{-# LANGUAGE LambdaCase #-} {-# LANGUAGE PatternSynonyms #-} {- This module contains helper functions for reporting and creating unbound variables. -} module GHC.Rename.Unbound ( mkUnboundName , mkUnboundNameRdr , mkUnboundGRE , mkUnboundGRERdr , isUnboundName , reportUnboundName , unknownNameSuggestions , unknownNameSuggestionsMessage , similarNameSuggestions , fieldSelectorSuggestions , WhatLooking(..) , WhereLooking(..) , LookingFor(..) , unboundName , unboundNameX , unboundTermNameInTypes , IsTermInTypes(..) , notInScopeErr , relevantNameSpace , suggestionIsRelevant , termNameInType ) where import GHC.Prelude import GHC.Driver.DynFlags import GHC.Driver.Ppr import GHC.Driver.Env (hsc_units) import GHC.Driver.Env.Types import {-# SOURCE #-} GHC.Tc.Errors.Hole ( getHoleFitDispConfig ) import GHC.Tc.Errors.Types import GHC.Tc.Utils.Monad import GHC.Builtin.Names ( mkUnboundName, isUnboundName ) import GHC.Utils.Misc import GHC.Utils.Panic (panic) import GHC.Data.Maybe import GHC.Data.FastString import qualified GHC.LanguageExtensions as LangExt import GHC.Types.Hint ( GhcHint (SuggestExtension, RemindFieldSelectorSuppressed, ImportSuggestion, SuggestSimilarNames) , LanguageExtensionHint (SuggestSingleExtension) , ImportSuggestion(..), SimilarName(..), HowInScope(..) ) import GHC.Types.SrcLoc as SrcLoc import GHC.Types.Name import GHC.Types.Name.Reader import GHC.Unit.Module import GHC.Unit.Module.Imported import GHC.Utils.Outputable import GHC.Runtime.Context import GHC.Data.Bag import Language.Haskell.Syntax.ImpExp import Data.List (sortBy, partition) import Data.List.NonEmpty ( pattern (:|), NonEmpty ) import qualified Data.List.NonEmpty as NE ( nonEmpty ) import Data.Function ( on ) import qualified Data.Semigroup as S import qualified Data.Map as M {- ************************************************************************ * * What to do when a lookup fails * * ************************************************************************ -} data WhereLooking = WL_Anywhere -- Any binding | WL_Global -- Any top-level binding (local or imported) | WL_LocalTop -- Any top-level binding in this module | WL_LocalOnly -- Only local bindings -- (pattern synonyms declarations, -- see Note [Renaming pattern synonym variables] -- in GHC.Rename.Bind) data LookingFor = LF { lf_which :: WhatLooking , lf_where :: WhereLooking } data IsTermInTypes = UnknownTermInTypes RdrName | TermInTypes RdrName | NoTermInTypes mkUnboundNameRdr :: RdrName -> Name mkUnboundNameRdr rdr = mkUnboundName (rdrNameOcc rdr) mkUnboundGRE :: OccName -> GlobalRdrElt mkUnboundGRE occ = mkLocalGRE UnboundGRE NoParent $ mkUnboundName occ mkUnboundGRERdr :: RdrName -> GlobalRdrElt mkUnboundGRERdr rdr = mkLocalGRE UnboundGRE NoParent $ mkUnboundNameRdr rdr reportUnboundName :: WhatLooking -> RdrName -> RnM Name reportUnboundName what_look rdr = unboundName (LF what_look WL_Anywhere) rdr unboundName :: LookingFor -> RdrName -> RnM Name unboundName lf rdr = unboundNameX lf rdr [] unboundNameX :: LookingFor -> RdrName -> [GhcHint] -> RnM Name unboundNameX looking_for rdr_name hints = unboundNameOrTermInType NoTermInTypes looking_for rdr_name hints unboundTermNameInTypes :: LookingFor -> RdrName -> RdrName -> RnM Name unboundTermNameInTypes looking_for rdr_name demoted_rdr_name = unboundNameOrTermInType (UnknownTermInTypes demoted_rdr_name) looking_for rdr_name [] -- Catches imported qualified terms in type signatures -- with proper error