RnSource.lhs 31.7 KB
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%
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% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
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%
\section[RnSource]{Main pass of renamer}

\begin{code}
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module RnSource ( 
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	rnSrcDecls, addTcgDUs, 
	rnTyClDecls, checkModDeprec,
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	rnSplice, checkTH
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    ) where
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#include "HsVersions.h"
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import {-# SOURCE #-} RnExpr( rnLExpr )

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import HsSyn
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import RdrName		( RdrName, isRdrDataCon, isRdrTyVar, rdrNameOcc, 
			  elemLocalRdrEnv, globalRdrEnvElts, GlobalRdrElt(..),
			  isLocalGRE )
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import RdrHsSyn		( extractGenericPatTyVars, extractHsRhoRdrTyVars )
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import RnHsSyn
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import RnTypes		( rnLHsType, rnLHsTypes, rnHsSigType, rnHsTypeFVs, rnContext )
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import RnBinds		( rnTopBinds, rnMethodBinds, renameSigs, mkSigTvFn )
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import RnEnv		( lookupLocalDataTcNames,
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			  lookupLocatedTopBndrRn, lookupLocatedOccRn,
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			  lookupOccRn, newLocalsRn, 
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			  bindLocatedLocalsFV, bindPatSigTyVarsFV,
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			  bindTyVarsRn, extendTyVarEnvFVRn,
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			  bindLocalNames, checkDupNames, mapFvRn
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			)
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import TcRnMonad
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import HscTypes		( FixityEnv, FixItem(..),
			  Deprecations, Deprecs(..), DeprecTxt, plusDeprecs )
import Class		( FunDep )
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import Name		( Name, nameOccName )
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import NameSet
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import NameEnv
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import OccName		( occEnvElts )
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import Outputable
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import SrcLoc		( Located(..), unLoc, noLoc )
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import DynFlags	( DynFlag(..) )
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import Maybes		( seqMaybe )
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import Maybe            ( isNothing, catMaybes )
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import Monad		( liftM )
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import BasicTypes       ( Boxity(..) )
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\end{code}

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@rnSourceDecl@ `renames' declarations.
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It simultaneously performs dependency analysis and precedence parsing.
It also does the following error checks:
\begin{enumerate}
\item
Checks that tyvars are used properly. This includes checking
for undefined tyvars, and tyvars in contexts that are ambiguous.
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(Some of this checking has now been moved to module @TcMonoType@,
since we don't have functional dependency information at this point.)
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\item
Checks that all variable occurences are defined.
\item 
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Checks the @(..)@ etc constraints in the export list.
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\end{enumerate}


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\begin{code}
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rnSrcDecls :: HsGroup RdrName -> RnM (TcGblEnv, HsGroup Name)
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rnSrcDecls (HsGroup { hs_valds  = val_decls,
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		      hs_tyclds = tycl_decls,
		      hs_instds = inst_decls,
		      hs_fixds  = fix_decls,
		      hs_depds  = deprec_decls,
		      hs_fords  = foreign_decls,
		      hs_defds  = default_decls,
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		      hs_ruleds = rule_decls })
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 = do {		-- Deal with deprecations (returns only the extra deprecations)
	deprecs <- rnSrcDeprecDecls deprec_decls ;
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	updGblEnv (\gbl -> gbl { tcg_deprecs = tcg_deprecs gbl `plusDeprecs` deprecs })
		  $ do {

		-- Deal with top-level fixity decls 
		-- (returns the total new fixity env)
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        rn_fix_decls <- rnSrcFixityDecls fix_decls ;
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	fix_env <- rnSrcFixityDeclsEnv rn_fix_decls ;
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	updGblEnv (\gbl -> gbl { tcg_fix_env = fix_env })
		  $ do {

