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Diffstat (limited to 'compiler/GHC/Rename/Unbound.hs')
| -rw-r--r-- | compiler/GHC/Rename/Unbound.hs | 384 |
1 files changed, 384 insertions, 0 deletions
diff --git a/compiler/GHC/Rename/Unbound.hs b/compiler/GHC/Rename/Unbound.hs new file mode 100644 index 0000000000..f8b33aa748 --- /dev/null +++ b/compiler/GHC/Rename/Unbound.hs @@ -0,0 +1,384 @@ +{- + +This module contains helper functions for reporting and creating +unbound variables. + +-} +module GHC.Rename.Unbound + ( mkUnboundName + , mkUnboundNameRdr + , isUnboundName + , reportUnboundName + , unknownNameSuggestions + , WhereLooking(..) + , unboundName + , unboundNameX + , notInScopeErr + ) +where + +import GhcPrelude + +import RdrName +import HscTypes +import TcRnMonad +import Name +import Module +import SrcLoc +import Outputable +import PrelNames ( mkUnboundName, isUnboundName, getUnique) +import Util +import Maybes +import DynFlags +import FastString +import Data.List +import Data.Function ( on ) +import UniqDFM (udfmToList) + +{- +************************************************************************ +* * + What to do when a lookup fails +* * +************************************************************************ +-} + +data WhereLooking = WL_Any -- 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 declaractions, + -- see Note [Renaming pattern synonym variables]) + +mkUnboundNameRdr :: RdrName -> Name +mkUnboundNameRdr rdr = mkUnboundName (rdrNameOcc rdr) + +reportUnboundName :: RdrName -> RnM Name +reportUnboundName rdr = unboundName WL_Any rdr + +unboundName :: WhereLooking -> RdrName -> RnM Name +unboundName wl rdr = unboundNameX wl rdr Outputable.empty + +unboundNameX :: WhereLooking -> RdrName -> SDoc -> RnM Name +unboundNameX where_look rdr_name extra + = do { dflags <- getDynFlags + ; let show_helpful_errors = gopt Opt_HelpfulErrors dflags + err = notInScopeErr rdr_name $$ extra + ; if not show_helpful_errors + then addErr err + else do { local_env <- getLocalRdrEnv + ; global_env <- getGlobalRdrEnv + ; impInfo <- getImports + ; currmod <- getModule + ; hpt <- getHpt + ; let suggestions = unknownNameSuggestions_ where_look + dflags hpt currmod global_env local_env impInfo + rdr_name + ; addErr (err $$ suggestions) } + ; return (mkUnboundNameRdr rdr_name) } + +notInScopeErr :: RdrName -> SDoc +notInScopeErr rdr_name + = hang (text "Not in scope:") + 2 (what <+> quotes (ppr rdr_name)) + where + what = pprNonVarNameSpace (occNameSpace (rdrNameOcc rdr_name)) + +type HowInScope = Either SrcSpan ImpDeclSpec + -- Left loc => locally bound at loc + -- Right ispec => imported as specified by ispec + + +-- | Called from the typechecker (TcErrors) when we find an unbound variable +unknownNameSuggestions :: DynFlags + -> HomePackageTable -> Module + -> GlobalRdrEnv -> LocalRdrEnv -> ImportAvails + -> RdrName -> SDoc +unknownNameSuggestions = unknownNameSuggestions_ WL_Any + +unknownNameSuggestions_ :: WhereLooking -> DynFlags + -> HomePackageTable -> Module + -> GlobalRdrEnv -> LocalRdrEnv -> ImportAvails + -> RdrName -> SDoc +unknownNameSuggestions_ where_look dflags hpt curr_mod global_env local_env + imports tried_rdr_name = + similarNameSuggestions where_look dflags global_env local_env tried_rdr_name $$ + importSuggestions where_look global_env hpt + curr_mod imports tried_rdr_name $$ + extensionSuggestions tried_rdr_name + + +similarNameSuggestions :: WhereLooking -> DynFlags + -> GlobalRdrEnv -> LocalRdrEnv + -> RdrName -> SDoc +similarNameSuggestions where_look dflags global_env + local_env tried_rdr_name + = case suggest of + [] -> Outputable.empty + [p] -> perhaps <+> pp_item p + ps -> sep [ perhaps <+> text "one of these:" + , nest 2 (pprWithCommas pp_item ps) ] + where + all_possibilities :: [(String, (RdrName, HowInScope))] + all_possibilities + = [ (showPpr dflags r, (r, Left loc)) + | (r,loc) <- local_possibilities local_env ] + ++ [ (showPpr dflags r, rp) | (r, rp) <- global_possibilities global_env ] + + suggest = fuzzyLookup (showPpr dflags tried_rdr_name) all_possibilities + perhaps = text "Perhaps you meant" + + pp_item :: (RdrName, HowInScope) -> SDoc + pp_item (rdr, Left loc) = pp_ns rdr <+> quotes (ppr rdr) <+> loc' -- Locally defined + where loc' = case loc of + UnhelpfulSpan l -> parens (ppr l) + RealSrcSpan l -> parens (text "line" <+> int (srcSpanStartLine l)) + pp_item (rdr, Right is) = pp_ns rdr <+> quotes (ppr rdr) <+> -- Imported + parens (text "imported from" <+> ppr (is_mod is)) + + pp_ns :: RdrName -> SDoc + pp_ns rdr | ns /= tried_ns = pprNameSpace ns + | otherwise = Outputable.empty + where ns = rdrNameSpace rdr + + tried_occ = rdrNameOcc tried_rdr_name + tried_is_sym = isSymOcc tried_occ + tried_ns = occNameSpace tried_occ + tried_is_qual = isQual tried_rdr_name + + correct_name_space occ = nameSpacesRelated (occNameSpace occ) tried_ns + && isSymOcc 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_Any -> 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 + , correct_name_space occ] + + global_possibilities :: GlobalRdrEnv -> [(RdrName, (RdrName, HowInScope))] + global_possibilities global_env + | tried_is_qual = [ (rdr_qual, (rdr_qual, how)) + | gre <- globalRdrEnvElts global_env + , isGreOk where_look gre + , let name = gre_name gre + occ = nameOccName name + , correct_name_space occ + , (mod, how) <- qualsInScope gre + , let rdr_qual = mkRdrQual mod occ ] + + | otherwise = [ (rdr_unqual, pair) + | gre <- globalRdrEnvElts global_env + , isGreOk where_look gre + , let name = gre_name gre + occ = nameOccName name + rdr_unqual = mkRdrUnqual occ + , correct_name_space occ + , pair <- case (unquals_in_scope gre, quals_only gre) of + (how:_, _) -> [ (rdr_unqual, 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_name = n, gre_lcl = lcl, gre_imp = is }) + | lcl = [ Left (nameSrcSpan n) ] + | otherwise = [ Right ispec + | i <- is, let ispec = is_decl i + , not (is_qual ispec) ] + + + -------------------- + quals_only :: GlobalRdrElt -> [(RdrName, HowInScope)] + -- Ones for which *only* the qualified version is in scope + quals_only (GRE { gre_name = n, gre_imp = is }) + = [ (mkRdrQual (is_as ispec) (nameOccName n), Right ispec) + | i <- is, let ispec = is_decl i, is_qual ispec ] + +-- | Generate helpful suggestions if a qualified name Mod.foo is not in scope. +importSuggestions :: WhereLooking + -> GlobalRdrEnv + -> HomePackageTable -> Module + -> ImportAvails -> RdrName -> SDoc +importSuggestions where_look global_env hpt currMod imports rdr_name + | WL_LocalOnly <- where_look = Outputable.empty + | not (isQual rdr_name || isUnqual rdr_name) = Outputable.empty + | null interesting_imports + , Just name <- mod_name + , show_not_imported_line name + = hsep + [ text "No module named" + , quotes (ppr name) + , text "is imported." + ] + | is_qualified + , null helpful_imports + , [(mod,_)] <- interesting_imports + = hsep + [ text "Module" + , quotes (ppr mod) + , text "does not export" + , quotes (ppr occ_name) <> dot + ] + | is_qualified + , null helpful_imports + , not (null interesting_imports) + , mods <- map fst interesting_imports + = hsep + [ text "Neither" + , quotedListWithNor (map ppr mods) + , text "exports" + , quotes (ppr occ_name) <> dot + ] + | [(mod,imv)] <- helpful_imports_non_hiding + = fsep + [ text "Perhaps you want to add" + , quotes (ppr occ_name) + , text "to the import list" + , text "in the import of" + , quotes (ppr mod) + , parens (ppr (imv_span imv)) <> dot + ] + | not (null helpful_imports_non_hiding) + = fsep + [ text "Perhaps you want to add" + , quotes (ppr occ_name) + , text "to one of these import lists:" + ] + $$ + nest 2 (vcat + [ quotes (ppr mod) <+> parens (ppr (imv_span imv)) + | (mod,imv) <- helpful_imports_non_hiding + ]) + | [(mod,imv)] <- helpful_imports_hiding + = fsep + [ text "Perhaps you want to remove" + , quotes (ppr occ_name) + , text "from the explicit hiding list" + , text "in the import of" + , quotes (ppr mod) + , parens (ppr (imv_span imv)) <> dot + ] + | not (null helpful_imports_hiding) + = fsep + [ text "Perhaps you want to remove" + , quotes (ppr occ_name) + , text "from the hiding clauses" + , text "in one of these imports:" + ] + $$ + nest 2 (vcat + [ quotes (ppr mod) <+> parens (ppr (imv_span imv)) + | (mod,imv) <- helpful_imports_hiding + ]) + | otherwise + = Outputable.empty + 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) + _ -> error "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) <- moduleEnvToList (imp_mods imports) + , Just imp <- return $ pick (importedByUser mod_imports) + ] + + -- 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 (compare `on` prefer) . filter select + where select imv = case mod_name of Just name -> imv_name imv == name + Nothing -> not (imv_qualified imv) + prefer imv = (imv_is_hiding imv, imv_span imv) + + -- 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) + = not . null $ lookupGlobalRdrEnv (imv_all_exports imv) occ_name + + -- 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 + | modnam `elem` globMods = False -- #14225 -- 1 + | moduleName currMod == modnam = False -- 2.1 + | is_last_loaded_mod modnam hpt_uniques = False -- 2.2 + | otherwise = True + where + hpt_uniques = map fst (udfmToList hpt) + is_last_loaded_mod _ [] = False + is_last_loaded_mod modnam uniqs = last uniqs == getUnique modnam + globMods = nub [ mod + | gre <- globalRdrEnvElts global_env + , isGreOk where_look gre + , (mod, _) <- qualsInScope gre + ] + +extensionSuggestions :: RdrName -> SDoc +extensionSuggestions rdrName + | rdrName == mkUnqual varName (fsLit "mdo") || + rdrName == mkUnqual varName (fsLit "rec") + = text "Perhaps you meant to use RecursiveDo" + | otherwise = Outputable.empty + +qualsInScope :: GlobalRdrElt -> [(ModuleName, HowInScope)] +-- Ones for which the qualified version is in scope +qualsInScope GRE { gre_name = n, gre_lcl = lcl, gre_imp = is } + | lcl = case nameModule_maybe n of + Nothing -> [] + Just m -> [(moduleName m, Left (nameSrcSpan n))] + | otherwise = [ (is_as ispec, Right ispec) + | i <- is, let ispec = is_decl i ] + +isGreOk :: WhereLooking -> GlobalRdrElt -> Bool +isGreOk where_look = case where_look of + WL_LocalTop -> isLocalGRE + WL_LocalOnly -> const False + _ -> const True + +{- 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. +2. If the module X is the current module. There are 2 subcases: + 2.1 If the unknown module name is in a input source file, + then we can use the getModule function to get the current module name. + (See test T15611a) + 2.2 If the unknown module name has been entered by the user in GHCi, + then the getModule function returns something like "interactive:Ghci1", + and we have to check the current module in the last added entry of + the HomePackageTable. (See test T15611b) +-} |