RnIfaces.lhs 29.5 KB
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%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
%
\section[RnIfaces]{Cacheing and Renaming of Interfaces}

\begin{code}
#include "HsVersions.h"

module RnIfaces (
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	findHiFiles,
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	cachedIface,
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	cachedDecl,
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	readIface,
	rnIfaces,
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	IfaceCache(..)
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    ) where

import Ubiq

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import LibDirectory
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import PreludeGlaST	( thenPrimIO, seqPrimIO, readVar, writeVar, MutableVar(..) )
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import HsSyn
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import HsPragmas	( noGenPragmas )
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import RdrHsSyn
import RnHsSyn

import RnMonad
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import RnSource		( rnTyDecl, rnClassDecl, rnInstDecl, rnPolyType )
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import RnUtils		( RnEnv(..), emptyRnEnv, lookupRnEnv, lookupTcRnEnv, extendGlobalRnEnv )
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import ParseIface	( parseIface )
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import ParseUtils	( ParsedIface(..), RdrIfaceDecl(..), RdrIfaceInst(..),
			  VersionsMap(..), UsagesMap(..)
			)
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import Bag		( emptyBag, unitBag, consBag, snocBag,
			  unionBags, unionManyBags, isEmptyBag, bagToList )
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import CmdLineOpts	( opt_HiSuffix, opt_SysHiSuffix )
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import ErrUtils		( Error(..), Warning(..) )
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import FiniteMap	( emptyFM, lookupFM, addToFM, addToFM_C, plusFM, eltsFM,
			  fmToList, delListFromFM, sizeFM, foldFM, unitFM,
			  plusFM_C, keysFM{-ToDo:rm-}
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			)
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import Maybes		( maybeToBool )
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import Name		( moduleNamePair, origName, isRdrLexCon, RdrName(..) )
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import PprStyle		-- ToDo:rm
import Outputable	-- ToDo:rm
import PrelInfo		( builtinNameInfo )
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import Pretty
import Maybes		( MaybeErr(..) )
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import UniqFM		( emptyUFM )
import UniqSupply	( splitUniqSupply )
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import Util		( sortLt, removeDups, cmpPString, startsWith,
			  panic, pprPanic, assertPanic, pprTrace{-ToDo:rm-} )
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\end{code}

\begin{code}
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type ModuleToIfaceContents = FiniteMap Module ParsedIface
type ModuleToIfaceFilePath = FiniteMap Module FilePath
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type IfaceCache
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  = MutableVar _RealWorld
	(ModuleToIfaceContents,	-- interfaces for individual interface files
	 ModuleToIfaceContents, -- merged interfaces based on module name
				-- used for extracting info about original names
	 ModuleToIfaceFilePath)
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\end{code}

*********************************************************
*							*
\subsection{Looking for interface files}
*							*
*********************************************************

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Return a mapping from module-name to
absolute-filename-for-that-interface.
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\begin{code}
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findHiFiles :: [FilePath] -> [FilePath] -> IO (FiniteMap Module FilePath)

findHiFiles dirs sysdirs
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  = --hPutStr stderr "  findHiFiles "	>>
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    do_dirs emptyFM (dirs ++ sysdirs)	>>= \ result ->
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    --hPutStr stderr " done\n"		>>
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    return result
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  where
    do_dirs env [] = return env
    do_dirs env (dir:dirs)
      = do_dir  env     dir	>>= \ new_env ->
	do_dirs new_env dirs
    -------
    do_dir env dir
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      = --hPutStr stderr "D" >>
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	getDirectoryContents dir    >>= \ entries ->
	do_entries env entries
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      where
	do_entries env [] = return env
	do_entries env (e:es)
	  = do_entry   env     e    >>= \ new_env ->
	    do_entries new_env es
	-------
	do_entry env e
	  = case (acceptable_hi (reverse e)) of
	      Nothing  -> --trace ("Deemed uncool:"++e) $
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			  --hPutStr stderr "." >>
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			  return env
	      Just mod ->
		let
		      pmod = _PK_ mod
		in
		case (lookupFM env pmod) of
		  Nothing -> --trace ("Adding "++mod++" -> "++e) $
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			     --hPutStr stderr "!" >>
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			     return (addToFM env pmod (dir ++ '/':e))
			     -- ToDo: use DIR_SEP, not /

		  Just xx -> ( if de_dot xx /= e then trace ("Already mapped!! "++mod++" -> "++xx++"; ignoring:"++e) else id) $
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			     --hPutStr stderr "." >>
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			     return env
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    -------
    acceptable_hi rev_e -- looking at pathname *backwards*
      = case (startsWith (reverse opt_HiSuffix) rev_e) of
	  Nothing -> Nothing
	  Just xs -> plausible_modname xs{-reversed-}

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    -------
    de_dot ('.' : '/' : xs) = xs
    de_dot xs		    = xs

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    -------
    plausible_modname rev_e
      = let
	    cand = reverse (takeWhile is_modname_char rev_e)
	in
	if null cand || not (isUpper (head cand))
	then Nothing
	else Just cand
      where
	is_modname_char c = isAlphanum c || c == '_'
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\end{code}
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*********************************************************
*							*
\subsection{Reading interface files}
*							*
*********************************************************
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Return cached info about a Module's interface; otherwise,
read the interface (using our @ModuleToIfaceFilePath@ map
to decide where to look).