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		-- Rename other declarations
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	traceRn (text "Start rnmono") ;
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	(rn_val_decls, bind_dus) <- rnTopBinds val_decls ;
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	traceRn (text "finish rnmono" <+> ppr rn_val_decls) ;
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		-- You might think that we could build proper def/use information
		-- for type and class declarations, but they can be involved
		-- in mutual recursion across modules, and we only do the SCC
		-- analysis for them in the type checker.
		-- So we content ourselves with gathering uses only; that
		-- means we'll only report a declaration as unused if it isn't
		-- mentioned at all.  Ah well.
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	(rn_tycl_decls,    src_fvs1)
	   <- mapFvRn (wrapLocFstM rnTyClDecl) tycl_decls ;
	(rn_inst_decls,    src_fvs2)
	   <- mapFvRn (wrapLocFstM rnSrcInstDecl) inst_decls ;
	(rn_rule_decls,    src_fvs3)
	   <- mapFvRn (wrapLocFstM rnHsRuleDecl) rule_decls ;
	(rn_foreign_decls, src_fvs4)
	   <- mapFvRn (wrapLocFstM rnHsForeignDecl) foreign_decls ;
	(rn_default_decls, src_fvs5)
	   <- mapFvRn (wrapLocFstM rnDefaultDecl) default_decls ;
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	let {
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           rn_at_decls = concat 
			   [ats | L _ (InstDecl _ _ _ ats) <- rn_inst_decls] ;
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	   rn_group = HsGroup { hs_valds  = rn_val_decls,
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			    	hs_tyclds = rn_tycl_decls ++ rn_at_decls,
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			    	hs_instds = rn_inst_decls,
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			    	hs_fixds  = rn_fix_decls,
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			    	hs_depds  = [],
			    	hs_fords  = rn_foreign_decls,
			    	hs_defds  = rn_default_decls,
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			    	hs_ruleds = rn_rule_decls } ;
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	   other_fvs = plusFVs [src_fvs1, src_fvs2, src_fvs3, 
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				src_fvs4, src_fvs5] ;
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	   src_dus = bind_dus `plusDU` usesOnly other_fvs 
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		-- Note: src_dus will contain *uses* for locally-defined types
		-- and classes, but no *defs* for them.  (Because rnTyClDecl 
		-- returns only the uses.)  This is a little 
		-- surprising but it doesn't actually matter at all.
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	} ;

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	traceRn (text "finish rnSrc" <+> ppr rn_group) ;
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	traceRn (text "finish Dus" <+> ppr src_dus ) ;
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	tcg_env <- getGblEnv ;
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	return (tcg_env `addTcgDUs` src_dus, rn_group)
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    }}}
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rnTyClDecls :: [LTyClDecl RdrName] -> RnM [LTyClDecl Name]
rnTyClDecls tycl_decls = do 
  (decls', fvs) <- mapFvRn (wrapLocFstM rnTyClDecl) tycl_decls
  return decls'
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addTcgDUs :: TcGblEnv -> DefUses -> TcGblEnv 
addTcgDUs tcg_env dus = tcg_env { tcg_dus = tcg_dus tcg_env `plusDU` dus }
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\end{code}


%*********************************************************
%*						 	 *
	Source-code fixity declarations
%*							 *
%*********************************************************

\begin{code}
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rnSrcFixityDecls :: [LFixitySig RdrName] -> RnM [LFixitySig Name]
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rnSrcFixityDecls fix_decls
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    = do fix_decls <- mapM rnFixityDecl fix_decls
         return (concat fix_decls)

rnFixityDecl :: LFixitySig RdrName -> RnM [LFixitySig Name]
rnFixityDecl (L loc (FixitySig (L nameLoc rdr_name) fixity))
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    = setSrcSpan nameLoc $
        -- GHC extension: look up both the tycon and data con 
	-- for con-like things
	-- If neither are in scope, report an error; otherwise
	-- add both to the fixity env
      do names <- lookupLocalDataTcNames rdr_name
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         return [ L loc (FixitySig (L nameLoc name) fixity)
                      | name <- names ]

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rnSrcFixityDeclsEnv :: [LFixitySig Name] -> RnM FixityEnv
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rnSrcFixityDeclsEnv fix_decls
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  = getGblEnv					`thenM` \ gbl_env ->
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    foldlM rnFixityDeclEnv (tcg_fix_env gbl_env) 
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	    fix_decls				 	`thenM` \ fix_env ->
    traceRn (text "fixity env" <+> pprFixEnv fix_env)	`thenM_`
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    returnM fix_env

