuff = RnPendingUntyped -- Renaming the inside of an *untyped* bracket (TcRef [PendingRnSplice]) -- Pending splices in here | RnPendingTyped -- Renaming the inside of a *typed* bracket | TcPending -- Typechecking the inside of a typed bracket (TcRef [PendingTcSplice]) -- Accumulate pending splices here (TcRef WantedConstraints) -- and type constraints here topStage, topAnnStage, topSpliceStage :: ThStage topStage = Comp topAnnStage = Splice Untyped topSpliceStage = Splice Untyped instance Outputable ThStage where ppr (Splice _) = text "Splice" ppr (RunSplice _) = text "RunSplice" ppr Comp = text "Comp" ppr (Brack s _) = text "Brack" <> parens (ppr s) type ThLevel = Int -- NB: see Note [Template Haskell levels] in TcSplice -- Incremented when going inside a bracket, -- decremented when going inside a splice -- NB: ThLevel is one greater than the 'n' in Fig 2 of the -- original "Template meta-programming for Haskell" paper impLevel, outerLevel :: ThLevel impLevel = 0 -- Imported things; they can be used inside a top level splice outerLevel = 1 -- Things defined outside brackets thLevel :: ThStage -> ThLevel thLevel (Splice _) = 0 thLevel (RunSplice _) = -- See Note [RunSplice ThLevel]. panic "thLevel: called when running a splice" thLevel Comp = 1 thLevel (Brack s _) = thLevel s + 1 {- Node [RunSplice ThLevel] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The 'RunSplice' stage is set when executing a splice, and only when running a splice. In particular it is not set when the splice is renamed or typechecked. 'RunSplice' is needed to provide a reference where 'addModFinalizer' can insert the finalizer (see Note [Delaying modFinalizers in untyped splices]), and 'addModFinalizer' runs when doing Q things. Therefore, It doesn't make sense to set 'RunSplice' when renaming or typechecking the splice, where 'Splice', 'Brack' or 'Comp' are used instead. -} --------------------------- -- Arrow-notation context --------------------------- {- Note [Escaping the arrow scope] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In arrow notation, a variable bound by a proc (or enclosed let/kappa) is not in scope to the left of an arrow tail (-<) or the head of (|..|). For example proc x -> (e1 -< e2) Here, x is not in scope in e1, but it is in scope in e2. This can get a bit complicated: let x = 3 in proc y -> (proc z -> e1) -< e2 Here, x and z are in scope in e1, but y is not. We implement this by recording the environment when passing a proc (using newArrowScope), and returning to that (using escapeArrowScope) on the left of -< and the head of (|..|). All this can be dealt with by the *renamer*. But the type checker needs to be involved too. Example (arrowfail001) class Foo a where foo :: a -> () data Bar = forall a. Foo a => Bar a get :: Bar -> () get = proc x -> case x of Bar a -> foo -< a Here the call of 'foo' gives rise to a (Foo a) constraint that should not be captured by the pattern match on 'Bar'. Rather it should join the constraints from further out. So we must capture the constraint bag from further out in the ArrowCtxt that we push inwards. -} data ArrowCtxt -- Note [Escaping the arrow scope] = NoArrowCtxt | ArrowCtxt LocalRdrEnv (TcRef WantedConstraints) --------------------------- -- TcTyThing --------------------------- -- | A typecheckable thing available in a local context. Could be -- 'AGlobal' 'TyThing', but also lexically scoped variables, etc. -- See 'TcEnv' for how to retrieve a 'TyThing' given a 'Name'. data TcTyThing = AGlobal TyThing -- Used only in the return type of a lookup | ATcId -- Ids defined in this module; may not be fully zonked { tct_id :: TcId , tct_info :: IdBindingInfo -- See Note [Meaning of IdBindingInfo] } | ATyVar Name TcTyVar -- See Note [Type variables in the type environment] | ATcTyCon TyCon -- Used temporarily, during kind checking, for