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Note: we have two notions of interface
 * the interface for a particular file name
 * the (combined) interface for a particular module name

The idea is that two source files may declare a module
with the same name with the declarations being merged.

This allows us to have file PreludeList.hs producing
PreludeList.hi but defining part of module Prelude.
When PreludeList is imported its contents will be
added to Prelude. In this way all the original names 
for a particular module will be available the imported
decls are renamed.

ToDo: Check duplicate definitons are the same.
ToDo: Check/Merge duplicate pragmas.


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\begin{code}
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cachedIface :: Bool		-- True  => want merged interface for original name
	    -> IfaceCache	-- False => want file interface only
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	    -> Module
	    -> IO (MaybeErr ParsedIface Error)
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cachedIface want_orig_iface iface_cache mod
  = readVar iface_cache `thenPrimIO` \ (iface_fm, orig_fm, file_fm) ->
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    case (lookupFM iface_fm mod) of
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      Just iface -> return (want_iface iface orig_fm)
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      Nothing    ->
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      	case (lookupFM file_fm mod) of
	  Nothing   -> return (Failed (noIfaceErr mod))
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	  Just file ->
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	    readIface file mod >>= \ read_iface ->
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	    case read_iface of
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	      Failed err      -> -- pprTrace "module-file map:\n" (ppAboves [ppCat [ppPStr m, ppStr f] | (m,f) <- fmToList file_fm]) $
				 return (Failed err)
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	      Succeeded iface ->
		let
		    iface_fm' = addToFM iface_fm mod iface
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		    orig_fm'  = addToFM_C mergeIfaces orig_fm (iface_mod iface) iface
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		in
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		writeVar iface_cache (iface_fm', orig_fm', file_fm) `seqPrimIO`
		return (want_iface iface orig_fm')
  where
    want_iface iface orig_fm 
      | want_orig_iface
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      = case lookupFM orig_fm mod of
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	  Nothing         -> Failed (noOrigIfaceErr mod)
          Just orig_iface -> Succeeded orig_iface
      | otherwise
      = Succeeded iface

    iface_mod (ParsedIface mod _ _ _ _ _ _ _ _ _ _ _ _) = mod

----------
mergeIfaces (ParsedIface mod1 (_, files1) _ _ _ _ _ _ fixes1 tdefs1 vdefs1 idefs1 prags1)
	    (ParsedIface mod2 (_, files2) _ _ _ _ _ _ fixes2 tdefs2 vdefs2 idefs2 prags2)
  = pprTrace "mergeIfaces:" (ppCat [ppStr "import", ppCat (map ppPStr (bagToList files2)),
				    ppStr "merged with", ppPStr mod1]) $
    ASSERT(mod1 == mod2)
    ParsedIface mod1
	(True, unionBags files1 files2)
	(panic "mergeIface: module version numbers")
	(panic "mergeIface: source version numbers")	-- Version numbers etc must be extracted from
	(panic "mergeIface: usage version numbers")	-- the merged file interfaces named above
	(panic "mergeIface: decl version numbers")
	(panic "mergeIface: exports")
	(panic "mergeIface: instance modules")
 	(plusFM_C (dup_merge "fixity"      (ppr PprDebug . fixDeclName)) fixes1 fixes2)
	(plusFM_C (dup_merge "tycon/class" (ppr PprDebug . idecl_nm))    tdefs1 tdefs2)
	(plusFM_C (dup_merge "value"       (ppr PprDebug . idecl_nm))    vdefs1 vdefs2)
	(unionBags idefs1 idefs2)
	(plusFM_C (dup_merge "pragma"      ppStr)			 prags1 prags2)
  where
    dup_merge str ppr_dup dup1 dup2
      = pprTrace "mergeIfaces:"
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	   	 (ppCat [ppPStr mod1, ppPStr mod2, ppStr ": dup", ppStr str, ppStr "decl",
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			 ppr_dup dup1, ppr_dup dup2]) $
        dup2

    idecl_nm (TypeSig    n _ _)     = n
    idecl_nm (NewTypeSig n _ _ _)   = n
    idecl_nm (DataSig    n _ _ _ _) = n
    idecl_nm (ClassSig   n _ _ _)   = n
    idecl_nm (ValSig     n _ _)	    = n
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----------
cachedDecl :: IfaceCache
	   -> Bool	-- True <=> tycon or class name
	   -> RdrName
	   -> IO (MaybeErr RdrIfaceDecl Error)

