%
-% (c) The GRASP Project, Glasgow University, 1992-1996
+% (c) The GRASP Project, Glasgow University, 1992-1998
%
\section[Rename]{Renaming and dependency analysis passes}
\begin{code}
-#include "HsVersions.h"
-
module Rename ( renameModule ) where
-import Ubiq{-uitous-}
+#include "HsVersions.h"
import HsSyn
-import RdrHsSyn ( ProtoNameHsModule(..) )
-import RnHsSyn ( RenamedHsModule(..) )
-
-import Bag ( isEmptyBag, unionBags )
-import CmdLineOpts ( opt_UseGetMentionedVars )
-import ErrUtils ( Error(..) )
-import Pretty ( Pretty(..){-ToDo:rm?-} )
-import RnMonad12 ( initRn12 )
-import RnMonad4 ( initRn4 )
-import RnPass1
-import RnPass2
-import RnPass3
-import RnPass4
-import RnUtils ( PreludeNameMappers(..), GlobalNameMappers(..) )
-import UniqSupply ( splitUniqSupply )
-import Util ( panic )
+import RdrHsSyn ( RdrNameHsModule )
+import RnHsSyn ( RenamedHsModule, RenamedHsDecl, extractHsTyNames, extractHsCtxtTyNames )
+
+import CmdLineOpts ( opt_HiMap, opt_D_dump_rn_trace,
+ opt_D_dump_rn, opt_D_dump_rn_stats,
+ opt_WarnUnusedBinds, opt_WarnUnusedImports
+ )
+import RnMonad
+import RnNames ( getGlobalNames )
+import RnSource ( rnSourceDecls, rnDecl )
+import RnIfaces ( getImportedInstDecls, importDecl, getImportVersions,
+ getImportedRules, loadHomeInterface, getSlurped
+ )
+import RnEnv ( availName, availNames, availsToNameSet,
+ warnUnusedTopNames, mapFvRn,
+ FreeVars, plusFVs, plusFV, unitFV, emptyFVs, isEmptyFVs
+ )
+import Module ( Module, ModuleName, pprModule, mkSearchPath, mkThisModule )
+import Name ( Name, isLocallyDefined,
+ NamedThing(..), ImportReason(..), Provenance(..),
+ pprOccName, nameOccName,
+ getNameProvenance, occNameUserString,
+ maybeWiredInTyConName, maybeWiredInIdName, isWiredInName
+ )
+import Id ( idType )
+import DataCon ( dataConTyCon, dataConType )
+import TyCon ( TyCon, tyConDataCons, isSynTyCon, getSynTyConDefn )
+import RdrName ( RdrName )
+import NameSet
+import PrelMods ( mAIN_Name, pREL_MAIN_Name )
+import TysWiredIn ( unitTyCon, intTyCon, doubleTyCon, boolTyCon )
+import PrelInfo ( ioTyCon_NAME, thinAirIdNames )
+import Type ( namesOfType, funTyCon )
+import ErrUtils ( pprBagOfErrors, pprBagOfWarnings,
+ doIfSet, dumpIfSet, ghcExit
+ )
+import BasicTypes ( NewOrData(..) )
+import Bag ( isEmptyBag, bagToList )
+import FiniteMap ( fmToList, delListFromFM, addToFM, sizeFM, eltsFM )
+import UniqSupply ( UniqSupply )
+import Util ( equivClasses )
+import Maybes ( maybeToBool )
+import Outputable
\end{code}
-Here's what the renamer does, basically:
-\begin{description}
-\item[@RnPass1@:]
-Flattens out the declarations from the interfaces which this module
-imports. The result is a new module with no imports, but with more
-declarations. (Obviously, the imported declarations have ``funny
-names'' [@ProtoNames@] to indicate their origin.) Handles selective
-import, renaming, \& such.
-
-%--------------------------------------------------------------------
-\item[@RnPass2@:]
-Removes duplicate declarations. Duplicates can arise when two
-imported interface have a signature (or whatever) for the same
-thing. We check that the two are consistent and then drop one.
-Considerable huff and puff to pick the one with the ``better''
-pragmatic information.