the -- tycons and clases in this recursive group -- The TyCon is always a TcTyCon. Its kind -- can be a mono-kind or a poly-kind; in TcTyClsDcls see -- Note [Type checking recursive type and class declarations] | APromotionErr PromotionErr data PromotionErr = TyConPE -- TyCon used in a kind before we are ready -- data T :: T -> * where ... | ClassPE -- Ditto Class | FamDataConPE -- Data constructor for a data family -- See Note [AFamDataCon: not promoting data family constructors] -- in TcEnv. | ConstrainedDataConPE PredType -- Data constructor with a non-equality context -- See Note [Don't promote data constructors with -- non-equality contexts] in TcHsType | PatSynPE -- Pattern synonyms -- See Note [Don't promote pattern synonyms] in TcEnv | RecDataConPE -- Data constructor in a recursive loop -- See Note [Recursion and promoting data constructors] in TcTyClsDecls | NoDataKindsTC -- -XDataKinds not enabled (for a tycon) | NoDataKindsDC -- -XDataKinds not enabled (for a datacon) instance Outputable TcTyThing where -- Debugging only ppr (AGlobal g) = ppr g ppr elt@(ATcId {}) = text "Identifier" <> brackets (ppr (tct_id elt) <> dcolon <> ppr (varType (tct_id elt)) <> comma <+> ppr (tct_info elt)) ppr (ATyVar n tv) = text "Type variable" <+> quotes (ppr n) <+> equals <+> ppr tv <+> dcolon <+> ppr (varType tv) ppr (ATcTyCon tc) = text "ATcTyCon" <+> ppr tc <+> dcolon <+> ppr (tyConKind tc) ppr (APromotionErr err) = text "APromotionErr" <+> ppr err -- | IdBindingInfo describes how an Id is bound. -- -- It is used for the following purposes: -- a) for static forms in TcExpr.checkClosedInStaticForm and -- b) to figure out when a nested binding can be generalised, -- in TcBinds.decideGeneralisationPlan. -- data IdBindingInfo -- See Note [Meaning of IdBindingInfo and ClosedTypeId] = NotLetBound | ClosedLet | NonClosedLet RhsNames -- Used for (static e) checks only ClosedTypeId -- Used for generalisation checks -- and for (static e) checks -- | IsGroupClosed describes a group of mutually-recursive bindings data IsGroupClosed = IsGroupClosed (NameEnv RhsNames) -- Free var info for the RHS of each binding in the goup -- Used only for (static e) checks ClosedTypeId -- True <=> all the free vars of the group are -- imported or ClosedLet or -- NonClosedLet with ClosedTypeId=True. -- In particular, no tyvars, no NotLetBound type RhsNames = NameSet -- Names of variables, mentioned on the RHS of -- a definition, that are not Global or ClosedLet type ClosedTypeId = Bool -- See Note [Meaning of IdBindingInfo and ClosedTypeId] {- Note [Meaning of IdBindingInfo] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ NotLetBound means that the Id is not let-bound (e.g. it is bound in a lambda-abstraction or in a case pattern) ClosedLet means that - The Id is let-bound, - Any free term variables are also Global or ClosedLet - Its type has no free variables (NB: a top-level binding subject to the MR might have free vars in its type) These ClosedLets can definitely be floated to top level; and we may need to do so for static forms. Property: ClosedLet is equivalent to NonClosedLet emptyNameSet True (NonClosedLet (fvs::RhsNames) (cl::ClosedTypeId)) means that - The Id is let-bound - The fvs::RhsNames contains the free names of the RHS, excluding Global and ClosedLet ones. - For the ClosedTypeId field see Note [Bindings with closed types] For (static e) to be valid, we need for every 'x' free in 'e', that x's binding is floatable to the top level. Specifically: * x's RhsNames must be empty * x's type has no free variables See Note [Grand plan for static forms] in StaticPtrTable.hs. This test is made in TcExpr.checkClosedInStaticForm. Actually knowing x's RhsNames (rather than just its emptiness or otherwise) is just so we can produce better error messages Note [Bindings with closed types: ClosedTypeId] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider f x = let g ys = map not ys in ... Can we generalise 'g' under the OutsideIn algorithm? Yes, because all g's free variables are top-level; that is they themselves have no free type variables, and it is the type variables in the environment that makes things tricky for OutsideIn generalisation. Here's the invariant: If an Id has ClosedTypeId=True (in its IdBindingInfo), then the Id's type is /definitely/ closed (has no free type variables). Specifically, a) The Id's acutal type is closed (has no free tyvars) b) Either the Id has a (closed) user-supplied type signature or all its free variables are Global/ClosedLet or NonClosedLet with ClosedTypeId=True. In particular, none are NotLetBound. Why is (b) needed? Consider \x. (x :: Int, let y = x+1 in ...) Initially x::alpha. If we happen to typecheck the 'let' before the (x::Int), y's type will have a free tyvar; but if the other way round it won't. So we treat any let-bound variable with a free non-let-bound variable as not ClosedTypeId, regardless of what the free vars of its type actually are. But if it has a signature, all is well: \x. ...(let { y::Int; y = x+1 } in let { v = y+2 } in ...)... Here the signature on 'v' makes 'y' a ClosedTypeId, so we can generalise 'v'. Note that: * A top-level binding may not have ClosedTypeId=True, if it suffers from the MR * A nested binding may be closed (eg 'g' in the example we started with). Indeed, that's the point; whether a function is defined at top level or nested is orthogonal to the question of whether or not it is closed. * A binding may be non-closed because it mentions a lexically scoped *type variable* Eg f :: forall a. blah f x = let g y = ...(y::a)... Under OutsideIn we are free to generalise an Id all of whose free variables have ClosedTypeId=True (or imported). This is an extension compared to the JFP paper on OutsideIn, which used "top-level" as a proxy for "closed". (It's not a good proxy anyway -- the MR can make a top-level binding with a free type variable.) Note [Type variables in the type environment] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The type environment has a binding for each lexically-scoped type variable that is in scope. For example f :: forall a. a -> a f x = (x :: a) g1 :: [a] -> a g1 (ys :: [b]) = head ys :: b g2 :: [Int] -> Int g2 (ys :: [c]) = head ys :: c * The forall'd variable 'a' in the signature scopes over f's RHS. * The pattern-bound type variable 'b' in 'g1' scopes over g1's RHS; note that it is bound to a skolem 'a' which is not itself lexically in scope. * The pattern-bound type variable 'c' in 'g2' is bound to Int; that is, pattern-bound type variables can stand for arbitrary types. (see GHC proposal #128 "Allow ScopedTypeVariables to refer to types" https://github.com/ghc-proposals/ghc-proposals/pull/128, and the paper "Type variables in patterns", Haskell Symposium 2018. This is implemented by the constructor ATyVar Name TcTyVar in the type environment. * The Name is the name of the original, lexically scoped type variable * The TcTyVar is sometimes a skolem (like in 'f'), and sometimes a unification variable (like in 'g1', 'g2'). We never zonk the type environment so in the latter case it always stays as a unification variable, although that variable may be later unified with a type (such as Int in 'g2'). -} instance Outputable IdBindingInfo where ppr NotLetBound = text "NotLetBound" ppr ClosedLet = text "TopLevelLet" ppr (NonClosedLet fvs closed_type) = text "TopLevelLet" <+> ppr fvs <+> ppr closed_type instance Outputable PromotionErr where ppr ClassPE = text "ClassPE" ppr TyConPE = text "TyConPE" ppr PatSynPE = text "PatSynPE" ppr FamDataConPE = text "FamDataConPE" ppr (ConstrainedDataConPE pred) = text "ConstrainedDataConPE" <+> parens (ppr pred) ppr RecDataConPE = text "RecDataConPE" ppr NoDataKindsTC = text "NoDataKindsTC" ppr NoDataKindsDC = text "NoDataKindsDC" pprTcTyThingCategory :: TcTyThing -> SDoc pprTcTyThingCategory (AGlobal thing) = pprTyThingCategory thing pprTcTyThingCategory (ATyVar {}) = text "Type variable" pprTcTyThingCategory (ATcId {}) = text "Local identifier" pprTcTyThingCategory (ATcTyCon {}) = text "Local tycon" pprTcTyThingCategory (APromotionErr pe) = pprPECategory pe pprPECategory :: PromotionErr -> SDoc pprPECategory ClassPE = text "Class" pprPECategory TyConPE = text "Type constructor" pprPECategory PatSynPE = text "Pattern synonym" pprPECategory FamDataConPE = text "Data constructor" pprPECategory ConstrainedDataConPE{} = text "Data constructor" pprPECategory RecDataConPE = text "Data constructor" pprPECategory NoDataKindsTC = text "Type constructor" pprPECategory NoDataKindsDC = text "Data constructor" {- ************************************************************************ * * Operations over ImportAvails * * ************************************************************************ -} -- | 'ImportAvails' summarises what was imported from where, irrespective of -- whether the imported things are actually used or not. It is used: -- -- * when processing the export list, -- -- * when constructing usage info for the interface file, -- -- * to identify the list of directly imported modules for initialisation -- purposes and for optimised overlap checking of family instances, -- -- * when figuring out what things are really unused -- data ImportAvails = ImportAvails { imp_mods :: ImportedMods, -- = ModuleEnv [ImportedModsVal], -- ^ Domain is all directly-imported modules -- -- See the documentation on ImportedModsVal in HscTypes for the -- meaning of the fields. -- -- We need a full ModuleEnv rather than a ModuleNameEnv here, -- because we might be importing modules of the same name from -- different packages. (currently not the case, but might be in the -- future). imp_dep_mods :: ModuleNameEnv (ModuleName, IsBootInterface), -- ^ Home-package modules needed by the module being compiled -- -- It doesn't matter whether any of these dependencies -- are actually /used/ when compiling the module; they -- are listed if they are below it at all. For -- example, suppose M imports A which imports X. Then -- compiling M might not need to consult X.hi, but X -- is still listed in M's dependencies. imp_dep_pkgs :: Set InstalledUnitId, -- ^ Packages needed by the module being compiled, whether directly, -- or via other modules in this package, or via modules imported -- from other packages. imp_trust_pkgs :: Set InstalledUnitId, -- ^ This is strictly a subset of imp_dep_pkgs and records the -- packages the current module needs to trust for Safe Haskell -- compilation to succeed. A package is required to be trusted if -- we are dependent on a trustworthy module in that package. -- While perhaps making imp_dep_pkgs a tuple of (UnitId, Bool) -- where True for the bool indicates the package is required to be -- trusted is the more logical design, doing so complicates a lot -- of code not concerned with Safe Haskell. -- See Note [RnNames . Tracking Trust Transitively] imp_trust_own_pkg :: Bool, -- ^ Do we require that our own package is trusted? -- This is to handle efficiently the case where a Safe module imports -- a Trustworthy module that resides in the same package as it. -- See Note [RnNames . Trust Own Package] imp_orphs :: [Module], -- ^ Orphan modules below us in the import tree (and maybe including -- us for imported modules) imp_finsts :: [Module] -- ^ Family instance modules below us in the import tree (and maybe -- including us for imported modules) } mkModDeps :: [(ModuleName, IsBootInterface)] -> ModuleNameEnv (ModuleName, IsBootInterface) mkModDeps deps = foldl' add emptyUFM deps where add env elt@(m,_) = addToUFM