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rnFixityDeclEnv :: FixityEnv -> LFixitySig Name -> RnM FixityEnv
rnFixityDeclEnv fix_env (L loc (FixitySig (L nameLoc name) fixity))
  = case lookupNameEnv fix_env name of
      Just (FixItem _ _ loc') 
	  -> do addLocErr (L nameLoc name) (dupFixityDecl loc')
    	        return fix_env
      Nothing
          -> return (extendNameEnv fix_env name fix_item)
    where fix_item = FixItem (nameOccName name) fixity nameLoc
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pprFixEnv :: FixityEnv -> SDoc
pprFixEnv env 
  = pprWithCommas (\ (FixItem n f _) -> ppr f <+> ppr n)
		  (nameEnvElts env)
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dupFixityDecl loc rdr_name
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  = vcat [ptext SLIT("Multiple fixity declarations for") <+> quotes (ppr rdr_name),
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	  ptext SLIT("also at ") <+> ppr loc
	]
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\end{code}


%*********************************************************
%*						 	 *
	Source-code deprecations declarations
%*							 *
%*********************************************************

For deprecations, all we do is check that the names are in scope.
It's only imported deprecations, dealt with in RnIfaces, that we
gather them together.

\begin{code}
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rnSrcDeprecDecls :: [LDeprecDecl RdrName] -> RnM Deprecations
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rnSrcDeprecDecls [] 
  = returnM NoDeprecs

rnSrcDeprecDecls decls
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  = mappM (addLocM rn_deprec) decls	`thenM` \ pairs_s ->
    returnM (DeprecSome (mkNameEnv (concat pairs_s)))
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 where
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   rn_deprec (Deprecation rdr_name txt)
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     = lookupLocalDataTcNames rdr_name	`thenM` \ names ->
       returnM [(name, (nameOccName name, txt)) | name <- names]
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checkModDeprec :: Maybe DeprecTxt -> Deprecations
-- Check for a module deprecation; done once at top level
checkModDeprec Nothing    = NoDeprecs
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checkModDeprec (Just txt) = DeprecAll txt
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\end{code}
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%*********************************************************
%*							*
\subsection{Source code declarations}
%*							*
%*********************************************************
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\begin{code}
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rnDefaultDecl (DefaultDecl tys)
  = mapFvRn (rnHsTypeFVs doc_str) tys	`thenM` \ (tys', fvs) ->
    returnM (DefaultDecl tys', fvs)
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  where
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    doc_str = text "In a `default' declaration"
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\end{code}

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%*********************************************************
%*							*
\subsection{Foreign declarations}
%*							*
%*********************************************************

\begin{code}
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rnHsForeignDecl (ForeignImport name ty spec)
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  = lookupLocatedTopBndrRn name	        `thenM` \ name' ->
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    rnHsTypeFVs (fo_decl_msg name) ty	`thenM` \ (ty', fvs) ->
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    returnM (ForeignImport name' ty' spec, fvs)
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rnHsForeignDecl (ForeignExport name ty spec)
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  = lookupLocatedOccRn name	        `thenM` \ name' ->
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    rnHsTypeFVs (fo_decl_msg name) ty  	`thenM` \ (ty', fvs) ->
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    returnM (ForeignExport name' ty' spec, fvs )
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	-- NB: a foreign export is an *occurrence site* for name, so 
	--     we add it to the free-variable list.  It might, for example,
	--     be imported from another module
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fo_decl_msg name = ptext SLIT("In the foreign declaration for") <+> ppr name
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\end{code}


%*********************************************************
%*							*
\subsection{Instance declarations}
%*							*
%*********************************************************

\begin{code}
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rnSrcInstDecl (InstDecl inst_ty mbinds uprags ats)
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	-- Used for both source and interface file decls
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  = rnHsSigType (text "an instance decl") inst_ty	`thenM` \ inst_ty' ->
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	-- Rename the associated types
	-- The typechecker (not the renamer) checks that all 
	-- the declarations are for the right class
    let
	at_doc   = text "In the associated types in an instance declaration"
	at_names = map (head . tyClDeclNames . unLoc) ats
	(_, rdrCtxt, _, _) = splitHsInstDeclTy (unLoc inst_ty)
    in
    checkDupNames at_doc at_names		`thenM_`
    rnATDefs rdrCtxt ats			`thenM` \ (ats', at_fvs) ->

