import DynFlags
import HsSyn
+import TcEnv ( isBrackStage )
import RnEnv
import RnHsDoc ( rnHsDoc )
import IfaceEnv ( ifaceExportNames )
import Name
import NameEnv
import NameSet
-import OccName
import HscTypes
import RdrName
import Outputable
import SrcLoc
import FiniteMap
import ErrUtils
-import BasicTypes ( WarningTxt(..) )
-import DriverPhases ( isHsBoot )
import Util
import FastString
import ListSetOps
-import Data.List ( partition, concatMap, (\\), delete )
+import Data.List ( partition, (\\), delete )
+import qualified Data.Set as Set
import IO ( openFile, IOMode(..) )
import Monad ( when, mplus )
\end{code}
implicit_prelude <- doptM Opt_ImplicitPrelude
let prel_imports = mkPrelImports this_mod implicit_prelude imports
(source, ordinary) = partition is_source_import imports
- is_source_import (L _ (ImportDecl _ is_boot _ _ _)) = is_boot
+ is_source_import (L _ (ImportDecl _ _ is_boot _ _ _)) = is_boot
ifOptM Opt_WarnImplicitPrelude (
when (notNull prel_imports) $ addWarn (implicitPreludeWarn)
| otherwise = [preludeImportDecl]
where
explicit_prelude_import
- = notNull [ () | L _ (ImportDecl mod _ _ _ _) <- import_decls,
+ = notNull [ () | L _ (ImportDecl mod Nothing _ _ _ _) <- import_decls,
unLoc mod == pRELUDE_NAME ]
preludeImportDecl :: LImportDecl RdrName
preludeImportDecl
= L loc $
ImportDecl (L loc pRELUDE_NAME)
+ Nothing {- no specific package -}
False {- Not a boot interface -}
False {- Not qualified -}
Nothing {- No "as" -}
-> LImportDecl RdrName
-> RnM (LImportDecl Name, GlobalRdrEnv, ImportAvails,AnyHpcUsage)
-rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name want_boot
+rnImportDecl this_mod (L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot
qual_only as_mod imp_details))
- =
- setSrcSpan loc $ do
+ = setSrcSpan loc $ do
+
+ when (isJust mb_pkg) $ do
+ pkg_imports <- doptM Opt_PackageImports
+ when (not pkg_imports) $ addErr packageImportErr
-- If there's an error in loadInterface, (e.g. interface
-- file not found) we get lots of spurious errors from 'filterImports'
imp_mod_name = unLoc loc_imp_mod_name
doc = ppr imp_mod_name <+> ptext (sLit "is directly imported")
- iface <- loadSrcInterface doc imp_mod_name want_boot
+ iface <- loadSrcInterface doc imp_mod_name want_boot mb_pkg
-- Compiler sanity check: if the import didn't say
-- {-# SOURCE #-} we should not get a hi-boot file
-- Issue a user warning for a redundant {- SOURCE -} import
-- NB that we arrange to read all the ordinary imports before
- -- any of the {- SOURCE -} imports
- warnIf (want_boot && not (mi_boot iface))
+ -- any of the {- SOURCE -} imports.
+ --
+ -- in --make and GHCi, the compilation manager checks for this,
+ -- and indeed we shouldn't do it here because the existence of
+ -- the non-boot module depends on the compilation order, which
+ -- is not deterministic. The hs-boot test can show this up.
+ dflags <- getDOpts
+ warnIf (want_boot && not (mi_boot iface) && isOneShot (ghcMode dflags))
(warnRedundantSourceImport imp_mod_name)
let
_ -> return ()
)
- let new_imp_decl = L loc (ImportDecl loc_imp_mod_name want_boot
+ let new_imp_decl = L loc (ImportDecl loc_imp_mod_name mb_pkg want_boot
qual_only as_mod new_imp_details)
return (new_imp_decl, gbl_env, imports, mi_hpc iface)
* the ImportAvails
created by its bindings.
-Note [Shadowing in extendGlobalRdrEnvRn]
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Usually when etending the GlobalRdrEnv we complain if a new binding
-duplicates an existing one. By adding the bindings one at a time,
-this check also complains if we add two new bindings for the same name.
-(Remember that in Template Haskell the duplicates might *already be*
-in the GlobalRdrEnv from higher up the module.)
-
-But with a Template Haskell quotation we want to *shadow*:
+Note [Top-level Names in Template Haskell decl quotes]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider a Template Haskell declaration quotation like this:
+ module M where
f x = h [d| f = 3 |]
-Here the inner binding for 'f' simply shadows the outer one.