cachedDecl iface_cache class_or_tycon orig 
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  = cachedIface True iface_cache mod 	>>= \ maybe_iface ->
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    case maybe_iface of
      Failed err -> return (Failed err)
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      Succeeded (ParsedIface _ _ _ _ _ _ exps _ _ tdefs vdefs _ _) -> 
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	case (lookupFM (if class_or_tycon then tdefs else vdefs) str) of
	  Just decl -> return (Succeeded decl)
	  Nothing   -> return (Failed (noDeclInIfaceErr mod str))
  where
    (mod, str) = moduleNamePair orig

----------
cachedDeclByType :: IfaceCache
		 -> RnName{-NB: diff type than cachedDecl -}
		 -> IO (MaybeErr RdrIfaceDecl Error)

cachedDeclByType iface_cache rn
    -- the idea is: check that, e.g., if we're given an
    -- RnClass, then we really get back a ClassDecl from
    -- the cache (not an RnData, or something silly)
  = cachedDecl iface_cache (isRnTyConOrClass rn) (origName rn)  >>= \ maybe_decl ->
    let
	return_maybe_decl = return maybe_decl
	return_failed msg = return (Failed msg)
    in
    case maybe_decl of
      Failed _ -> return_maybe_decl
      Succeeded if_decl ->
	case rn of
	  WiredInId _       -> return_failed (ifaceLookupWiredErr "value" rn)
	  WiredInTyCon _    -> return_failed (ifaceLookupWiredErr "type constructor" rn)
	  RnUnbound _       -> pprPanic "cachedDeclByType:" (ppr PprDebug rn)
	  
	  RnSyn _	    -> return_maybe_decl
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	  RnData _ _ _	    -> return_maybe_decl
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	  RnImplicitTyCon _ -> if is_tycon_decl if_decl
			       then return_maybe_decl
			       else return_failed (badIfaceLookupErr "type constructor" rn if_decl)
	  
	  RnClass _ _	    -> return_maybe_decl
	  RnImplicitClass _ -> if is_class_decl if_decl
			       then return_maybe_decl
			       else return_failed (badIfaceLookupErr "class" rn if_decl)
	  
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	  RnName _	    -> return_maybe_decl
	  RnConstr _ _      -> return_maybe_decl
	  RnField _ _ 	    -> return_maybe_decl
	  RnClassOp _ _	    -> return_maybe_decl
	  RnImplicit _	    -> if is_val_decl if_decl
			       then return_maybe_decl
			       else return_failed (badIfaceLookupErr "value" rn if_decl)
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  where
    is_tycon_decl (TypeSig _ _ _)	= True
    is_tycon_decl (NewTypeSig _ _ _ _)	= True
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    is_tycon_decl (DataSig _ _ _ _ _)	= True
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    is_tycon_decl _			= False

    is_class_decl (ClassSig _ _ _ _)	= True
    is_class_decl _			= False

    is_val_decl (ValSig _ _ _)		= True
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    is_val_decl (DataSig _ _ _ _ _)	= True	-- may be a constr or field
    is_val_decl (NewTypeSig _ _ _ _)	= True  -- may be a constr
    is_val_decl (ClassSig _ _ _ _)	= True	-- may be a method
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    is_val_decl _			= False
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\end{code}
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\begin{code}
readIface :: FilePath -> Module
	      -> IO (MaybeErr ParsedIface Error)

readIface file mod
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  = --hPutStr stderr ("  reading "++file)	>>
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    readFile file		`thenPrimIO` \ read_result ->
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    case read_result of
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      Left  err      -> return (Failed (cannaeReadErr file err))
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      Right contents -> --hPutStr stderr " parsing"   >>
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			let parsed = parseIface contents in
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			--hPutStr stderr " done\n"    >>
			return (
			case parsed of
			  Failed _    -> parsed
			  Succeeded p -> Succeeded (init_merge mod p)
			)
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  where
    init_merge this (ParsedIface mod _ v sv us vs exps insts fixes tdefs vdefs idefs prags)
      =	ParsedIface mod (False, unitBag this) v sv us vs exps insts fixes tdefs vdefs idefs prags
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\end{code}