message and suggestions termNameInType :: LookingFor -> RdrName -> RdrName -> [GhcHint] -> RnM Name termNameInType looking_for rdr_name demoted_rdr_name external_hints = unboundNameOrTermInType (TermInTypes demoted_rdr_name) looking_for rdr_name external_hints unboundNameOrTermInType :: IsTermInTypes -> LookingFor -> RdrName -> [GhcHint] -> RnM Name unboundNameOrTermInType if_term_in_type looking_for rdr_name hints = do { dflags <- getDynFlags ; let show_helpful_errors = gopt Opt_HelpfulErrors dflags ; if not show_helpful_errors then addErr =<< make_error [] hints else do { local_env <- getLocalRdrEnv ; global_env <- getGlobalRdrEnv ; impInfo <- getImports ; currmod <- getModule ; ic <- hsc_IC <$> getTopEnv ; let (imp_errs, suggs) = unknownNameSuggestions_ looking_for dflags ic currmod global_env local_env impInfo rdr_name ; traceTc "unboundNameOrTermInType" $ vcat [ text "rdr_name:" <+> ppr rdr_name , text "what_looking:" <+> text (show $ lf_which looking_for) , text "imp_errs:" <+> ppr imp_errs , text "suggs:" <+> ppr suggs ] ; addErr =<< make_error imp_errs (hints ++ suggs) } ; return (mkUnboundNameRdr rdr_name) } where name_to_search = case if_term_in_type of NoTermInTypes -> rdr_name UnknownTermInTypes demoted_name -> demoted_name TermInTypes demoted_name -> demoted_name err = notInScopeErr (lf_where looking_for) name_to_search make_error imp_errs hints = case if_term_in_type of TermInTypes demoted_name -> unknownNameSuggestionsMessage (TcRnTermNameInType demoted_name) [] -- no import errors hints _ -> unknownNameSuggestionsMessage (TcRnNotInScope err name_to_search) imp_errs hints unknownNameSuggestionsMessage :: TcRnMessage -> [ImportError] -> [GhcHint] -> RnM TcRnMessage unknownNameSuggestionsMessage msg imp_errs hints = do { unit_state <- hsc_units <$> getTopEnv ; hfdc <- getHoleFitDispConfig ; let supp = case NE.nonEmpty imp_errs of Nothing -> Nothing Just ne_imp_errs -> (Just (hfdc, [SupplementaryImportErrors ne_imp_errs])) ; return $ TcRnMessageWithInfo unit_state $ mkDetailedMessage (ErrInfo [] supp hints) msg } notInScopeErr :: WhereLooking -> RdrName -> NotInScopeError notInScopeErr where_look rdr_name | Just name <- isExact_maybe rdr_name = NoExactName name | WL_LocalTop <- where_look = NoTopLevelBinding | otherwise = NotInScope -- | Called from the typechecker ("GHC.Tc.Errors") when we find an unbound variable unknownNameSuggestions :: LocalRdrEnv -> WhatLooking -> RdrName -> RnM ([ImportError], [GhcHint]) unknownNameSuggestions lcl_env what_look tried_rdr_name = do { dflags <- getDynFlags ; rdr_env <- getGlobalRdrEnv ; imp_info <- getImports ; curr_mod <- getModule ; interactive_context <- hsc_IC <$> getTopEnv ; return $ unknownNameSuggestions_ (LF what_look WL_Anywhere) dflags interactive_context curr_mod rdr_env lcl_env imp_info tried_rdr_name } unknownNameSuggestions_ :: LookingFor -> DynFlags -> InteractiveContext -> Module -> GlobalRdrEnv -> LocalRdrEnv -> ImportAvails -> RdrName -> ([ImportError], [GhcHint]) unknownNameSuggestions_ looking_for dflags hpt curr_mod global_env local_env imports tried_rdr_name = (imp_errs, suggs) where suggs = mconcat [ if_ne (SuggestSimilarNames tried_rdr_name) $ similarNameSuggestions looking_for dflags global_env local_env tried_rdr_name , map (ImportSuggestion $ rdrNameOcc tried_rdr_name) imp_suggs , extensionSuggestions tried_rdr_name , fieldSelectorSuggestions global_env tried_rdr_name ] (imp_errs, imp_suggs) = importSuggestions