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	-- Rename the bindings
	-- The typechecker (not the renamer) checks that all 
	-- the bindings are for the right class
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    let
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	meth_doc    = text "In the bindings in an instance declaration"
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	meth_names  = collectHsBindLocatedBinders mbinds
	(inst_tyvars, _, cls,_) = splitHsInstDeclTy (unLoc inst_ty')
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    in
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    checkDupNames meth_doc meth_names 	`thenM_`
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    extendTyVarEnvForMethodBinds inst_tyvars (		
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	-- (Slightly strangely) the forall-d tyvars scope over
	-- the method bindings too
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	rnMethodBinds cls (\n->[]) 	-- No scoped tyvars
		      [] mbinds
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    )						`thenM` \ (mbinds', meth_fvs) ->
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	-- Rename the prags and signatures.
	-- Note that the type variables are not in scope here,
	-- so that	instance Eq a => Eq (T a) where
	--			{-# SPECIALISE instance Eq a => Eq (T [a]) #-}
	-- works OK. 
	--
	-- But the (unqualified) method names are in scope
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    let 
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	binders = collectHsBindBinders mbinds'
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	ok_sig  = okInstDclSig (mkNameSet binders)
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    in
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    bindLocalNames binders (renameSigs ok_sig uprags)	`thenM` \ uprags' ->
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    returnM (InstDecl inst_ty' mbinds' uprags' ats',
	     meth_fvs `plusFV` at_fvs
		      `plusFV` hsSigsFVs uprags'
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		      `plusFV` extractHsTyNames inst_ty')
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             -- We return the renamed associated data type declarations so
             -- that they can be entered into the list of type declarations
             -- for the binding group, but we also keep a copy in the instance.
             -- The latter is needed for well-formedness checks in the type
             -- checker (eg, to ensure that all ATs of the instance actually
             -- receive a declaration). 
	     -- NB: Even the copies in the instance declaration carry copies of
	     --     the instance context after renaming.  This is a bit
	     --     strange, but should not matter (and it would be more work
	     --     to remove the context).
\end{code}

Renaming of the associated data definitions requires adding the instance
context, as the rhs of an AT declaration may use ATs from classes in the
context.

\begin{code}
rnATDefs :: HsContext RdrName -> [LTyClDecl RdrName] 
	  -> RnM ([LTyClDecl Name], FreeVars)
rnATDefs ctxt atDecls = 
  mapFvRn (wrapLocFstM addCtxtAndRename) atDecls
  where
    -- The parser won't accept anything, but a data declaration
    addCtxtAndRename ty@TyData {tcdCtxt = L l tyCtxt} = 
      rnTyClDecl (ty {tcdCtxt = L l (ctxt ++ tyCtxt)})
      -- The source loc is somewhat half hearted... -=chak
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\end{code}

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For the method bindings in class and instance decls, we extend the 
type variable environment iff -fglasgow-exts

\begin{code}
extendTyVarEnvForMethodBinds tyvars thing_inside
  = doptM Opt_GlasgowExts			`thenM` \ opt_GlasgowExts ->
    if opt_GlasgowExts then
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	extendTyVarEnvFVRn (map hsLTyVarName tyvars) thing_inside
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    else
	thing_inside
\end{code}


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%*********************************************************
%*							*
\subsection{Rules}
%*							*
%*********************************************************

\begin{code}
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rnHsRuleDecl (HsRule rule_name act vars lhs fv_lhs rhs fv_rhs)
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  = bindPatSigTyVarsFV (collectRuleBndrSigTys vars)	$
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    bindLocatedLocalsFV doc (map get_var vars)		$ \ ids ->
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    mapFvRn rn_var (vars `zip` ids)		`thenM` \ (vars', fv_vars) ->
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    rnLExpr lhs					`thenM` \ (lhs', fv_lhs') ->
    rnLExpr rhs					`thenM` \ (rhs', fv_rhs') ->
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    checkValidRule rule_name ids lhs' fv_lhs'	`thenM_`