-And that applies even if the binding for 'f' is in a where-clause,
-and hence is in the *local* RdrEnv not the *global* RdrEnv.
+When renaming the declarations inside [d| ...|], we treat the
+top level binders specially in two ways
+
+1. We give them an Internal name, not (as usual) an External one.
+ Otherwise the NameCache gets confused by a second allocation of
+ M.f. (We used to invent a fake module ThFake to avoid this, but
+ that had other problems, notably in getting the correct answer for
+ nameIsLocalOrFrom in lookupFixity. So we now leave tcg_module
+ unaffected.)
+
+2. We make them *shadow* the outer bindings. If we don't do that,
+ we'll get a complaint when extending the GlobalRdrEnv, saying that
+ there are two bindings for 'f'.
+
+ This shadowing applies even if the binding for 'f' is in a
+ where-clause, and hence is in the *local* RdrEnv not the *global*
+ RdrEnv.
-Hence the shadowP boolean passed in.
+We find out whether we are inside a [d| ... |] by testing the TH
+stage. This is a slight hack, because the stage field was really meant for
+the type checker, and here we are not interested in the fields of Brack,
+hence the error thunks in thRnBrack.
\begin{code}
-extendGlobalRdrEnvRn :: Bool -- Note [Shadowing in extendGlobalRdrEnvRn]
- -> [AvailInfo]
+extendGlobalRdrEnvRn :: [AvailInfo]
-> MiniFixityEnv
-> RnM (TcGblEnv, TcLclEnv)
-- Updates both the GlobalRdrEnv and the FixityEnv
-- We return a new TcLclEnv only becuase we might have to
- -- delete some bindings from it; see Note [Shadowing in extendGlobalRdrEnvRn]
+ -- delete some bindings from it;
+ -- see Note [Top-level Names in Template Haskell decl quotes]
-extendGlobalRdrEnvRn shadowP avails new_fixities
+extendGlobalRdrEnvRn avails new_fixities
= do { (gbl_env, lcl_env) <- getEnvs
+ ; stage <- getStage
; let rdr_env = tcg_rdr_env gbl_env
fix_env = tcg_fix_env gbl_env
-- Delete new_occs from global and local envs
- -- We are going to shadow them
- -- See Note [Shadowing in extendGlobalRdrEnvRn]
+ -- If we are in a TemplateHaskell decl bracket,
+ -- we are going to shadow them
+ -- See Note [Top-level Names in Template Haskell decl quotes]
+ shadowP = isBrackStage stage
new_occs = map (nameOccName . gre_name) gres
rdr_env1 = hideSomeUnquals rdr_env new_occs
lcl_env1 = lcl_env { tcl_rdr = delListFromOccEnv (tcl_rdr lcl_env) new_occs }
-
- -- Note [Shadowing in extendGlobalRdrEnvRn]
(rdr_env2, lcl_env2) | shadowP = (rdr_env1, lcl_env1)
| otherwise = (rdr_env, lcl_env)
Instances of type families
~~~~~~~~~~~~~~~~~~~~~~~~~~
-Indexed data/newtype instances contain data constructors that we need to
-collect, too. Moreover, we need to descend into the data/newtypes instances
-of associated families.
+Family instances contain data constructors that we need to collect and we also
+need to descend into the type instances of associated families in class
+instances. The type constructor of a family instance is a usage occurence.
+Hence, we don't return it as a subname in 'AvailInfo'; otherwise, we would get
+a duplicate declaration error.
+
+Note [Looking up family names in family instances]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Consider
+
+ module M where
+ type family T a :: *
+ type instance M.T Int = Bool
+
+We might think that we can simply use 'lookupOccRn' when processing the type
+instance to look up 'M.T'. Alas, we can't! The type family declaration is in
+the *same* HsGroup as the type instance declaration. Hence, as we are
+currently collecting the binders declared in that HsGroup, these binders will
+not have been added to the global environment yet.
+
+In the case of type classes, this problem does not arise, as a class instance
+does not define any binders of it's own. So, we simply don't attempt to look
+up the class names of class instances in 'get_local_binders' below.
-We need to be careful with the handling of the type constructor of each type
-instance as the family constructor is already defined, and we want to avoid
-raising a duplicate declaration error. So, we make a new name for it, but
-don't return it in the 'AvailInfo'.