looking_for hpt curr_mod imports tried_rdr_name if_ne :: (NonEmpty a -> b) -> [a] -> [b] if_ne _ [] = [] if_ne f (a : as) = [f (a :| as)] -- | When the name is in scope as field whose selector has been suppressed by -- NoFieldSelectors, display a helpful message explaining this. fieldSelectorSuggestions :: GlobalRdrEnv -> RdrName -> [GhcHint] fieldSelectorSuggestions global_env tried_rdr_name | null gres = [] | otherwise = [RemindFieldSelectorSuppressed tried_rdr_name parents] where gres = filter isNoFieldSelectorGRE $ lookupGRE global_env (LookupRdrName tried_rdr_name AllRelevantGREs) parents = [ parent | ParentIs parent <- map greParent gres ] similarNameSuggestions :: LookingFor -> DynFlags -> GlobalRdrEnv -> LocalRdrEnv -> RdrName -> [SimilarName] similarNameSuggestions looking_for@(LF what_look where_look) dflags global_env local_env tried_rdr_name = fuzzyLookup (showPpr dflags tried_rdr_name) all_possibilities where all_possibilities :: [(String, SimilarName)] all_possibilities = case what_look of WL_None -> [] _ -> [ (showPpr dflags r, SimilarRdrName r (Just $ LocallyBoundAt loc)) | (r,loc) <- local_possibilities local_env ] ++ [ (showPpr dflags r, rp) | (r, rp) <- global_possibilities global_env ] tried_occ = rdrNameOcc tried_rdr_name tried_is_sym = isSymOcc tried_occ tried_is_qual = isQual tried_rdr_name is_relevant sugg_occ = suggestionIsRelevant dflags what_look sugg_occ && isSymOcc sugg_occ == tried_is_sym -- Treat operator and non-operators as non-matching -- This heuristic avoids things like -- Not in scope 'f'; perhaps you meant '+' (from Prelude) local_ok = case where_look of { WL_Anywhere -> True ; WL_LocalOnly -> True ; _ -> False } local_possibilities :: LocalRdrEnv -> [(RdrName, SrcSpan)] local_possibilities env | tried_is_qual = [] | not local_ok = [] | otherwise = [ (mkRdrUnqual occ, nameSrcSpan name) | name <- localRdrEnvElts env , let occ = nameOccName name , is_relevant occ ] global_possibilities :: GlobalRdrEnv -> [(RdrName, SimilarName)] global_possibilities global_env | tried_is_qual = [ (rdr_qual, SimilarRdrName rdr_qual (Just how)) | gre <- globalRdrEnvElts global_env , isGreOk looking_for gre , let occ = greOccName gre , is_relevant occ , (mod, how) <- qualsInScope gre , let rdr_qual = mkRdrQual mod occ ] | otherwise = [ (rdr_unqual, sim) | gre <- globalRdrEnvElts global_env , isGreOk looking_for gre , let occ = greOccName gre rdr_unqual = mkRdrUnqual occ , is_relevant occ , sim <- case (unquals_in_scope gre, quals_only gre) of (how:_, _) -> [ SimilarRdrName rdr_unqual (Just how) ] ([], pr:_) -> [ pr ] -- See Note [Only-quals] ([], []) -> [] ] -- Note [Only-quals] -- ~~~~~~~~~~~~~~~~~ -- The second alternative returns those names with the same -- OccName as the one we tried, but live in *qualified* imports -- e.g. if you have: -- -- > import qualified Data.Map as Map -- > foo :: Map -- -- then we suggest @Map.Map@. -------------------- unquals_in_scope :: GlobalRdrElt -> [HowInScope] unquals_in_scope (gre@GRE { gre_lcl = lcl, gre_imp = is }) | lcl = [ LocallyBoundAt (greDefinitionSrcSpan gre) ] | otherwise = [ ImportedBy ispec | i <- bagToList is, let ispec = is_decl i , not (is_qual ispec) ] -------------------- quals_only :: GlobalRdrElt -> [SimilarName] -- Ones for which *only* the qualified version is in scope quals_only (gre@GRE { gre_imp = is }) = [ (SimilarRdrName (mkRdrQual (is_as ispec) (greOccName gre)) (Just $ ImportedBy ispec)) | i <- bagToList