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    returnM (HsRule rule_name act vars' lhs' fv_lhs' rhs' fv_rhs',
	     fv_vars `plusFV` fv_lhs' `plusFV` fv_rhs')
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  where
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    doc = text "In the transformation rule" <+> ftext rule_name
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    get_var (RuleBndr v)      = v
    get_var (RuleBndrSig v _) = v

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    rn_var (RuleBndr (L loc v), id)
	= returnM (RuleBndr (L loc id), emptyFVs)
    rn_var (RuleBndrSig (L loc v) t, id)
	= rnHsTypeFVs doc t	`thenM` \ (t', fvs) ->
	  returnM (RuleBndrSig (L loc id) t', fvs)
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badRuleVar name var
  = sep [ptext SLIT("Rule") <+> doubleQuotes (ftext name) <> colon,
	 ptext SLIT("Forall'd variable") <+> quotes (ppr var) <+> 
		ptext SLIT("does not appear on left hand side")]
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\end{code}

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Note [Rule LHS validity checking]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Check the shape of a transformation rule LHS.  Currently we only allow
LHSs of the form @(f e1 .. en)@, where @f@ is not one of the
@forall@'d variables.  
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We used restrict the form of the 'ei' to prevent you writing rules
with LHSs with a complicated desugaring (and hence unlikely to match);
(e.g. a case expression is not allowed: too elaborate.)
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But there are legitimate non-trivial args ei, like sections and
lambdas.  So it seems simmpler not to check at all, and that is why
check_e is commented out.
	
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\begin{code}
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checkValidRule rule_name ids lhs' fv_lhs'
  = do 	{ 	-- Check for the form of the LHS
	  case (validRuleLhs ids lhs') of
		Nothing  -> return ()
		Just bad -> failWithTc (badRuleLhsErr rule_name lhs' bad)

		-- Check that LHS vars are all bound
	; let bad_vars = [var | var <- ids, not (var `elemNameSet` fv_lhs')]
	; mappM (addErr . badRuleVar rule_name) bad_vars }

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validRuleLhs :: [Name] -> LHsExpr Name -> Maybe (HsExpr Name)
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-- Nothing => OK
-- Just e  => Not ok, and e is the offending expression
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validRuleLhs foralls lhs
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  = checkl lhs
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  where
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    checkl (L loc e) = check e

    check (OpApp e1 op _ e2)		  = checkl op `seqMaybe` checkl_e e1 `seqMaybe` checkl_e e2
    check (HsApp e1 e2) 		  = checkl e1 `seqMaybe` checkl_e e2
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    check (HsVar v) | v `notElem` foralls = Nothing
    check other				  = Just other 	-- Failure

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	-- Check an argument
    checkl_e (L loc e) = Nothing 	-- Was (check_e e); see Note [Rule LHS validity checking]
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{-	Commented out; see Note [Rule LHS validity checking] above 
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    check_e (HsVar v)     = Nothing
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    check_e (HsPar e) 	  = checkl_e e
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    check_e (HsLit e) 	  = Nothing
    check_e (HsOverLit e) = Nothing

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    check_e (OpApp e1 op _ e2) 	 = checkl_e e1 `seqMaybe` checkl_e op `seqMaybe` checkl_e e2
    check_e (HsApp e1 e2)      	 = checkl_e e1 `seqMaybe` checkl_e e2
    check_e (NegApp e _)       	 = checkl_e e
    check_e (ExplicitList _ es)	 = checkl_es es
    check_e (ExplicitTuple es _) = checkl_es es
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    check_e other		 = Just other	-- Fails

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    checkl_es es = foldr (seqMaybe . checkl_e) Nothing es
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-}
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badRuleLhsErr name lhs bad_e
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  = sep [ptext SLIT("Rule") <+> ftext name <> colon,
	 nest 4 (vcat [ptext SLIT("Illegal expression:") <+> ppr bad_e, 
		       ptext SLIT("in left-hand side:") <+> ppr lhs])]
    $$
    ptext SLIT("LHS must be of form (f e1 .. en) where f is not forall'd")
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\end{code}

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%*********************************************************
%*							*
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\subsection{Type, class and iface sig declarations}
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%*							*
%*********************************************************

@rnTyDecl@ uses the `global name function' to create a new type
declaration in which local names have been replaced by their original
names, reporting any unknown names.