\begin{code}
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rnIfaces :: IfaceCache			-- iface cache (mutvar)
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	 -> [Module]			-- directly imported modules
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	 -> UniqSupply
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	 -> RnEnv			-- defined (in the source) name env
	 -> RnEnv			-- mentioned (in the source) name env 
	 -> RenamedHsModule		-- module to extend with iface decls
	 -> [RnName]			-- imported names required (really the
					-- same info as in mentioned name env)
					-- Also, all the things we may look up
					-- later by key (Unique).
	 -> IO (RenamedHsModule,	-- extended module
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		RnEnv,			-- final env (for renaming derivings)
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		ImplicitEnv,		-- implicit names used (for usage info)
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		(UsagesMap,VersionsMap,[Module]),	-- usage info
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		(Bag Error, Bag Warning))
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rnIfaces iface_cache imp_mods us
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	 def_env@((dqual, dunqual, dtc_qual, dtc_unqual), dstack)
	 occ_env@((qual, unqual, tc_qual, tc_unqual), stack)
	 rn_module@(HsModule modname iface_version exports imports fixities
		      typedecls typesigs classdecls instdecls instsigs
		      defdecls binds sigs src_loc)
	 todo
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  = {-
    pprTrace "rnIfaces:going after:" (ppCat (map (ppr PprDebug) todo)) $
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    pprTrace "rnIfaces:qual:"      (ppCat [ppBesides[ppPStr m,ppChar '.',ppPStr n] | (n,m) <- keysFM qual]) $
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    pprTrace "rnIfaces:unqual:"    (ppCat (map ppPStr (keysFM unqual))) $
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    pprTrace "rnIfaces:tc_qual:"   (ppCat [ppBesides[ppPStr m,ppChar '.',ppPStr n] | (n,m) <- keysFM tc_qual]) $
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    pprTrace "rnIfaces:tc_unqual:" (ppCat (map ppPStr (keysFM tc_unqual))) $

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    pprTrace "rnIfaces:dqual:"     (ppCat [ppBesides[ppPStr m,ppChar '.',ppPStr n] | (n,m) <- keysFM dqual]) $
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    pprTrace "rnIfaces:dunqual:"   (ppCat (map ppPStr (keysFM dunqual))) $
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    pprTrace "rnIfaces:dtc_qual:"  (ppCat [ppBesides[ppPStr m,ppChar '.',ppPStr n] | (n,m) <- keysFM dtc_qual]) $
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    pprTrace "rnIfaces:dtc_unqual:"(ppCat (map ppPStr (keysFM dtc_unqual))) $
    -}

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    -- do transitive closure to bring in all needed names/defns and insts:
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    decls_and_insts todo def_env occ_env empty_return us 
	>>= \ (((if_typedecls, if_classdecls, if_instdecls, if_sigs),
	        if_implicits,
	        if_errs_warns),
	       if_final_env) ->
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    -- finalize what we want to say we learned about the
    -- things we used
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    finalIfaceInfo iface_cache modname if_final_env if_instdecls {-all_imports_used imp_mods-} >>=
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	\ usage_stuff@(usage_info, version_info, instance_mods) ->

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    return (HsModule modname iface_version exports imports fixities
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		 (typedecls ++ if_typedecls)
		 typesigs
		 (classdecls ++ if_classdecls)
		 (instdecls  ++ if_instdecls)
		 instsigs defdecls binds
		 (sigs ++ if_sigs)
		 src_loc,
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	    if_final_env,
	    if_implicits,
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	    usage_stuff,
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	    if_errs_warns)
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  where
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    decls_and_insts todo def_env occ_env to_return us
      =	do_decls todo	     		 -- initial batch of names to process
	 	 (def_env, occ_env, us1) -- init stuff down
	 	 to_return		 -- acc results
	   >>= \ (decls_return,
		  decls_def_env,
		  decls_occ_env) ->

	cacheInstModules iface_cache imp_mods >>= \ errs ->

	do_insts decls_def_env decls_occ_env emptyRnEnv emptyFM
		 (add_errs errs decls_return) us2
      where
	(us1,us2) = splitUniqSupply us

    do_insts def_env occ_env prev_env done_insts to_return us
      | size_tc_env occ_env == size_tc_env prev_env
      = return (to_return, occ_env)

      | otherwise
      = rnIfaceInstStuff iface_cache modname us1 occ_env done_insts to_return
	   >>= \ (insts_return,
		  new_insts,
		  insts_occ_env,
		  new_unknowns) ->

	do_decls new_unknowns	  		-- new batch of names to process
	 	 (def_env, insts_occ_env, us2) 	-- init stuff down
	 	 insts_return		 	-- acc results
	   >>= \ (decls_return,
		  decls_def_env,
		  decls_occ_env) ->

	do_insts decls_def_env decls_occ_env occ_env new_insts decls_return us3
      where
	(us1,us') = splitUniqSupply us
	(us2,us3) = splitUniqSupply us'

	size_tc_env ((_, _, qual, unqual), _)
	  = sizeFM qual + sizeFM unqual
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    do_decls :: [RnName]	-- Names we're looking for; we keep adding/deleting
			  	-- from this list; we're done when empty (nothing
			  	-- more needs to be looked for)
	     -> Go_Down	 	-- see defn below
	     -> To_Return	-- accumulated result
	     -> IO (To_Return,
		    RnEnv,	-- extended decl env
		    RnEnv)	-- extended occ env