-
-%--------------------------------------------------------------------
-\item[@RnPass3@:]
-Find all the top-level-ish (i.e., global) entities, assign them
-@Uniques@, and make a \tr{ProtoName -> Name} mapping for them,
-in preparation for...
-
-%--------------------------------------------------------------------
-\item[@RnPass4@:]
-Actually prepare the ``renamed'' module. In sticking @Names@ on
-everything, it will catch out-of-scope errors (and a couple of similar
-type-variable-use errors). We also our initial dependency analysis of
-the program (required before typechecking).
-\end{description}
+
\begin{code}
-renameModule :: PreludeNameMappers -- lookup funs for deeply wired-in names
- -> ProtoNameHsModule -- input
- -> UniqSupply
- -> (RenamedHsModule, -- output, after renaming
- Bag FAST_STRING, -- Names of the imported modules
- -- (profiling needs to know this)
- GlobalNameMappers, -- final name funs; used later
- -- to rename generated `deriving'
- -- bindings.
- Bag Error -- Errors, from passes 1-4
- )
-
--- Very space-leak sensitive
-
-renameModule gnfs@(val_pnf, tc_pnf)
- input@(HsModule mod_name _ _ _ _ _ _ _ _ _ _ _ _)
- uniqs
- = let
- use_mentioned_vars = opt_UseGetMentionedVars
- in
- case (initRn12 mod_name (rnModule1 gnfs use_mentioned_vars input))
- of { ((mod1, imported_module_names), errs1) ->
+renameModule :: UniqSupply
+ -> RdrNameHsModule
+ -> IO (Maybe
+ ( Module
+ , RenamedHsModule -- Output, after renaming
+ , InterfaceDetails -- Interface; for interface file generation
+ , RnNameSupply -- Final env; for renaming derivings
+ , [ModuleName] -- Imported modules; for profiling
+ ))
- case (initRn12 mod_name (rnModule2 mod1)) of { (mod2, errs2) ->
+renameModule us this_mod@(HsModule mod_name vers exports imports local_decls loc)
+ = -- Initialise the renamer monad
+ initRn mod_name us (mkSearchPath opt_HiMap) loc
+ (rename this_mod) >>=
+ \ (maybe_rn_stuff, rn_errs_bag, rn_warns_bag) ->
- case (splitUniqSupply uniqs) of { (us1, us2) ->
+ -- Check for warnings
+ doIfSet (not (isEmptyBag rn_warns_bag))
+ (printErrs (pprBagOfWarnings rn_warns_bag)) >>
- case (initRn3 (rnModule3 gnfs imported_module_names mod2) us1)
- of { (val_space, tc_space, v_gnf, tc_gnf, errs3) ->
+ -- Check for errors; exit if so
+ doIfSet (not (isEmptyBag rn_errs_bag))
+ (printErrs (pprBagOfErrors rn_errs_bag) >>
+ ghcExit 1
+ ) >>
+
+ -- Dump output, if any
+ (case maybe_rn_stuff of
+ Nothing -> return ()
+ Just results@(_, rn_mod, _, _, _)
+ -> dumpIfSet opt_D_dump_rn "Renamer:"
+ (ppr rn_mod)
+ ) >>
+
+ -- Return results
+ return maybe_rn_stuff
+\end{code}
+
+
+\begin{code}
+rename this_mod@(HsModule mod_name vers exports imports local_decls loc)
+ = -- FIND THE GLOBAL NAME ENVIRONMENT
+ getGlobalNames this_mod `thenRn` \ maybe_stuff ->
+ -- CHECK FOR EARLY EXIT
+ if not (maybeToBool maybe_stuff) then
+ -- Everything is up to date; no need to recompile further
+ rnStats [] `thenRn_`
+ returnRn Nothing
+ else
let
- final_name_funs = (v_gnf, tc_gnf)
+ Just (export_env, gbl_env, fixity_env, global_avail_env) = maybe_stuff
+ in
+
+ -- RENAME THE SOURCE
+ initRnMS gbl_env fixity_env SourceMode (
+ rnSourceDecls local_decls
+ ) `thenRn` \ (rn_local_decls, source_fvs) ->
- errs_so_far = errs1 `unionBags` errs2 `unionBags` errs3
- -- see note below about why we consult errs at this pt
+ -- SLURP IN ALL THE NEEDED DECLARATIONS
+ let
+ real_source_fvs = implicitFVs mod_name `plusFV` source_fvs
+ -- It's important to do the "plus" this way round, so that
+ -- when compiling the prelude, locally-defined (), Bool, etc
+ -- override the implicit ones.