Renaming type variables is a pain. Because they now contain uniques,
it is necessary to pass in an association list which maps a parsed
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tyvar to its @Name@ representation.
In some cases (type signatures of values),
it is even necessary to go over the type first
in order to get the set of tyvars used by it, make an assoc list,
and then go over it again to rename the tyvars!
However, we can also do some scoping checks at the same time.
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\begin{code}
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rnTyClDecl (ForeignType {tcdLName = name, tcdFoType = fo_type, tcdExtName = ext_name})
  = lookupLocatedTopBndrRn name		`thenM` \ name' ->
    returnM (ForeignType {tcdLName = name', tcdFoType = fo_type, tcdExtName = ext_name},
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	     emptyFVs)
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rnTyClDecl (TyData {tcdND = new_or_data, tcdCtxt = context, tcdLName = tycon,
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		    tcdTyVars = tyvars, tcdTyPats = typatsMaybe, 
		    tcdCons = condecls, tcdKindSig = sig, tcdDerivs = derivs})
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  | is_vanilla	-- Normal Haskell data type decl
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  = ASSERT( isNothing sig )	-- In normal H98 form, kind signature on the 
				-- data type is syntactically illegal
    bindTyVarsRn data_doc tyvars		$ \ tyvars' ->
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    do	{ tycon' <- lookupLocatedTopBndrRn tycon
	; context' <- rnContext data_doc context
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	; typats' <- rnTyPats data_doc typatsMaybe
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	; (derivs', deriv_fvs) <- rn_derivs derivs
	; checkDupNames data_doc con_names
	; condecls' <- rnConDecls (unLoc tycon') condecls
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	; returnM (TyData {tcdND = new_or_data, tcdCtxt = context', 
			   tcdLName = tycon', tcdTyVars = tyvars', 
			   tcdTyPats = typats', tcdKindSig = Nothing, 
			   tcdCons = condecls', tcdDerivs = derivs'}, 
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		   delFVs (map hsLTyVarName tyvars')	$
	     	   extractHsCtxtTyNames context'	`plusFV`
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	     	   plusFVs (map conDeclFVs condecls')   `plusFV`
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	     	   deriv_fvs) }

  | otherwise	-- GADT
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  = ASSERT( none typatsMaybe )    -- GADTs cannot have type patterns for now
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    do	{ tycon' <- lookupLocatedTopBndrRn tycon
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	; checkTc (null (unLoc context)) (badGadtStupidTheta tycon)
    	; tyvars' <- bindTyVarsRn data_doc tyvars 
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				  (\ tyvars' -> return tyvars')
		-- For GADTs, the type variables in the declaration 
		-- do not scope over the constructor signatures
		-- 	data T a where { T1 :: forall b. b-> b }
	; (derivs', deriv_fvs) <- rn_derivs derivs
	; checkDupNames data_doc con_names
	; condecls' <- rnConDecls (unLoc tycon') condecls
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	; returnM (TyData {tcdND = new_or_data, tcdCtxt = noLoc [], 
			   tcdLName = tycon', tcdTyVars = tyvars', 
			   tcdTyPats = Nothing, tcdKindSig = sig,
			   tcdCons = condecls', tcdDerivs = derivs'}, 
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	     	   plusFVs (map conDeclFVs condecls') `plusFV` deriv_fvs) }

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  where
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    is_vanilla = case condecls of	-- Yuk
		     [] 		   -> True
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		     L _ (ConDecl { con_res = ResTyH98 }) : _  -> True
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		     other		   -> False

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    none Nothing   = True
    none (Just []) = True
    none _         = False

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    data_doc = text "In the data type declaration for" <+> quotes (ppr tycon)
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    con_names = map con_names_helper condecls