is, let ispec = is_decl i, is_qual ispec ] -- | Generate errors and helpful suggestions if a qualified name Mod.foo is not in scope. importSuggestions :: LookingFor -> InteractiveContext -> Module -> ImportAvails -> RdrName -> ([ImportError], [ImportSuggestion]) importSuggestions looking_for ic currMod imports rdr_name | WL_LocalOnly <- lf_where looking_for = ([], []) | WL_LocalTop <- lf_where looking_for = ([], []) | not (isQual rdr_name || isUnqual rdr_name) = ([], []) | Just name <- mod_name , show_not_imported_line name = ([MissingModule name], []) | is_qualified , null helpful_imports , (mod : mods) <- map fst interesting_imports = ([ModulesDoNotExport (mod :| mods) (lf_which looking_for) occ_name], []) | mod : mods <- helpful_imports_non_hiding = ([], [CouldImportFrom (mod :| mods)]) | mod : mods <- helpful_imports_hiding = ([], [CouldUnhideFrom (mod :| mods)]) | otherwise = ([], []) where is_qualified = isQual rdr_name (mod_name, occ_name) = case rdr_name of Unqual occ_name -> (Nothing, occ_name) Qual mod_name occ_name -> (Just mod_name, occ_name) _ -> panic "importSuggestions: dead code" -- What import statements provide "Mod" at all -- or, if this is an unqualified name, are not qualified imports interesting_imports = [ (mod, imp) | (mod, mod_imports) <- M.toList (imp_mods imports) , Just imp <- return $ pick (importedByUser mod_imports) ] -- Choose the imports from the interactive context which might have provided -- a module. interactive_imports = filter pick_interactive (ic_imports ic) pick_interactive :: InteractiveImport -> Bool pick_interactive (IIDecl d) | mod_name == Just (unLoc (ideclName d)) = True | mod_name == fmap unLoc (ideclAs d) = True pick_interactive (IIModule m) | mod_name == Just (moduleName m) = True pick_interactive _ = False -- We want to keep only one for each original module; preferably one with an -- explicit import list (for no particularly good reason) pick :: [ImportedModsVal] -> Maybe ImportedModsVal pick = listToMaybe . sortBy cmp . filter select where select imv = case mod_name of Just name -> imv_name imv == name Nothing -> not (imv_qualified imv) cmp = on compare imv_is_hiding S.<> on SrcLoc.leftmost_smallest imv_span -- Which of these would export a 'foo' -- (all of these are restricted imports, because if they were not, we -- wouldn't have an out-of-scope error in the first place) helpful_imports = filter helpful interesting_imports where helpful (_,imv) = any (isGreOk looking_for) $ lookupGRE (imv_all_exports imv) (LookupOccName occ_name $ RelevantGREsFOS WantNormal) -- Which of these do that because of an explicit hiding list resp. an -- explicit import list (helpful_imports_hiding, helpful_imports_non_hiding) = partition (imv_is_hiding . snd) helpful_imports -- See Note [When to show/hide the module-not-imported line] show_not_imported_line :: ModuleName -> Bool -- #15611 show_not_imported_line modnam | not (null interactive_imports) = False -- 1 (interactive context) | not (null interesting_imports) = False -- 1 (normal module import) | moduleName currMod == modnam = False -- 2 | otherwise = True extensionSuggestions :: RdrName -> [GhcHint] extensionSuggestions rdrName | rdrName == mkUnqual varName (fsLit "mdo") || rdrName == mkUnqual varName (fsLit "rec") = [SuggestExtension $ SuggestSingleExtension empty LangExt.RecursiveDo] | otherwise = [] qualsInScope :: GlobalRdrElt -> [(ModuleName, HowInScope)] -- Ones for which the qualified version