in
- if not (isEmptyBag errs_so_far) then -- give up now
- ( panic "rename", imported_module_names, final_name_funs, errs_so_far )
+ slurpImpDecls real_source_fvs `thenRn` \ rn_imp_decls ->
+
+ -- EXIT IF ERRORS FOUND
+ checkErrsRn `thenRn` \ no_errs_so_far ->
+ if not no_errs_so_far then
+ -- Found errors already, so exit now
+ rnStats [] `thenRn_`
+ returnRn Nothing
else
- case (initRn4 final_name_funs (rnModule mod2) us2)
- of { (mod4, errs4) ->
- ( mod4, imported_module_names, final_name_funs, errs4 ) }
- }}}}
+ -- GENERATE THE VERSION/USAGE INFO
+ getImportVersions mod_name exports `thenRn` \ my_usages ->
+ getNameSupplyRn `thenRn` \ name_supply ->
+
+ -- REPORT UNUSED NAMES
+ reportUnusedNames gbl_env global_avail_env
+ export_env
+ source_fvs `thenRn_`
+
+ -- RETURN THE RENAMED MODULE
+ let
+ has_orphans = any isOrphanDecl rn_local_decls
+ direct_import_mods = [mod | ImportDecl mod _ _ _ _ _ <- imports]
+ rn_all_decls = rn_imp_decls ++ rn_local_decls
+ renamed_module = HsModule mod_name vers
+ trashed_exports trashed_imports
+ rn_all_decls
+ loc
+ in
+ rnStats rn_imp_decls `thenRn_`
+ returnRn (Just (mkThisModule mod_name,
+ renamed_module,
+ (has_orphans, my_usages, export_env),
+ name_supply,
+ direct_import_mods))
+ where
+ trashed_exports = {-trace "rnSource:trashed_exports"-} Nothing
+ trashed_imports = {-trace "rnSource:trashed_imports"-} []
+\end{code}
+
+@implicitFVs@ forces the renamer to slurp in some things which aren't
+mentioned explicitly, but which might be needed by the type checker.
+
+\begin{code}
+implicitFVs mod_name
+ = implicit_main `plusFV`
+ mkNameSet default_tys `plusFV`
+ mkNameSet thinAirIdNames
+ where
+ -- Add occurrences for Int, Double, and (), because they
+ -- are the types to which ambigious type variables may be defaulted by
+ -- the type checker; so they won't always appear explicitly.
+ -- [The () one is a GHC extension for defaulting CCall results.]
+ -- ALSO: funTyCon, since it occurs implicitly everywhere!
+ -- (we don't want to be bothered with making funTyCon a
+ -- free var at every function application!)
+ default_tys = [getName intTyCon, getName doubleTyCon,
+ getName unitTyCon, getName funTyCon, getName boolTyCon]
+
+ -- Add occurrences for IO or PrimIO
+ implicit_main | mod_name == mAIN_Name
+ || mod_name == pREL_MAIN_Name = unitFV ioTyCon_NAME
+ | otherwise = emptyFVs
\end{code}
-Why stop if errors in the first three passes: Suppose you're compiling
-a module with a top-level definition named \tr{scaleFloat}. Sadly,
-this is also a Prelude class-method name. \tr{rnModule3} will have
-detected this error, but: it will also have picked (arbitrarily) one
-of the two definitions for its final ``value'' name-function. If, by
-chance, it should have picked the class-method... when it comes to pin
-a Unique on the top-level (bogus) \tr{scaleFloat}, it will ask for the
-class-method's Unique (!); it doesn't have one, and you will get a
-panic.