+If we don't look up class instances, can't we get away without looking up type
+instances, too? No, we can't. Data type instances define data constructors
+and we need to
+
+ (1) collect those in 'get_local_binders' and
+ (2) we need to get their parent name in 'get_local_binders', too, to
+ produce an appropriate 'AvailTC'.
+
+This parent name is exactly the family name of the type instance that is so
+difficult to look up.
+
+We solve this problem as follows:
+
+ (a) We process all type declarations other than type instances first.
+ (b) Then, we compute a 'GlobalRdrEnv' from the result of the first step.
+ (c) Finally, we process all type instances (both those on the toplevel and
+ those nested in class instances) and check for the family names in the
+ 'GlobalRdrEnv' produced in the previous step before using 'lookupOccRn'.
\begin{code}
getLocalNonValBinders :: HsGroup RdrName -> RnM [AvailInfo]
hs_tyclds = tycl_decls,
hs_instds = inst_decls,
hs_fords = foreign_decls })
- = do { tc_names_s <- mapM new_tc tycl_decls
- ; at_names_s <- mapM inst_ats inst_decls
- ; val_names <- mapM new_simple val_bndrs
- ; return (val_names ++ tc_names_s ++ concat at_names_s) }
+ = do { -- separate out the family instance declarations
+ let (tyinst_decls1, tycl_decls_noinsts)
+ = partition (isFamInstDecl . unLoc) tycl_decls
+ tyinst_decls = tyinst_decls1 ++
+ concatMap (instDeclATs . unLoc) inst_decls
+
+ -- process all type/class decls except family instances
+ ; tc_names <- mapM new_tc tycl_decls_noinsts
+
+ -- create a temporary rdr env of the type binders
+ ; let tc_gres = gresFromAvails LocalDef tc_names
+ tc_name_env = foldl extendGlobalRdrEnv emptyGlobalRdrEnv tc_gres
+
+ -- process all family instances
+ ; ti_names <- mapM (new_ti tc_name_env) tyinst_decls
+
+ -- finish off with value binder in case of a hs-boot file
+ ; val_names <- mapM new_simple val_bndrs
+ ; return (val_names ++ tc_names ++ ti_names) }
where
mod = tcg_mod gbl_env
is_hs_boot = isHsBoot (tcg_src gbl_env) ;
+ for_hs_bndrs :: [Located RdrName]
for_hs_bndrs = [nm | L _ (ForeignImport nm _ _) <- foreign_decls]
-- In a hs-boot file, the value binders come from the
-- *signatures*, and there should be no foreign binders
+ val_bndrs :: [Located RdrName]
val_bndrs | is_hs_boot = [nm | L _ (TypeSig nm _) <- val_sigs]
| otherwise = for_hs_bndrs
+ new_simple :: Located RdrName -> RnM (GenAvailInfo Name)
new_simple rdr_name = do
nm <- newTopSrcBinder mod rdr_name
return (Avail nm)
- new_tc tc_decl
- | isFamInstDecl (unLoc tc_decl)
- = do { main_name <- lookupFamInstDeclBndr mod main_rdr
- ; sub_names <- mapM (newTopSrcBinder mod) sub_rdrs
- ; return (AvailTC main_name sub_names) }
- -- main_name is not bound here!
- | otherwise
+ new_tc tc_decl -- NOT for type/data instances
= do { main_name <- newTopSrcBinder mod main_rdr
; sub_names <- mapM (newTopSrcBinder mod) sub_rdrs
; return (AvailTC main_name (main_name : sub_names)) }
where
(main_rdr : sub_rdrs) = tyClDeclNames (unLoc tc_decl)
- inst_ats inst_decl
- = mapM new_tc (instDeclATs (unLoc inst_decl))
+ new_ti tc_name_env ti_decl -- ONLY for type/data instances
+ = do { main_name <- lookupFamInstDeclBndr tc_name_env main_rdr
+ ; sub_names <- mapM (newTopSrcBinder mod) sub_rdrs
+ ; return (AvailTC main_name sub_names) }
+ -- main_name is not bound here!