    do_decls to_find@[] down to_return
      = return (to_return, defenv down, occenv down)

    do_decls to_find@(n:ns) down to_return 
      = case (lookup_defd down n) of
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	  Just  _ -> -- previous processing must've found the stuff for this name;
		     -- continue with the rest:
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		     -- pprTrace "do_decls:done:" (ppr PprDebug n) $
		     do_decls ns down to_return
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	  Nothing
	   | fst (moduleNamePair n) == modname ->
		     -- avoid looking in interface for the module being compiled
		     -- pprTrace "do_decls:this module error:" (ppr PprDebug n) $
		     do_decls ns down (add_err (thisModImplicitErr modname n) to_return)
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	   | otherwise ->
		     -- OK, see what the cache has for us...
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	     cachedDeclByType iface_cache n >>= \ maybe_ans ->
	     case maybe_ans of
	       Failed err -> -- add the error, but keep going:
			     -- pprTrace "do_decls:cache error:" (ppr PprDebug n) $
			     do_decls ns down (add_err err to_return)

	       Succeeded iface_decl -> -- something needing renaming!
		 let
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		    (us1, us2) = splitUniqSupply (uniqsupply down)
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		 in
		 case (initRn False{-iface-} modname (occenv down) us1 (
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			setExtraRn emptyUFM{-no fixities-} $
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			rnIfaceDecl iface_decl)) of {
		  ((if_decl, if_defd, if_implicits), if_errs, if_warns) ->
		    let
			new_unknowns = eltsFM (fst if_implicits) ++ eltsFM (snd if_implicits)
		    in
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		    {-
		    pprTrace "do_decls:renamed:" (ppAboves [ppr PprDebug n
			, ppCat [ppStr "new unknowns:", interpp'SP PprDebug new_unknowns]
			, ppCat [ppStr "defd vals:", interpp'SP PprDebug [n | (_,n) <- fst if_defd] ]
			, ppCat [ppStr "defd  tcs:", interpp'SP PprDebug [n | (_,n) <- snd if_defd] ]
			]) $
		    -}
		    do_decls (new_unknowns ++ ns)
			     (add_occs       if_defd if_implicits $
			       new_uniqsupply us2 down)
			     (add_decl	     if_decl		$
			       add_implicits if_implicits	$
			        add_errs     if_errs		$
			         add_warns   if_warns to_return)
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	         }
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-----------
type Go_Down   = (RnEnv,	-- stuff we already have defns for;
				-- to check quickly if we've already
				-- found something for the name under consideration,
			  	-- due to previous processing.
				-- It starts off just w/ the defns for
				-- the things in this module.
		  RnEnv,	-- occurrence env; this gets added to as
				-- we process new iface decls.  It includes
				-- entries for *all* occurrences, including those
				-- for which we have definitions.
		  UniqSupply	-- the obvious
		 )

lookup_defd (def_env, _, _) n
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  | isRnTyConOrClass n 
  = lookupTcRnEnv def_env (origName n)
  | otherwise 
  = lookupRnEnv def_env (origName n)
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defenv	   (def_env, _, _) = def_env
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occenv	   (_, occ_env, _) = occ_env
uniqsupply (_, _,      us) = us

new_uniqsupply us (def_env, occ_env, _) = (def_env, occ_env, us)

add_occs (val_defds, tc_defds) (val_imps, tc_imps) (def_env, occ_env, us)
  = case (extendGlobalRnEnv def_env val_defds tc_defds) of { (new_def_env, def_dups) ->
    ASSERT(isEmptyBag def_dups)
    let
	val_occs = val_defds ++ fmToList val_imps
	tc_occs  = tc_defds  ++ fmToList tc_imps
    in
    case (extendGlobalRnEnv occ_env val_occs tc_occs)   of { (new_occ_env, occ_dups) ->

--  ASSERT(isEmptyBag occ_dups)
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--  False because we may get a dup on the name we just shoved in
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    (new_def_env, new_occ_env, us) }}