-
-Another way to handle this would be for the duplicate detector to
-clobber duplicates with some ``safe'' value. Then things would be
-fine in \tr{rnModule}. Maybe some other time...
+\begin{code}
+isOrphanDecl (InstD (InstDecl inst_ty _ _ _ _))
+ = not (foldNameSet ((||) . isLocallyDefined) False (extractHsTyNames inst_ty))
+isOrphanDecl (RuleD (RuleDecl _ _ _ lhs _ _))
+ = check lhs
+ where
+ check (HsVar v) = not (isLocallyDefined v)
+ check (HsApp f a) = check f && check a
+ check other = True
+isOrphanDecl other = False
+\end{code}
+
+
+%*********************************************************
+%* *
+\subsection{Slurping declarations}
+%* *
+%*********************************************************
+
+\begin{code}
+-------------------------------------------------------
+slurpImpDecls source_fvs
+ = traceRn (text "slurpImp" <+> fsep (map ppr (nameSetToList source_fvs))) `thenRn_`
+ -- The current slurped-set records all local things
+ getSlurped `thenRn` \ local_binders ->
+
+ slurpSourceRefs source_fvs `thenRn` \ (decls1, needed1, wired_in) ->
+ let
+ inst_gates1 = foldr (plusFV . getWiredInGates) source_fvs wired_in
+ inst_gates2 = foldr (plusFV . getGates source_fvs) inst_gates1 decls1
+ in
+ -- Do this first slurpDecls before the getImportedInstDecls,
+ -- so that the home modules of all the inst_gates will be sure to be loaded
+ slurpDecls decls1 needed1 `thenRn` \ (decls2, needed2) ->
+ mapRn_ (load_home local_binders) wired_in `thenRn_`
+
+ -- Now we can get the instance decls
+ getImportedInstDecls inst_gates2 `thenRn` \ inst_decls ->
+ rnIfaceDecls decls2 needed2 inst_decls `thenRn` \ (decls3, needed3) ->
+ closeDecls decls3 needed3
+ where
+ load_home local_binders name
+ | name `elemNameSet` local_binders = returnRn ()
+ -- When compiling the prelude, a wired-in thing may
+ -- be defined in this module, in which case we don't
+ -- want to load its home module!
+ -- Using 'isLocallyDefined' doesn't work because some of
+ -- the free variables returned are simply 'listTyCon_Name',
+ -- with a system provenance. We could look them up every time
+ -- but that seems a waste.
+ | otherwise = loadHomeInterface doc name `thenRn_`
+ returnRn ()
+ where
+ doc = ptext SLIT("need home module for wired in thing") <+> ppr name
+
+-------------------------------------------------------
+slurpSourceRefs :: FreeVars -- Variables referenced in source
+ -> RnMG ([RenamedHsDecl],
+ FreeVars, -- Un-satisfied needs
+ [Name]) -- Those variables referenced in the source
+ -- that turned out to be wired in things
+
+slurpSourceRefs source_fvs
+ = go [] emptyFVs [] (nameSetToList source_fvs)
+ where
+ go decls fvs wired []
+ = returnRn (decls, fvs, wired)
+ go decls fvs wired (wanted_name:refs)
+ | isWiredInName wanted_name
+ = go decls fvs (wanted_name:wired) refs
+ | otherwise
+ = importDecl wanted_name `thenRn` \ maybe_decl ->
+ case maybe_decl of
+ -- No declaration... (already slurped, or local)
+ Nothing -> go decls fvs wired refs
+ Just decl -> rnIfaceDecl decl `thenRn` \ (new_decl, fvs1) ->
+ go (new_decl : decls) (fvs1 `plusFV` fvs) wired
+ (extraGates new_decl ++ refs)
+
+-- Hack alert. If we suck in a class
+-- class Ord a => Baz a where ...