+ where
+ (main_rdr : sub_rdrs) = tyClDeclNames (unLoc ti_decl)
get_local_binders _ g = pprPanic "get_local_binders" (ppr g)
\end{code}
emptyAvailEnv :: AvailEnv
emptyAvailEnv = emptyNameEnv
+{- Dead code
unitAvailEnv :: AvailInfo -> AvailEnv
unitAvailEnv a = unitNameEnv (availName a) a
availEnvElts :: AvailEnv -> [AvailInfo]
availEnvElts = nameEnvElts
+-}
addAvail :: AvailEnv -> AvailInfo -> AvailEnv
addAvail avails avail = extendNameEnv_C plusAvail avails (availName avail) avail
tcg_dus = tcg_dus tcg_env `plusDU`
usesOnly (availsToNameSet final_avails) }) }
-
exports_from_avail :: Maybe [LIE RdrName]
-- Nothing => no explicit export list
-> GlobalRdrEnv
| otherwise
= do { implicit_prelude <- doptM Opt_ImplicitPrelude
- ; let { exportValid = (mod `elem` imported_modules)
+ ; let { exportValid = (mod `elem` imported_modules)
|| (moduleName this_mod == mod)
- ; gres = filter (isModuleExported implicit_prelude mod)
- (globalRdrEnvElts rdr_env)
- }
+ ; gres = filter (isModuleExported implicit_prelude mod)
+ (globalRdrEnvElts rdr_env)
+ ; names = map gre_name gres
+ }
- ; checkErr exportValid (moduleNotImported mod)
+ ; checkErr exportValid (moduleNotImported mod)
; warnIf (exportValid && null gres) (nullModuleExport mod)
- ; occs' <- check_occs ie occs (map gre_name gres)
+ ; addUsedRdrNames (concat [ [mkRdrQual mod occ, mkRdrUnqual occ]
+ | occ <- map nameOccName names ])
+ -- The qualified and unqualified version of all of
+ -- these names are, in effect, used by this export
+
+ ; occs' <- check_occs ie occs names
-- This check_occs not only finds conflicts
-- between this item and others, but also
-- internally within this item. That is, if
-- every module that imports the Prelude
| otherwise
= case prov of
- LocalDef -> moduleName (nameModule name) == mod
+ LocalDef | Just name_mod <- nameModule_maybe name
+ -> moduleName name_mod == mod
+ | otherwise -> False
Imported is -> any unQualSpecOK is && any (qualSpecOK mod) is
-------------------------------
(parens imp_msg) <> colon,
(ppr deprec_txt) ])
where
- name_mod = nameModule name
+ name_mod = ASSERT2( isExternalName name, ppr name ) nameModule name
imp_mod = importSpecModule imp_spec
imp_msg = ptext (sLit "imported from") <+> ppr imp_mod <> extra
extra | imp_mod == moduleName name_mod = empty
-> GlobalRdrElt -> Maybe WarningTxt
-- The name is definitely imported, so look in HPT, PIT
lookupImpDeprec dflags hpt pit gre
- = case lookupIfaceByModule dflags hpt pit (nameModule name) of
+ = case lookupIfaceByModule dflags hpt pit mod of
Just iface -> mi_warn_fn iface name `mplus` -- Bleat if the thing, *or
case gre_par gre of
ParentIs p -> mi_warn_fn iface p -- its parent*, is warn'd
Nothing -> Nothing -- See Note [Used names with interface not loaded]
where
- name = gre_name gre
+ name = gre_name gre
+ mod = ASSERT2( isExternalName name, ppr name ) nameModule name
\end{code}
Note [Used names with interface not loaded]
\begin{code}
reportUnusedNames :: Maybe [LIE RdrName] -- Export list
-> TcGblEnv -> RnM ()
-reportUnusedNames export_decls gbl_env
+reportUnusedNames _export_decls gbl_env
= do { traceRn ((text "RUN") <+> (ppr (tcg_dus gbl_env)))
- ; warnUnusedTopBinds unused_locals
- ; warnUnusedModules unused_imp_mods
- ; warnUnusedImports unused_imports
- ; warnDuplicateImports defined_and_used
- ; printMinimalImports minimal_imports }
+ ; warnUnusedImportDecls gbl_env
+ ; warnUnusedTopBinds unused_locals }
where
used_names :: NameSet
used_names = findUses (tcg_dus gbl_env) emptyNameSet
-- Note that defined_and_used, defined_but_not_used
-- are both [GRE]; that's why we need defined_and_used
-- rather than just used_names
- defined_and_used, defined_but_not_used :: [GlobalRdrElt]
- (defined_and_used, defined_but_not_used)
+ _defined_and_used, defined_but_not_used :: [GlobalRdrElt]
+ (_defined_and_used, defined_but_not_used)
= partition (gre_is_used used_names) defined_names
kids_env = mkChildEnv defined_names
unused_locals = filter is_unused_local defined_but_not_used
is_unused_local :: GlobalRdrElt -> Bool
is_unused_local gre = isLocalGRE gre && isExternalName (gre_name gre)
-
- unused_imports :: [GlobalRdrElt]
- unused_imports = mapCatMaybes unused_imp defined_but_not_used
- unused_imp :: GlobalRdrElt -> Maybe GlobalRdrElt -- Result has trimmed Imported provenances
- unused_imp (GRE {gre_prov = LocalDef}) = Nothing
- unused_imp gre@(GRE {gre_prov = Imported imp_specs})
- | null trimmed_specs = Nothing
- | otherwise = Just (gre {gre_prov = Imported trimmed_specs})
- where
- trimmed_specs = filter report_if_unused imp_specs
-
- -- To figure out the minimal set of imports, start with the things
- -- that are in scope (i.e. in gbl_env). Then just combine them
- -- into a bunch of avails, so they are properly grouped
- --
- -- BUG WARNING: this does not deal properly with qualified imports!