----------------
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type To_Return = (([RenamedTyDecl], [RenamedClassDecl], [RenamedInstDecl], [RenamedSig]),
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		  ImplicitEnv,	-- new names used implicitly
		  (Bag Error, Bag Warning)
		 )

empty_return :: To_Return
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empty_return = (([],[],[],[]), emptyImplicitEnv, (emptyBag,emptyBag))
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add_decl decl ((tydecls, classdecls, instdecls, sigs), implicit, msgs)
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  = case decl of
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      AddedTy	 t -> ((t:tydecls, classdecls, instdecls, sigs), implicit, msgs)
      AddedClass c -> ((tydecls, c:classdecls, instdecls, sigs), implicit, msgs)
      AddedSig	 s -> ((tydecls, classdecls, instdecls, s:sigs), implicit, msgs)

add_insts is ((tydecls, classdecls, instdecls, sigs), implicit, msgs)
  = ((tydecls, classdecls, is ++ instdecls, sigs), implicit, msgs)
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add_implicits (val_imps, tc_imps) (decls, (val_fm, tc_fm), msgs)
  = (decls, (val_fm `plusFM` val_imps, tc_fm `plusFM`  tc_imps), msgs)

add_err  err (decls,implicit,(errs,warns)) = (decls,implicit,(errs `snocBag`   err,warns))
add_errs ers (decls,implicit,(errs,warns)) = (decls,implicit,(errs `unionBags` ers,warns))
add_warns ws (decls,implicit,(errs,warns)) = (decls,implicit,(errs, warns `unionBags` ws))
\end{code}

\begin{code}
data AddedDecl -- purely local
  = AddedTy	RenamedTyDecl
  | AddedClass	RenamedClassDecl
  | AddedSig	RenamedSig

rnIfaceDecl :: RdrIfaceDecl
	    -> RnM_Fixes _RealWorld
		   (AddedDecl,	-- the resulting decl to add to the pot
		    ([(RdrName,RnName)], [(RdrName,RnName)]),
				-- new val/tycon-class names that have
				-- *been defined* while processing this decl
		    ImplicitEnv -- new implicit val/tycon-class names that we
				-- stumbled into
		   )

rnIfaceDecl (TypeSig tc _ decl)
  = rnTyDecl    decl	`thenRn` \ rn_decl   ->
    lookupTyCon tc	`thenRn` \ rn_tc     ->
    getImplicitUpRn	`thenRn` \ mentioned ->
    let
	defds = ([], [(tc, rn_tc)])
	implicits = mentioned `sub` defds
    in
    returnRn (AddedTy rn_decl, defds, implicits)

rnIfaceDecl (NewTypeSig tc dc _ decl)
  = rnTyDecl    decl	`thenRn` \ rn_decl   ->
    lookupTyCon tc	`thenRn` \ rn_tc     ->
    lookupValue dc	`thenRn` \ rn_dc     ->
    getImplicitUpRn	`thenRn` \ mentioned ->
    let
	defds = ([(dc, rn_dc)], [(tc, rn_tc)])
	implicits = mentioned `sub` defds
    in
    returnRn (AddedTy rn_decl, defds, implicits)

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rnIfaceDecl (DataSig tc dcs fcs _ decl)
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  = rnTyDecl    decl		`thenRn` \ rn_decl   ->
    lookupTyCon tc		`thenRn` \ rn_tc     ->
    mapRn lookupValue dcs	`thenRn` \ rn_dcs    ->
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    mapRn lookupValue fcs	`thenRn` \ rn_fcs    ->
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    getImplicitUpRn		`thenRn` \ mentioned ->
    let
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	defds = (zip dcs rn_dcs ++ zip fcs rn_fcs , [(tc, rn_tc)])
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	implicits = mentioned `sub` defds
    in
    returnRn (AddedTy rn_decl, defds, implicits)

rnIfaceDecl (ClassSig clas ops _ decl)
  = rnClassDecl decl			`thenRn` \ rn_decl   ->
    lookupClass clas			`thenRn` \ rn_clas   ->
    mapRn (lookupClassOp rn_clas) ops	`thenRn` \ rn_ops    ->
    getImplicitUpRn			`thenRn` \ mentioned ->
    let
	defds = (ops `zip` rn_ops, [(clas, rn_clas)])
	implicits = mentioned `sub` defds
    in
    returnRn (AddedClass rn_decl, defds, implicits)

rnIfaceDecl (ValSig f src_loc ty)
    -- should rename_sig in RnBinds be used here? ToDo
  = lookupValue f			`thenRn` \ rn_f  ->
    -- pprTrace "rnIfaceDecl:ValSig:" (ppr PprDebug ty) $
    rnPolyType nullTyVarNamesEnv ty	`thenRn` \ rn_ty ->
    getImplicitUpRn			`thenRn` \ mentioned ->
    let
	defds = ([(f, rn_f)], [])
	implicits = mentioned `sub` defds
    in
    returnRn (AddedSig (Sig rn_f rn_ty noGenPragmas src_loc), defds, implicits)

----
sub :: ImplicitEnv -> ([(RdrName,RnName)], [(RdrName,RnName)]) -> ImplicitEnv

sub (val_ment, tc_ment) (val_defds, tc_defds)
  = (delListFromFM val_ment (map fst val_defds),
     delListFromFM tc_ment  (map fst tc_defds))
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\end{code}

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% ------------------------------