+-- then Eq is also a 'gate'. Why? Because Eq is a superclass of Ord,
+-- and hence may be needed during context reduction even though
+-- Eq is never mentioned explicitly. So we snaffle out the super-classes
+-- right now, so that slurpSourceRefs will heave them in
+--
+-- Similarly the RHS of type synonyms
+extraGates (TyClD (ClassDecl ctxt _ tvs _ _ _ _ _ _ _))
+ = nameSetToList (delListFromNameSet (extractHsCtxtTyNames ctxt) (map getTyVarName tvs))
+extraGates (TyClD (TySynonym _ tvs ty _))
+ = nameSetToList (delListFromNameSet (extractHsTyNames ty) (map getTyVarName tvs))
+extraGates other = []
+
+-------------------------------------------------------
+-- closeDecls keeps going until the free-var set is empty
+closeDecls decls needed
+ | not (isEmptyFVs needed)
+ = slurpDecls decls needed `thenRn` \ (decls1, needed1) ->
+ closeDecls decls1 needed1
+
+ | otherwise
+ = getImportedRules `thenRn` \ rule_decls ->
+ case rule_decls of
+ [] -> returnRn decls -- No new rules, so we are done
+ other -> rnIfaceDecls decls emptyFVs rule_decls `thenRn` \ (decls1, needed1) ->
+ closeDecls decls1 needed1
+
+
+-------------------------------------------------------
+rnIfaceDecls :: [RenamedHsDecl] -> FreeVars
+ -> [(Module, RdrNameHsDecl)]
+ -> RnM d ([RenamedHsDecl], FreeVars)
+rnIfaceDecls decls fvs [] = returnRn (decls, fvs)
+rnIfaceDecls decls fvs (d:ds) = rnIfaceDecl d `thenRn` \ (new_decl, fvs1) ->
+ rnIfaceDecls (new_decl:decls) (fvs1 `plusFV` fvs) ds
+
+rnIfaceDecl (mod, decl) = initIfaceRnMS mod (rnDecl decl)
+
+
+-------------------------------------------------------
+-- Augment decls with any decls needed by needed.
+-- Return also free vars of the new decls (only)
+slurpDecls decls needed
+ = go decls emptyFVs (nameSetToList needed)
+ where
+ go decls fvs [] = returnRn (decls, fvs)
+ go decls fvs (ref:refs) = slurpDecl decls fvs ref `thenRn` \ (decls1, fvs1) ->
+ go decls1 fvs1 refs
+
+-------------------------------------------------------
+slurpDecl decls fvs wanted_name
+ = importDecl wanted_name `thenRn` \ maybe_decl ->
+ case maybe_decl of
+ -- No declaration... (wired in thing)
+ Nothing -> returnRn (decls, fvs)
+
+ -- Found a declaration... rename it
+ Just decl -> rnIfaceDecl decl `thenRn` \ (new_decl, fvs1) ->
+ returnRn (new_decl:decls, fvs1 `plusFV` fvs)
+\end{code}
+
+
+%*********************************************************
+%* *
+\subsection{Extracting the 'gates'}
+%* *
+%*********************************************************
+
+When we import a declaration like
+
+ data T = T1 Wibble | T2 Wobble
+
+we don't want to treat Wibble and Wobble as gates *unless* T1, T2
+respectively are mentioned by the user program. If only T is mentioned
+we want only T to be a gate; that way we don't suck in useless instance
+decls for (say) Eq Wibble, when they can't possibly be useful.
+
+@getGates@ takes a newly imported (and renamed) decl, and the free
+vars of the source program, and extracts from the decl the gate names.