- minimal_imports :: FiniteMap ModuleName AvailEnv
- minimal_imports0 = foldr add_expall emptyFM expall_mods
- minimal_imports1 = foldr add_name minimal_imports0 defined_and_used
- minimal_imports = foldr add_inst_mod minimal_imports1 direct_import_mods
- -- The last line makes sure that we retain all direct imports
- -- even if we import nothing explicitly.
- -- It's not necessarily redundant to import such modules. Consider
- -- module This
- -- import M ()
- --
- -- The import M() is not *necessarily* redundant, even if
- -- we suck in no instance decls from M (e.g. it contains
- -- no instance decls, or This contains no code). It may be
- -- that we import M solely to ensure that M's orphan instance
- -- decls (or those in its imports) are visible to people who
- -- import This. Sigh.
- -- There's really no good way to detect this, so the error message
- -- in RnEnv.warnUnusedModules is weakened instead
-
- -- We've carefully preserved the provenance so that we can
- -- construct minimal imports that import the name by (one of)
- -- the same route(s) as the programmer originally did.
- add_name gre@(GRE {gre_prov = Imported (imp_spec:_)}) acc
- = addToFM_C plusAvailEnv acc
- (importSpecModule imp_spec) (unitAvailEnv (greAvail gre))
- add_name _ acc = acc -- Local
-
- -- Modules mentioned as 'module M' in the export list
- expall_mods = case export_decls of
- Nothing -> []
- Just es -> [m | L _ (IEModuleContents m) <- es]
-
- -- This is really bogus. The idea is that if we see 'module M' in
- -- the export list we must retain the import decls that drive it
- -- If we aren't careful we might see
- -- module A( module M ) where
- -- import M
- -- import N
- -- and suppose that N exports everything that M does. Then we
- -- must not drop the import of M even though N brings it all into
- -- scope.
- --
- -- BUG WARNING: 'module M' exports aside, what if M.x is mentioned?!
- --
- -- The reason that add_expall is bogus is that it doesn't take
- -- qualified imports into account. But it's an improvement.
- add_expall mod acc = addToFM_C plusAvailEnv acc mod emptyAvailEnv
+\end{code}
- add_inst_mod (mod, _) acc
- | mod_name `elemFM` acc = acc -- We import something already
- | otherwise = addToFM acc mod_name emptyAvailEnv
+%*********************************************************
+%* *
+ Unused imports
+%* *
+%*********************************************************
+
+This code finds which import declarations are unused. The
+specification and implementation notes are here:
+ http://hackage.haskell.org/trac/ghc/wiki/Commentary/Compiler/UnusedImports
+
+\begin{code}
+type ImportDeclUsage
+ = ( LImportDecl Name -- The import declaration
+ , [AvailInfo] -- What *is* used (normalised)
+ , [Name] ) -- What is imported but *not* used
+\end{code}
+
+\begin{code}
+warnUnusedImportDecls :: TcGblEnv -> RnM ()
+warnUnusedImportDecls gbl_env
+ = do { uses <- readMutVar (tcg_used_rdrnames gbl_env)
+ ; let imports = filter explicit_import (tcg_rn_imports gbl_env)
+ rdr_env = tcg_rdr_env gbl_env
+
+ ; let usage :: [ImportDeclUsage]
+ usage = findImportUsage imports rdr_env (Set.elems uses)
+
+ ; ifOptM Opt_WarnUnusedImports $
+ mapM_ warnUnusedImport usage
+
+ ; ifOptM Opt_D_dump_minimal_imports $
+ printMinimalImports usage }
+ where
+ explicit_import (L loc _) = isGoodSrcSpan loc
+ -- Filter out the implicit Prelude import
+ -- which we do not want to bleat about
+\end{code}
+
+\begin{code}
+findImportUsage :: [LImportDecl Name]
+ -> GlobalRdrEnv
+ -> [RdrName]
+ -> [ImportDeclUsage]
+
+type ImportMap = FiniteMap SrcLoc [AvailInfo]
+ -- The intermediate data struture records, for each import
+ -- declaration, what stuff brought into scope by that
+ -- declaration is actually used in the module.