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    con_names_helper (L _ c) = con_name c
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    rn_derivs Nothing   = returnM (Nothing, emptyFVs)
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    rn_derivs (Just ds) = rnLHsTypes data_doc ds	`thenM` \ ds' -> 
			  returnM (Just ds', extractHsTyNames_s ds')
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rnTyClDecl (TySynonym {tcdLName = name, tcdTyVars = tyvars, tcdSynRhs = ty})
  = lookupLocatedTopBndrRn name			`thenM` \ name' ->
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    bindTyVarsRn syn_doc tyvars 		$ \ tyvars' ->
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    rnHsTypeFVs syn_doc ty			`thenM` \ (ty', fvs) ->
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    returnM (TySynonym {tcdLName = name', tcdTyVars = tyvars', 
			tcdSynRhs = ty'},
	     delFVs (map hsLTyVarName tyvars') fvs)
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  where
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    syn_doc = text "In the declaration for type synonym" <+> quotes (ppr name)
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rnTyClDecl (ClassDecl {tcdCtxt = context, tcdLName = cname, 
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		       tcdTyVars = tyvars, tcdFDs = fds, tcdSigs = sigs, 
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		       tcdMeths = mbinds, tcdATs = ats})
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  = lookupLocatedTopBndrRn cname		`thenM` \ cname' ->
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	-- Tyvars scope over superclass context and method signatures
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    bindTyVarsRn cls_doc tyvars			( \ tyvars' ->
	rnContext cls_doc context	`thenM` \ context' ->
	rnFds cls_doc fds		`thenM` \ fds' ->
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	rnATs tyvars' ats		`thenM` \ (ats', ats_fvs) ->
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	renameSigs okClsDclSig sigs	`thenM` \ sigs' ->
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	returnM   (tyvars', context', fds', (ats', ats_fvs), sigs')
    )	`thenM` \ (tyvars', context', fds', (ats', ats_fvs), sigs') ->

	-- Check for duplicates among the associated types
    let
      at_rdr_names_w_locs      = [tcdLName ty | L _ ty <- ats]
    in
    checkDupNames at_doc at_rdr_names_w_locs   `thenM_`
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	-- Check the signatures
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	-- First process the class op sigs (op_sigs), then the fixity sigs (non_op_sigs).
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    let
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	sig_rdr_names_w_locs   = [op | L _ (TypeSig op _) <- sigs]
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    in
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    checkDupNames sig_doc sig_rdr_names_w_locs	`thenM_` 
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	-- Typechecker is responsible for checking that we only
	-- give default-method bindings for things in this class.
	-- The renamer *could* check this for class decls, but can't
	-- for instance decls.

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   	-- The newLocals call is tiresome: given a generic class decl
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	--	class C a where
	--	  op :: a -> a
	--	  op {| x+y |} (Inl a) = ...
	--	  op {| x+y |} (Inr b) = ...
	--	  op {| a*b |} (a*b)   = ...
	-- we want to name both "x" tyvars with the same unique, so that they are
	-- easy to group together in the typechecker.  
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    extendTyVarEnvForMethodBinds tyvars' (
   	 getLocalRdrEnv					`thenM` \ name_env ->
   	 let
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 	     meth_rdr_names_w_locs = collectHsBindLocatedBinders mbinds
 	     gen_rdr_tyvars_w_locs = 
		[ tv | tv <- extractGenericPatTyVars mbinds,
 		      not (unLoc tv `elemLocalRdrEnv` name_env) ]
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   	 in
   	 checkDupNames meth_doc meth_rdr_names_w_locs	`thenM_`
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   	 newLocalsRn gen_rdr_tyvars_w_locs	`thenM` \ gen_tyvars ->
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   	 rnMethodBinds (unLoc cname') (mkSigTvFn sigs') gen_tyvars mbinds
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    ) `thenM` \ (mbinds', meth_fvs) ->

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    returnM (ClassDecl { tcdCtxt = context', tcdLName = cname', 
			 tcdTyVars = tyvars', tcdFDs = fds', tcdSigs = sigs',
			 tcdMeths = mbinds', tcdATs = ats'},
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	     delFVs (map hsLTyVarName tyvars')	$
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	     extractHsCtxtTyNames context'	    `plusFV`
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	     plusFVs (map extractFunDepNames (map unLoc fds'))  `plusFV`
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	     hsSigsFVs sigs'		  	    `plusFV`
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	     meth_fvs				    `plusFV`
	     ats_fvs)
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  where
    meth_doc = text "In the default-methods for class"	<+> ppr cname
    cls_doc  = text "In the declaration for class" 	<+> ppr cname
    sig_doc  = text "In the signatures for class"  	<+> ppr cname
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    at_doc   = text "In the associated types for class"	<+> ppr cname
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badGadtStupidTheta tycon
  = vcat [ptext SLIT("No context is allowed on a GADT-style data declaration"),
	  ptext SLIT("(You can put a context on each contructor, though.)")]
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\end{code}