env m elt modDepsElts :: ModuleNameEnv (ModuleName, IsBootInterface) -> [(ModuleName, IsBootInterface)] modDepsElts = sort . nonDetEltsUFM -- It's OK to use nonDetEltsUFM here because sorting by module names -- restores determinism emptyImportAvails :: ImportAvails emptyImportAvails = ImportAvails { imp_mods = emptyModuleEnv, imp_dep_mods = emptyUFM, imp_dep_pkgs = S.empty, imp_trust_pkgs = S.empty, imp_trust_own_pkg = False, imp_orphs = [], imp_finsts = [] } -- | Union two ImportAvails -- -- This function is a key part of Import handling, basically -- for each import we create a separate ImportAvails structure -- and then union them all together with this function. plusImportAvails :: ImportAvails -> ImportAvails -> ImportAvails plusImportAvails (ImportAvails { imp_mods = mods1, imp_dep_mods = dmods1, imp_dep_pkgs = dpkgs1, imp_trust_pkgs = tpkgs1, imp_trust_own_pkg = tself1, imp_orphs = orphs1, imp_finsts = finsts1 }) (ImportAvails { imp_mods = mods2, imp_dep_mods = dmods2, imp_dep_pkgs = dpkgs2, imp_trust_pkgs = tpkgs2, imp_trust_own_pkg = tself2, imp_orphs = orphs2, imp_finsts = finsts2 }) = ImportAvails { imp_mods = plusModuleEnv_C (++) mods1 mods2, imp_dep_mods = plusUFM_C plus_mod_dep dmods1 dmods2, imp_dep_pkgs = dpkgs1 `S.union` dpkgs2, imp_trust_pkgs = tpkgs1 `S.union` tpkgs2, imp_trust_own_pkg = tself1 || tself2, imp_orphs = orphs1 `unionLists` orphs2, imp_finsts = finsts1 `unionLists` finsts2 } where plus_mod_dep r1@(m1, boot1) r2@(m2, boot2) | ASSERT2( m1 == m2, (ppr m1 <+> ppr m2) $$ (ppr boot1 <+> ppr boot2) ) boot1 = r2 | otherwise = r1 -- If either side can "see" a non-hi-boot interface, use that -- Reusing existing tuples saves 10% of allocations on test -- perf/compiler/MultiLayerModules {- ************************************************************************ * * \subsection{Where from} * * ************************************************************************ The @WhereFrom@ type controls where the renamer looks for an interface file -} data WhereFrom = ImportByUser IsBootInterface -- Ordinary user import (perhaps {-# SOURCE #-}) | ImportBySystem -- Non user import. | ImportByPlugin -- Importing a plugin; -- See Note [Care with plugin imports] in LoadIface instance Outputable WhereFrom where ppr (ImportByUser is_boot) | is_boot = text "{- SOURCE -}" | otherwise = empty ppr ImportBySystem = text "{- SYSTEM -}" ppr ImportByPlugin = text "{- PLUGIN -}" {- ********************************************************************* * * Type signatures * * ********************************************************************* -} -- These data types need to be here only because -- TcSimplify uses them, and TcSimplify is fairly -- low down in the module hierarchy type TcSigFun = Name -> Maybe TcSigInfo data TcSigInfo = TcIdSig TcIdSigInfo | TcPatSynSig TcPatSynInfo data TcIdSigInfo -- See Note [Complete and partial type signatures] = CompleteSig -- A complete signature with no wildcards, -- so the complete polymorphic type is known. { sig_bndr :: TcId -- The polymorphic Id with that type , sig_ctxt :: UserTypeCtxt -- In the case of type-class default methods, -- the Name in the FunSigCtxt is not the same -- as the TcId; the former is 'op', while the -- latter is '$dmop' or some such , sig_loc :: SrcSpan -- Location of the type signature } | PartialSig -- A partial type signature (i.e. includes one or more -- wildcards). In this case it doesn't make sense to give -- the polymorphic Id, because we are going to /infer/ its -- type, so we can't make the polymorphic Id ab-initio { psig_name :: Name -- Name of the function; used when report wildcards , psig_hs_ty :: LHsSigWcType GhcRn -- The original partial signature in -- HsSyn form , sig_ctxt :: UserTypeCtxt , sig_loc :: SrcSpan -- Location of the type signature } {- Note [Complete and partial type