+ --
+ -- The SrcLoc is the location of the start
+ -- of a particular 'import' declaration
+ --
+ -- The AvailInfos are the things imported from that decl
+ -- (just a list, not normalised)
+
+findImportUsage imports rdr_env rdrs
+ = map unused_decl imports
+ where
+ import_usage :: ImportMap
+ import_usage = foldr add_rdr emptyFM rdrs
+
+ unused_decl decl@(L loc (ImportDecl { ideclHiding = imps }))
+ = (decl, nubAvails used_avails, unused_imps)
where
- mod_name = moduleName mod
- -- Add an empty collection of imports for a module
- -- from which we have sucked only instance decls
-
- imports = tcg_imports gbl_env
-
- direct_import_mods :: [(Module, [(ModuleName, Bool, SrcSpan)])]
- -- See the type of the imp_mods for this triple
- direct_import_mods = fmToList (imp_mods imports)
-
- -- unused_imp_mods are the directly-imported modules
- -- that are not mentioned in minimal_imports1
- -- [Note: not 'minimal_imports', because that includes directly-imported
- -- modules even if we use nothing from them; see notes above]
- --
- -- BUG WARNING: this code is generally buggy
- unused_imp_mods :: [(ModuleName, SrcSpan)]
- unused_imp_mods = [(mod_name,loc)
- | (mod, xs) <- direct_import_mods,
- (_, no_imp, loc) <- xs,
- let mod_name = moduleName mod,
- not (mod_name `elemFM` minimal_imports1),
- mod /= pRELUDE,
- not no_imp]
- -- The not no_imp part is not to complain about
- -- import M (), which is an idiom for importing
- -- instance declarations
-
- module_unused :: ModuleName -> Bool
- module_unused mod = any (((==) mod) . fst) unused_imp_mods
-
- report_if_unused :: ImportSpec -> Bool
- -- Do we want to report this as an unused import?
- report_if_unused (ImpSpec {is_decl = d, is_item = i})
- = not (module_unused (is_mod d)) -- Not if we've already said entire import is unused
- && isExplicitItem i -- Only if the import was explicit
+ used_avails = lookupFM import_usage (srcSpanStart loc) `orElse` []
+ used_names = availsToNameSet used_avails
+
+ unused_imps = case imps of
+ Just (False, imp_ies) -> nameSetToList unused_imps
+ where
+ imp_names = mkNameSet (concatMap (ieNames . unLoc) imp_ies)
+ unused_imps = imp_names `minusNameSet` used_names
+
+ _other -> [] -- No explicit import list => no unused-name list
----------------------
-warnDuplicateImports :: [GlobalRdrElt] -> RnM ()
--- Given the GREs for names that are used, figure out which imports
--- could be omitted without changing the top-level environment.
---
--- NB: Given import Foo( T )
--- import qualified Foo
--- we do not report a duplicate import, even though Foo.T is brought
--- into scope by both, because there's nothing you can *omit* without
--- changing the top-level environment. So we complain only if it's
--- explicitly named in both imports or neither.