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@cacheInstModules@: cache instance modules specified in imports

\begin{code}
cacheInstModules :: IfaceCache -> [Module] -> IO (Bag Error)
cacheInstModules iface_cache imp_mods
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  = readVar iface_cache		`thenPrimIO` \ (iface_fm, _, _) ->
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    let
	imp_ifaces      = [ iface | Just iface <- map (lookupFM iface_fm) imp_mods ]
	(imp_imods, _)  = removeDups cmpPString (bagToList (unionManyBags (map get_ims imp_ifaces)))
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        get_ims (ParsedIface _ _ _ _ _ _ _ ims _ _ _ _ _) = ims
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    in
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    accumulate (map (cachedIface False iface_cache) imp_imods) >>= \ err_or_ifaces ->
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    -- Sanity Check:
    -- Assert that instance modules given by direct imports contains
    -- instance modules extracted from all visited modules

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    readVar iface_cache		`thenPrimIO` \ (all_iface_fm, _, _) ->
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    let
	all_ifaces     = eltsFM all_iface_fm
	(all_imods, _) = removeDups cmpPString (bagToList (unionManyBags (map get_ims (all_ifaces))))
    in
    ASSERT(sortLt (<) imp_imods == sortLt (<) all_imods)

    return (bag_errs err_or_ifaces)
  where
    bag_errs [] = emptyBag
    bag_errs (Failed err :rest) = err `consBag` bag_errs rest
    bag_errs (Succeeded _:rest) = bag_errs rest
\end{code}


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@rnIfaceInstStuff@: Deal with instance declarations from interface files.

\begin{code}
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type InstanceEnv = FiniteMap (RdrName, RdrName) Int

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rnIfaceInstStuff
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	:: IfaceCache		-- all about ifaces we've read
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	-> Module
	-> UniqSupply
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	-> RnEnv		-- current occ env
	-> InstanceEnv  	-- instances for these tycon/class pairs done
	-> To_Return
	-> IO (To_Return,
	       InstanceEnv,	-- extended instance env
	       RnEnv,		-- final occ env
	       [RnName])	-- new unknown names

rnIfaceInstStuff iface_cache modname us occ_env done_inst_env to_return
  = -- all the instance decls we might even want to consider
    -- are in the ParsedIfaces that are in our cache
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    readVar iface_cache	`thenPrimIO` \ (_, orig_iface_fm, _) ->
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    let
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	all_ifaces	  = eltsFM orig_iface_fm
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	all_insts	  = unionManyBags (map get_insts all_ifaces)
	interesting_insts = filter want_inst (bagToList all_insts)
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	-- Sanity Check:
	-- Assert that there are no more instances for the done instances
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	claim_done       = filter is_done_inst (bagToList all_insts)
	claim_done_env   = foldr add_done_inst emptyFM claim_done
	has_val fm (k,i) = case lookupFM fm k of { Nothing -> False; Just v -> i == v }
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    in
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    {-
      pprTrace "all_insts:\n"         (ppr_insts (bagToList all_insts)) $
      pprTrace "interesting_insts:\n" (ppr_insts interesting_insts) $
    -}
    ASSERT(sizeFM done_inst_env == sizeFM claim_done_env)
    ASSERT(all (has_val claim_done_env) (fmToList done_inst_env))
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    case (initRn False{-iface-} modname occ_env us (
	    setExtraRn emptyUFM{-no fixities-}	$
	    mapRn rnIfaceInst interesting_insts `thenRn` \ insts ->
	    getImplicitUpRn 			`thenRn` \ implicits ->
	    returnRn (insts, implicits))) of {
      ((if_insts, if_implicits), if_errs, if_warns) ->

	return (add_insts      if_insts		$
		 add_implicits if_implicits	$
		  add_errs     if_errs		$
		   add_warns   if_warns to_return,
		foldr add_done_inst done_inst_env interesting_insts,
		add_imp_occs if_implicits occ_env,
		eltsFM (fst if_implicits) ++ eltsFM (snd if_implicits))
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    }
  where
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    get_insts (ParsedIface _ _ _ _ _ _ _ _ _ _ _ insts _) = insts
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    add_done_inst (InstSig clas tycon _ _) inst_env
      = addToFM_C (+) inst_env (tycon,clas) 1

    is_done_inst (InstSig clas tycon _ _)
      = maybeToBool (lookupFM done_inst_env (tycon,clas))

    add_imp_occs (val_imps, tc_imps) occ_env
      = case extendGlobalRnEnv occ_env (fmToList val_imps) (fmToList tc_imps) of
     	  (ext_occ_env, occ_dups) -> ASSERT(isEmptyBag occ_dups)
				     ext_occ_env

    want_inst i@(InstSig clas tycon _ _)
      = -- it's a "good instance" (one to hang onto) if we have a
	-- chance of referring to *both* the class and tycon later on ...