is in scope qualsInScope gre@GRE { gre_lcl = lcl, gre_imp = is } | lcl = case greDefinitionModule gre of Nothing -> [] Just m -> [(moduleName m, LocallyBoundAt (greDefinitionSrcSpan gre))] | otherwise = [ (is_as ispec, ImportedBy ispec) | i <- bagToList is, let ispec = is_decl i ] isGreOk :: LookingFor -> GlobalRdrElt -> Bool isGreOk (LF what_look where_look) gre = what_ok && where_ok where -- when looking for record fields, what_ok checks whether the GRE is a -- record field. Otherwise, it checks whether the GRE is a record field -- defined in a module with -XNoFieldSelectors - it wouldn't be a useful -- suggestion in that case. what_ok = case what_look of WL_RecField -> isRecFldGRE gre _ -> not (isNoFieldSelectorGRE gre) where_ok = case where_look of WL_LocalTop -> isLocalGRE gre WL_LocalOnly -> False _ -> True -- | Is it OK to suggest an identifier in some other 'NameSpace', -- given what we are looking for? -- -- See Note [Related name spaces] suggestionIsRelevant :: DynFlags -- ^ to find out whether -XDataKinds is enabled -> WhatLooking -- ^ What kind of name are we looking for? -> OccName -- ^ The suggestion -- -- We only look at the suggestion's 'NameSpace', -- but passing the whole 'OccName' is convenient -- for debugging. -> Bool suggestionIsRelevant dflags what_looking suggestion = relevantNameSpace data_kinds what_looking suggestion_ns where suggestion_ns = occNameSpace suggestion data_kinds = xopt LangExt.DataKinds dflags -- | Is a 'NameSpace' relevant for what we are looking for? relevantNameSpace :: Bool -- ^ is @-XDataKinds@ enabled? -> WhatLooking -- ^ what are we looking for? -> NameSpace -- ^ is this 'NameSpace' relevant? -> Bool relevantNameSpace data_kinds = \case WL_Anything -> const True WL_TyCon -> isTcClsNameSpace WL_TyCon_or_TermVar -> isTcClsNameSpace <||> isTermVarOrFieldNameSpace WL_TyVar -> isTvNameSpace WL_Constructor -> isTcClsNameSpace <||> isDataConNameSpace WL_ConLike -> isDataConNameSpace WL_RecField -> isFieldNameSpace WL_Term -> isValNameSpace WL_TermVariable -> isTermVarOrFieldNameSpace WL_Type -> if data_kinds then not . isTermVarOrFieldNameSpace else not . isValNameSpace WL_None -> const False {- Note [Related name spaces] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Name spaces are related if there is a chance to mean the one when one writes the other, i.e. variables <-> data constructors and type variables <-> type constructors. In most contexts, this mistake can happen in both directions. Not so in patterns: When a user writes foo (just a) = ... It is possible that they meant to use `Just` instead. However, when they write foo (Map a) = ... It is unlikely that they mean to use `map`, since variables cannot be used here. Similarly, when we look for record fields, data constructors are not in a related namespace. Furthermore, with -XDataKinds, the data constructor name space is related to the type variable and type constructor name spaces. Note [When to show/hide the module-not-imported line] -- #15611 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For the error message: Not in scope X.Y Module X does not export Y No module named ‘X’ is imported: there are 2 cases, where we hide the last "no module is imported" line: 1. If the module X has been imported (normally or via interactive context). 2. It is the current module we are trying to compile then we can use the getModule function to get the current module name. (See test T15611a) -}