+
+\begin{code}
+getGates source_fvs (SigD (IfaceSig _ ty _ _))
+ = extractHsTyNames ty
+
+getGates source_fvs (TyClD (ClassDecl ctxt cls tvs sigs _ _ _ _ _ _))
+ = delListFromNameSet (foldr (plusFV . get) (extractHsCtxtTyNames ctxt) sigs)
+ (map getTyVarName tvs)
+ `addOneToNameSet` cls
+ where
+ get (ClassOpSig n _ ty _)
+ | n `elemNameSet` source_fvs = extractHsTyNames ty
+ | otherwise = emptyFVs
+
+getGates source_fvs (TyClD (TySynonym tycon tvs ty _))
+ = delListFromNameSet (extractHsTyNames ty)
+ (map getTyVarName tvs)
+ `addOneToNameSet` tycon
+
+getGates source_fvs (TyClD (TyData _ ctxt tycon tvs cons _ _ _))
+ = delListFromNameSet (foldr (plusFV . get) (extractHsCtxtTyNames ctxt) cons)
+ (map getTyVarName tvs)
+ `addOneToNameSet` tycon
+ where
+ get (ConDecl n tvs ctxt details _)
+ | n `elemNameSet` source_fvs
+ -- If the constructor is method, get fvs from all its fields
+ = delListFromNameSet (get_details details `plusFV`
+ extractHsCtxtTyNames ctxt)
+ (map getTyVarName tvs)
+ get (ConDecl n tvs ctxt (RecCon fields) _)
+ -- Even if the constructor isn't mentioned, the fields
+ -- might be, as selectors. They can't mention existentially
+ -- bound tyvars (typechecker checks for that) so no need for
+ -- the deleteListFromNameSet part
+ = foldr (plusFV . get_field) emptyFVs fields
+
+ get other_con = emptyFVs
+
+ get_details (VanillaCon tys) = plusFVs (map get_bang tys)
+ get_details (InfixCon t1 t2) = get_bang t1 `plusFV` get_bang t2
+ get_details (RecCon fields) = plusFVs [get_bang t | (_, t) <- fields]
+ get_details (NewCon t _) = extractHsTyNames t
+
+ get_field (fs,t) | any (`elemNameSet` source_fvs) fs = get_bang t
+ | otherwise = emptyFVs
+
+ get_bang (Banged t) = extractHsTyNames t
+ get_bang (Unbanged t) = extractHsTyNames t
+ get_bang (Unpacked t) = extractHsTyNames t
+
+getGates source_fvs other_decl = emptyFVs
+\end{code}
+
+getWiredInGates is just like getGates, but it sees a wired-in Name
+rather than a declaration.
+
+\begin{code}
+getWiredInGates name | is_tycon = get_wired_tycon the_tycon
+ | otherwise = get_wired_id the_id
+ where
+ maybe_wired_in_tycon = maybeWiredInTyConName name
+ is_tycon = maybeToBool maybe_wired_in_tycon
+ maybe_wired_in_id = maybeWiredInIdName name
+ Just the_tycon = maybe_wired_in_tycon
+ Just the_id = maybe_wired_in_id
+
+get_wired_id id = namesOfType (idType id)
+
+get_wired_tycon tycon
+ | isSynTyCon tycon
+ = namesOfType ty `minusNameSet` mkNameSet (map getName tyvars)
+
+ | otherwise -- data or newtype
+ = foldr (unionNameSets . namesOfType . dataConType) emptyNameSet data_cons
+ where
+ (tyvars,ty) = getSynTyConDefn tycon
+ data_cons = tyConDataCons tycon
+\end{code}
+
+
+%*********************************************************
+%* *
+\subsection{Unused names}
+%* *
+%*********************************************************
+
+\begin{code}
+reportUnusedNames gbl_env avail_env (ExportEnv export_avails _) mentioned_names
+ | not (opt_WarnUnusedBinds || opt_WarnUnusedImports)
+ = returnRn ()
+
+ | otherwise
+ = let
+ used_names = mentioned_names `unionNameSets` availsToNameSet export_avails
+
+ -- Now, a use of C implies a use of T,
+ -- if C was brought into scope by T(..) or T(C)
+ really_used_names = used_names `unionNameSets`
+ mkNameSet [ availName avail
+ | sub_name <- nameSetToList used_names,
+ let avail = case lookupNameEnv avail_env sub_name of
+ Just avail -> avail
+ Nothing -> pprTrace "r.u.n" (ppr sub_name) $
+ Avail sub_name
+ ]
+
+ defined_names = mkNameSet (concat (rdrEnvElts gbl_env))
+ defined_but_not_used = nameSetToList (defined_names `minusNameSet` really_used_names)
+
+ -- Filter out the ones only defined implicitly
+ bad_guys = filter reportableUnusedName defined_but_not_used
+ in
+ warnUnusedTopNames bad_guys `thenRn_`
+ returnRn ()
+
+reportableUnusedName :: Name -> Bool
+reportableUnusedName name
+ = explicitlyImported (getNameProvenance name) &&
+ not (startsWithUnderscore (occNameUserString (nameOccName name)))
+ where
+ explicitlyImported (LocalDef _ _) = True -- Report unused defns of local vars
+ explicitlyImported (NonLocalDef (UserImport _ _ expl) _) = expl -- Report unused explicit imports
+ explicitlyImported other = False -- Don't report others
+
+ -- Haskell 98 encourages compilers to suppress warnings about
+ -- unused names in a pattern if they start with "_".