---
--- Furthermore, we complain about Foo.T only if
--- there is no complaint about (unqualified) T
-
-warnDuplicateImports gres
- = ifOptM Opt_WarnUnusedImports $
- sequence_ [ warn name pr
- | GRE { gre_name = name, gre_prov = Imported imps } <- gres
- , pr <- redundants imps ]
+ add_rdr :: RdrName -> ImportMap -> ImportMap
+ add_rdr rdr iu
+ = case lookupGRE_RdrName rdr rdr_env of
+ [gre] | Imported imps <- gre_prov gre
+ -> add_imp gre (bestImport imps) iu
+ _other -> iu
+
+ add_imp :: GlobalRdrElt -> ImportSpec -> ImportMap -> ImportMap
+ add_imp gre (ImpSpec { is_decl = imp_decl_spec }) iu
+ = addToFM_C add iu decl_loc [avail]
+ where
+ add avails _ = avail : avails
+ decl_loc = srcSpanStart (is_dloc imp_decl_spec)
+ name = gre_name gre
+ avail = case gre_par gre of
+ ParentIs p -> AvailTC p [p,name]
+ NoParent | isTyConName name -> AvailTC name [name]
+ | otherwise -> Avail name
+ -- If you use (+) from Num, then for this purpose we want
+ -- to say that Num is used as well. That is why in the
+ -- ParentIs case we have [p,name] in the ParentIs case
+
+bestImport :: [ImportSpec] -> ImportSpec
+bestImport iss
+ = case partition isImpAll iss of
+ ([], imp_somes) -> textuallyFirst imp_somes
+ (imp_alls, _) -> textuallyFirst imp_alls
+
+textuallyFirst :: [ImportSpec] -> ImportSpec
+textuallyFirst iss = case sortWith (is_dloc . is_decl) iss of
+ [] -> pprPanic "textuallyFirst" (ppr iss)
+ (is:_) -> is
+
+isImpAll :: ImportSpec -> Bool
+isImpAll (ImpSpec { is_item = ImpAll }) = True
+isImpAll _other = False
+\end{code}
+
+\begin{code}
+warnUnusedImport :: ImportDeclUsage -> RnM ()
+warnUnusedImport (L loc decl, used, unused)
+ | Just (False,[]) <- ideclHiding decl
+ = return () -- Do not warn for 'import M()'
+ | null used = addWarnAt loc msg1 -- Nothing used; drop entire decl
+ | null unused = return () -- Everything imported is used; nop
+ | otherwise = addWarnAt loc msg2 -- Some imports are unused
where
- warn name (red_imp, cov_imp)
- = addWarnAt (importSpecLoc red_imp)
- (vcat [ptext (sLit "Redundant import of:") <+> quotes pp_name,
- ptext (sLit "It is also") <+> ppr cov_imp])
- where
- pp_name | is_qual red_decl = ppr (is_as red_decl) <> dot <> ppr occ
- | otherwise = ppr occ
- occ = nameOccName name
- red_decl = is_decl red_imp
-
- redundants :: [ImportSpec] -> [(ImportSpec,ImportSpec)]
- -- The returned pair is (redundant-import, covering-import)
- redundants imps
- = [ (red_imp, cov_imp)
- | red_imp <- imps
- , isExplicitItem (is_item red_imp)
- -- Complain only about redundant imports
- -- mentioned explicitly by the user
- , cov_imp <- take 1 (filter (covers red_imp) imps) ]
- -- The 'take 1' picks the first offending group
- -- for this particular name
-
- -- "red_imp" is a putative redundant import
- -- "cov_imp" potentially covers it
- -- This test decides whether red_imp could be dropped
- --
- -- NOTE: currently the test does not warn about
- -- import M( x )
- -- import N( x )
- -- even if the same underlying 'x' is involved, because dropping
- -- either import would change the qualified names in scope (M.x, N.x)
- -- But if the qualified names aren't used, the import is indeed redundant
- -- Sadly we don't know that. Oh well.
- covers red_imp@(ImpSpec { is_decl = red_decl })
- cov_imp@(ImpSpec { is_decl = cov_decl, is_item = cov_item })
- | red_loc == cov_loc
- = False -- Ignore diagonal elements
- | not (is_as red_decl == is_as cov_decl)
- = False -- They bring into scope different qualified names
- | not (is_qual red_decl) && is_qual cov_decl
- = False -- Covering one doesn't bring unqualified name into scope
- | otherwise
- = not (isExplicitItem cov_item) -- Redundant one is selective and covering one isn't
- || red_later -- or both are explicit; tie-break using red_later
-{-
- | red_selective
- = not cov_selective -- Redundant one is selective and covering one isn't
- || red_later -- Both are explicit; tie-break using red_later
- | otherwise
- = not cov_selective -- Neither import is selective
- && (is_mod red_decl == is_mod cov_decl) -- They import the same module
- && red_later -- Tie-break
--}
- where
- red_loc = importSpecLoc red_imp
- cov_loc = importSpecLoc cov_imp
- red_later = red_loc > cov_loc
-
--- ToDo: deal with original imports with 'qualified' and 'as M' clauses
-printMinimalImports :: FiniteMap ModuleName AvailEnv -- Minimal imports
- -> RnM ()
-printMinimalImports imps
- = ifOptM Opt_D_dump_minimal_imports $ do {
-
- mod_ies <- initIfaceTcRn $ mapM to_ies (fmToList imps) ;
- this_mod <- getModule ;
- rdr_env <- getGlobalRdrEnv ;
- dflags <- getDOpts ;
- liftIO $ do h <- openFile (mkFilename this_mod) WriteMode
- printForUser h (mkPrintUnqualified dflags rdr_env)
- (vcat (map ppr_mod_ie mod_ies))
- }
+ msg1 = vcat [pp_herald <+> quotes pp_mod <+> pp_not_used,
+ nest 2 (ptext (sLit "except perhaps to import instances from")
+ <+> quotes pp_mod),
+ ptext (sLit "To import instances alone, use:")
+ <+> ptext (sLit "import") <+> pp_mod <> parens empty ]
+ msg2 = sep [pp_herald <+> quotes (pprWithCommas ppr unused),
+ text "from module" <+> quotes pp_mod <+> pp_not_used]
+ pp_herald = text "The import of"
+ pp_mod = ppr (unLoc (ideclName decl))
+ pp_not_used = text "is redundant"
+\end{code}
+
+To print the minimal imports we walk over the user-supplied import
+decls, and simply trim their import lists. NB that
+
+ * We do *not* change the 'qualified' or 'as' parts!