	mentionable tycon && mentionable clas && not (is_done_inst i)
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      where
	mentionable nm
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	  = case lookupTcRnEnv occ_env nm of
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	      Just  _ -> True
	      Nothing -> -- maybe it's builtin
		case nm of
		  Qual _ _ -> False
		  Unqual n ->
		    case (lookupFM b_tc_names n) of
		      Just  _ -> True
		      Nothing -> maybeToBool (lookupFM b_keys n)

    (b_tc_names, b_keys) -- pretty UGLY ...
      = case builtinNameInfo of ((_,builtin_tcs),b_keys,_) -> (builtin_tcs,b_keys)

    ppr_insts insts
      = ppAboves (map ppr_inst insts)
      where
	ppr_inst (InstSig c t _ inst_decl)
	  = ppCat [ppr PprDebug c, ppr PprDebug t, ppr PprDebug inst_decl]
\end{code}

\begin{code}
rnIfaceInst :: RdrIfaceInst -> RnM_Fixes _RealWorld RenamedInstDecl

rnIfaceInst (InstSig _ _ _ inst_decl) = rnInstDecl inst_decl
\end{code}
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\begin{code}
finalIfaceInfo ::
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	   IfaceCache			-- iface cache
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	-> Module			-- this module's name
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	-> RnEnv
	-> [RenamedInstDecl]
--	-> [RnName]			-- all imported names required
--	-> [Module]			-- directly imported modules
	-> IO (UsagesMap,
	       VersionsMap,		-- info about version numbers
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	       [Module])		-- special instance modules
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finalIfaceInfo iface_cache modname if_final_env@((qual, unqual, tc_qual, tc_unqual), stack) if_instdecls
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  =
    pprTrace "usageIf:qual:"      (ppCat [ppBesides[ppPStr m,ppChar '.',ppPStr n] | (n,m) <- keysFM qual]) $
--  pprTrace "usageIf:unqual:"    (ppCat (map ppPStr (keysFM unqual))) $
    pprTrace "usageIf:tc_qual:"   (ppCat [ppBesides[ppPStr m,ppChar '.',ppPStr n] | (n,m) <- keysFM tc_qual]) $
--  pprTrace "usageIf:tc_unqual:" (ppCat (map ppPStr (keysFM tc_unqual))) $
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    let
	val_stuff@(val_usages, val_versions)
	  = foldFM process_item (emptyFM, emptyFM){-init-} qual
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	(all_usages, all_versions)
	  = foldFM process_item val_stuff{-keep going-} tc_qual
    in
    return (all_usages, all_versions, [])
  where
    process_item :: (FAST_STRING,Module) -> RnName -- RnEnv (QualNames) components
		 -> (UsagesMap, VersionsMap)	   -- input
		 -> (UsagesMap, VersionsMap)	   -- output

    process_item (n,m) rn as_before@(usages, versions)
      | irrelevant rn
      = as_before
      | m == modname -- this module => add to "versions"
      =	(usages, addToFM versions n 1{-stub-})
      | otherwise  -- from another module => add to "usages"
      = (add_to_usages usages m n 1{-stub-}, versions)

    irrelevant (RnConstr  _ _) = True	-- We don't report these in their
    irrelevant (RnField   _ _) = True	-- own right in usages/etc.
    irrelevant (RnClassOp _ _) = True
    irrelevant _	       = False

    add_to_usages usages m n version
      = addToFM usages m (
	    case (lookupFM usages m) of
	      Nothing -> -- nothing for this module yet...
		(1{-stub-}, unitFM n version)

	      Just (mversion, mstuff) -> -- the "new" stuff will shadow the old
		(mversion, addToFM mstuff n version)
	)
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\end{code}


\begin{code}
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thisModImplicitErr mod n sty
  = ppCat [ppPStr SLIT("Implicit import of"), ppr sty n, ppPStr SLIT("when compiling"), ppPStr mod]

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noIfaceErr mod sty
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  = ppCat [ppPStr SLIT("Could not find interface for:"), ppPStr mod]

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noOrigIfaceErr mod sty
  = ppCat [ppPStr SLIT("Could not find original interface for:"), ppPStr mod]

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noDeclInIfaceErr mod str sty
  = ppBesides [ppPStr SLIT("Could not find interface declaration of: "),
	       ppPStr mod, ppStr ".", ppPStr str]

cannaeReadErr file err sty
  = ppBesides [ppPStr SLIT("Failed in reading file: "), ppStr file, ppStr "; error=", ppStr (show err)]

ifaceLookupWiredErr msg n sty
  = ppBesides [ppPStr SLIT("Why am I looking up a wired-in "), ppStr msg, ppChar ':', ppr sty n]

badIfaceLookupErr msg name decl sty
  = ppBesides [ppPStr SLIT("Expected a "), ppStr msg, ppPStr SLIT(" declaration, but got this: ???")]
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\end{code}