+ startsWithUnderscore ('_' : _) = True -- Suppress warnings for names starting
+ startsWithUnderscore other = False -- with an underscore
+
+rnStats :: [RenamedHsDecl] -> RnMG ()
+rnStats imp_decls
+ | opt_D_dump_rn_trace ||
+ opt_D_dump_rn_stats ||
+ opt_D_dump_rn
+ = getRnStats imp_decls `thenRn` \ msg ->
+ ioToRnM (printErrs msg) `thenRn_`
+ returnRn ()
+
+ | otherwise = returnRn ()
+\end{code}
+
+
+
+%*********************************************************
+%* *
+\subsection{Statistics}
+%* *
+%*********************************************************
+
+\begin{code}
+getRnStats :: [RenamedHsDecl] -> RnMG SDoc
+getRnStats imported_decls
+ = getIfacesRn `thenRn` \ ifaces ->
+ let
+ n_mods = length [() | (_, _, Just _) <- eltsFM (iImpModInfo ifaces)]
+
+ decls_read = [decl | (_, avail, True, (_,decl)) <- nameEnvElts (iDecls ifaces),
+ -- Data, newtype, and class decls are in the decls_fm
+ -- under multiple names; the tycon/class, and each
+ -- constructor/class op too.
+ -- The 'True' selects just the 'main' decl
+ not (isLocallyDefined (availName avail))
+ ]
+
+ (cd_rd, dd_rd, nd_rd, sd_rd, vd_rd, _) = count_decls decls_read
+ (cd_sp, dd_sp, nd_sp, sd_sp, vd_sp, id_sp) = count_decls imported_decls
+
+ unslurped_insts = iInsts ifaces
+ inst_decls_unslurped = length (bagToList unslurped_insts)
+ inst_decls_read = id_sp + inst_decls_unslurped
+
+ stats = vcat
+ [int n_mods <+> text "interfaces read",
+ hsep [ int cd_sp, text "class decls imported, out of",
+ int cd_rd, text "read"],
+ hsep [ int dd_sp, text "data decls imported, out of",
+ int dd_rd, text "read"],
+ hsep [ int nd_sp, text "newtype decls imported, out of",
+ int nd_rd, text "read"],
+ hsep [int sd_sp, text "type synonym decls imported, out of",
+ int sd_rd, text "read"],
+ hsep [int vd_sp, text "value signatures imported, out of",
+ int vd_rd, text "read"],
+ hsep [int id_sp, text "instance decls imported, out of",
+ int inst_decls_read, text "read"],
+ text "cls dcls slurp" <+> fsep (map (ppr . tyClDeclName)
+ [d | TyClD d <- imported_decls, isClassDecl d]),
+ text "cls dcls read" <+> fsep (map (ppr . tyClDeclName)
+ [d | TyClD d <- decls_read, isClassDecl d])]
+ in
+ returnRn (hcat [text "Renamer stats: ", stats])
+
+count_decls decls
+ = (class_decls,
+ data_decls,
+ newtype_decls,
+ syn_decls,
+ val_decls,
+ inst_decls)
+ where
+ tycl_decls = [d | TyClD d <- decls]
+ (class_decls, data_decls, newtype_decls, syn_decls) = countTyClDecls tycl_decls
+
+ val_decls = length [() | SigD _ <- decls]
+ inst_decls = length [() | InstD _ <- decls]
+\end{code}
+