+
+ * We do not disard a decl altogether; we might need instances
+ from it. Instead we just trim to an empty import list
+
+\begin{code}
+printMinimalImports :: [ImportDeclUsage] -> RnM ()
+printMinimalImports imports_w_usage
+ = do { imports' <- mapM mk_minimal imports_w_usage
+ ; this_mod <- getModule
+ ; liftIO $
+ do { h <- openFile (mkFilename this_mod) WriteMode
+ ; printForUser h neverQualify (vcat (map ppr imports')) }
+ -- The neverQualify is important. We are printing Names
+ -- but they are in the context of an 'import' decl, and
+ -- we never qualify things inside there
+ -- E.g. import Blag( f, b )
+ -- not import Blag( Blag.f, Blag.g )!
+ }
where
mkFilename this_mod = moduleNameString (moduleName this_mod) ++ ".imports"
- ppr_mod_ie (mod_name, ies)
- | mod_name == moduleName pRELUDE
- = empty
- | null ies -- Nothing except instances comes from here
- = ptext (sLit "import") <+> ppr mod_name <> ptext (sLit "() -- Instances only")
- | otherwise
- = ptext (sLit "import") <+> ppr mod_name <>
- parens (fsep (punctuate comma (map ppr ies)))
- to_ies (mod, avail_env) = do ies <- mapM to_ie (availEnvElts avail_env)
- return (mod, ies)
+ mk_minimal (L l decl, used, unused)
+ | null unused
+ , Just (False, _) <- ideclHiding decl
+ = return (L l decl)
+ | otherwise
+ = do { ies <- initIfaceTcRn $ mapM to_ie used
+ ; return (L l (decl { ideclHiding = Just (False, map (L l) ies) })) }
to_ie :: AvailInfo -> IfG (IE Name)
-- The main trick here is that if we're importing all the constructors
where
all_used avail_occs = all (`elem` map nameOccName ns) avail_occs
doc = text "Compute minimal imports from" <+> ppr n
- n_mod = nameModule n
+ n_mod = ASSERT( isExternalName n ) nameModule n
\end{code}
-
%************************************************************************
%* *
\subsection{Errors}
dodgyMsg :: OutputableBndr n => SDoc -> n -> SDoc
dodgyMsg kind tc
- = sep [ ptext (sLit "The") <+> kind <+> ptext (sLit "item") <+> quotes (ppr (IEThingAll tc)),
- ptext (sLit "suggests that") <+> quotes (ppr tc) <+> ptext (sLit "has constructors or class methods,"),
+ = sep [ ptext (sLit "The") <+> kind <+> ptext (sLit "item") <+> quotes (ppr (IEThingAll tc))
+ <+> ptext (sLit "suggests that"),
+ quotes (ppr tc) <+> ptext (sLit "has (in-scope) constructors or class methods,"),
ptext (sLit "but it has none") ]
exportItemErr :: IE RdrName -> SDoc
implicitPreludeWarn :: SDoc
implicitPreludeWarn
= ptext (sLit "Module `Prelude' implicitly imported")
+
+packageImportErr :: SDoc
+packageImportErr
+ = ptext (sLit "Package-qualified imports are not enabled; use -XPackageImports")
\end{code}
projects / ghc-hetmet.git / blobdiff