signatures] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ A type signature is partial when it contains one or more wildcards (= type holes). The wildcard can either be: * A (type) wildcard occurring in sig_theta or sig_tau. These are stored in sig_wcs. f :: Bool -> _ g :: Eq _a => _a -> _a -> Bool * Or an extra-constraints wildcard, stored in sig_cts: h :: (Num a, _) => a -> a A type signature is a complete type signature when there are no wildcards in the type signature, i.e. iff sig_wcs is empty and sig_extra_cts is Nothing. -} data TcIdSigInst = TISI { sig_inst_sig :: TcIdSigInfo , sig_inst_skols :: [(Name, TcTyVar)] -- Instantiated type and kind variables, TyVarTvs -- The Name is the Name that the renamer chose; -- but the TcTyVar may come from instantiating -- the type and hence have a different unique. -- No need to keep track of whether they are truly lexically -- scoped because the renamer has named them uniquely -- See Note [Binding scoped type variables] in TcSigs -- -- NB: The order of sig_inst_skols is irrelevant -- for a CompleteSig, but for a PartialSig see -- Note [Quantified varaibles in partial type signatures] , sig_inst_theta :: TcThetaType -- Instantiated theta. In the case of a -- PartialSig, sig_theta does not include -- the extra-constraints wildcard , sig_inst_tau :: TcSigmaType -- Instantiated tau -- See Note [sig_inst_tau may be polymorphic] -- Relevant for partial signature only , sig_inst_wcs :: [(Name, TcTyVar)] -- Like sig_inst_skols, but for /named/ wildcards (_a etc). -- The named wildcards scope over the binding, and hence -- their Names may appear in type signatures in the binding , sig_inst_wcx :: Maybe TcType -- Extra-constraints wildcard to fill in, if any -- If this exists, it is surely of the form (meta_tv |> co) -- (where the co might be reflexive). This is filled in -- only from the return value of TcHsType.tcAnonWildCardOcc } {- Note [sig_inst_tau may be polymorphic] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Note that "sig_inst_tau" might actually be a polymorphic type, if the original function had a signature like forall a. Eq a => forall b. Ord b => .... But that's ok: tcMatchesFun (called by tcRhs) can deal with that It happens, too! See Note [Polymorphic methods] in TcClassDcl. Note [Quantified varaibles in partial type signatures] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Consider f :: forall a b. _ -> a -> _ -> b f (x,y) p q = q Then we expect f's final type to be f :: forall {x,y}. forall a b. (x,y) -> a -> b -> b Note that x,y are Inferred, and can't be use for visible type application (VTA). But a,b are Specified, and remain Specified in the final type, so we can use VTA for them. (Exception: if it turns out that a's kind mentions b we need to reorder them with scopedSort.) The sig_inst_skols of the TISI from a partial signature records that original order, and is used to get the variables of f's final type in the correct order. Note [Wildcards in partial signatures] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The wildcards in psig_wcs may stand for a type mentioning the universally-quantified tyvars of psig_ty E.g. f :: forall a. _ -> a f x = x We get sig_inst_skols = [a] sig_inst_tau = _22 -> a sig_inst_wcs = [_22] and _22 in the end is unified with the type 'a' Moreover the kind of a wildcard in sig_inst_wcs may mention the universally-quantified tyvars sig_inst_skols e.g. f :: t a -> t _ Here we get sig_inst_skols = [k:*, (t::k ->*), (a::k)] sig_inst_tau = t a -> t _22 sig_inst_wcs = [ _22::k ] -} data TcPatSynInfo = TPSI { patsig_name :: Name, patsig_implicit_bndrs :: [TyVarBinder], -- Implicitly-bound kind vars (Inferred) and -- implicitly-bound type vars (Specified) -- See Note [The pattern-synonym signature splitting rule] in TcPatSyn patsig_univ_bndrs :: [TyVar], -- Bound by explicit user forall patsig_req :: TcThetaType, patsig_ex_bndrs :: [TyVar], -- Bound by explicit user forall patsig_prov :: TcThetaType, patsig_body_ty :: TcSigmaType } instance Outputable TcSigInfo where ppr (TcIdSig idsi) = ppr idsi ppr (TcPatSynSig tpsi) = text "TcPatSynInfo" <+> ppr tpsi instance Outputable TcIdSigInfo where ppr (CompleteSig { sig_bndr = bndr }) = ppr bndr <+> dcolon <+> ppr (idType bndr) ppr (PartialSig { psig_name = name, psig_hs_ty = hs_ty }) = text "psig" <+> ppr name <+> dcolon <+> ppr hs_ty instance Outputable TcIdSigInst where ppr (TISI { sig_inst_sig = sig, sig_inst_skols = skols , sig_inst_theta = theta, sig_inst_tau = tau }) = hang (ppr sig) 2 (vcat [ ppr skols, ppr theta <+> darrow <+> ppr tau ]) instance Outputable TcPatSynInfo where ppr (TPSI{ patsig_name = name}) = ppr name isPartialSig :: TcIdSigInst -> Bool isPartialSig (TISI { sig_inst_sig = PartialSig {} }) = True isPartialSig _ = False -- | No signature or a partial signature hasCompleteSig :: TcSigFun -> Name -> Bool hasCompleteSig sig_fn name = case sig_fn name of Just (TcIdSig (CompleteSig {})) -> True _ -> False {- Constraint Solver Plugins ------------------------- -} type TcPluginSolver = [Ct] -- given -> [Ct] -- derived -> [Ct] -- wanted -> TcPluginM TcPluginResult newtype TcPluginM a = TcPluginM (EvBindsVar -> TcM a) deriving (Functor) instance Applicative TcPluginM where pure x = TcPluginM (const $ pure x) (<*>) = ap instance Monad TcPluginM where #if !MIN_VERSION_base(4,13,0) fail = MonadFail.fail #endif TcPluginM m >>= k = TcPluginM (\ ev -> do a <- m ev runTcPluginM (k a) ev) instance MonadFail.MonadFail TcPluginM where fail x = TcPluginM (const $ fail x) runTcPluginM :: TcPluginM a -> EvBindsVar -> TcM a runTcPluginM (TcPluginM m) = m -- | This function provides an escape for direct access to -- the 'TcM` monad. It should not be used lightly, and -- the provided 'TcPluginM' API should be favoured instead. unsafeTcPluginTcM :: TcM a -> TcPluginM a unsafeTcPluginTcM = TcPluginM . const -- | Access the 'EvBindsVar' carried by the 'TcPluginM' during -- constraint solving. Returns 'Nothing' if invoked during -- 'tcPluginInit' or 'tcPluginStop'. getEvBindsTcPluginM :: TcPluginM EvBindsVar getEvBindsTcPluginM = TcPluginM return data TcPlugin = forall s. TcPlugin { tcPluginInit :: TcPluginM s -- ^ Initialize plugin, when entering type-checker. , tcPluginSolve :: s -> TcPluginSolver -- ^ Solve some constraints. -- TODO: WRITE MORE DETAILS ON HOW THIS WORKS. , tcPluginStop :: s -> TcPluginM () -- ^ Clean up after the plugin, when exiting the type-checker. } data TcPluginResult = TcPluginContradiction [Ct] -- ^ The plugin found a contradiction. -- The returned constraints are removed from the inert set, -- and recorded as insoluble. | TcPluginOk [(EvTerm,Ct)] [Ct] -- ^ The first field is for constraints that were solved. -- These are removed from the inert set, -- and the evidence for them is recorded. -- The second field contains new work, that should be processed by -- the constraint solver. {- ********************************************************************* * * Role annotations * * ********************************************************************* -} type RoleAnnotEnv = NameEnv (LRoleAnnotDecl GhcRn) mkRoleAnnotEnv :: [LRoleAnnotDecl GhcRn] -> RoleAnnotEnv mkRoleAnnotEnv role_annot_decls = mkNameEnv [ (name, ra_decl) | ra_decl <- role_annot_decls , let name = roleAnnotDeclName (unLoc ra_decl) , not (isUnboundName name) ] -- Some of the role annots will be unbound; -- we don't wish to include these emptyRoleAnnotEnv :: RoleAnnotEnv emptyRoleAnnotEnv = emptyNameEnv lookupRoleAnnot :: RoleAnnotEnv -> Name -> Maybe (LRoleAnnotDecl GhcRn) lookupRoleAnnot = lookupNameEnv getRoleAnnots :: [Name] -> RoleAnnotEnv -> [LRoleAnnotDecl GhcRn] getRoleAnnots bndrs role_env = mapMaybe (lookupRoleAnnot role_env) bndrs