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%*********************************************************
%*							*
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\subsection{Support code for type/data declarations}
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%*							*
%*********************************************************

\begin{code}
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-- Although, we are processing type patterns here, all type variables should
-- already be in scope (they are the same as in the 'tcdTyVars' field of the
-- type declaration to which these patterns belong)
--
rnTyPats :: SDoc -> Maybe [LHsType RdrName] -> RnM (Maybe [LHsType Name])
rnTyPats _   Nothing       = return Nothing
rnTyPats doc (Just typats) = liftM Just $ rnLHsTypes doc typats

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rnConDecls :: Name -> [LConDecl RdrName] -> RnM [LConDecl Name]
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rnConDecls tycon condecls
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  = mappM (wrapLocM rnConDecl) condecls
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rnConDecl :: ConDecl RdrName -> RnM (ConDecl Name)
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rnConDecl (ConDecl name expl tvs cxt details res_ty)
  = do	{ addLocM checkConName name
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	; new_name <- lookupLocatedTopBndrRn name
	; name_env <- getLocalRdrEnv
	
	-- For H98 syntax, the tvs are the existential ones
	-- For GADT syntax, the tvs are all the quantified tyvars
	-- Hence the 'filter' in the ResTyH98 case only
	; let not_in_scope  = not . (`elemLocalRdrEnv` name_env) . unLoc
	      arg_tys       = hsConArgs details
	      implicit_tvs  = case res_ty of
	      	    		ResTyH98 -> filter not_in_scope $
						get_rdr_tvs arg_tys
	      	    		ResTyGADT ty -> get_rdr_tvs (ty : arg_tys)
	      tvs' = case expl of
	        	Explicit -> tvs
		    	Implicit -> userHsTyVarBndrs implicit_tvs

	; bindTyVarsRn doc tvs' $ \new_tyvars -> do
	{ new_context <- rnContext doc cxt
        ; new_details <- rnConDetails doc details
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        ; (new_details', new_res_ty)  <- rnConResult doc new_details res_ty
        ; return (ConDecl new_name expl new_tyvars new_context new_details' new_res_ty) }}
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  where
    doc = text "In the definition of data constructor" <+> quotes (ppr name)
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    get_rdr_tvs tys  = extractHsRhoRdrTyVars cxt (noLoc (HsTupleTy Boxed tys))

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rnConResult _ details ResTyH98 = return (details, ResTyH98)

rnConResult doc details (ResTyGADT ty) = do
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    ty' <- rnHsSigType doc ty
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    let (arg_tys, res_ty) = splitHsFunType ty'
	-- We can split it up, now the renamer has dealt with fixities
    case details of
	PrefixCon _xs -> ASSERT( null _xs ) return (PrefixCon arg_tys, ResTyGADT res_ty)
	RecCon fields -> return (details, ResTyGADT ty')
	InfixCon {}   -> panic "rnConResult"
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rnConDetails doc (PrefixCon tys)
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  = mappM (rnLHsType doc) tys	`thenM` \ new_tys  ->
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    returnM (PrefixCon new_tys)
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rnConDetails doc (InfixCon ty1 ty2)
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  = rnLHsType doc ty1  		`thenM` \ new_ty1 ->
    rnLHsType doc ty2  		`thenM` \ new_ty2 ->
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    returnM (InfixCon new_ty1 new_ty2)
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rnConDetails doc (RecCon fields)
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  = checkDupNames doc field_names	`thenM_`
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    mappM (rnField doc) fields		`thenM` \ new_fields ->
    returnM (RecCon new_fields)
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  where
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    field_names = [fld | (fld, _) <- fields]
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rnField doc (name, ty)
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  = lookupLocatedTopBndrRn name	`thenM` \ new_name ->
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    rnLHsType doc ty		`thenM` \ new_ty ->
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    returnM (new_name, new_ty) 
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-- This data decl will parse OK
--	data T = a Int
-- treating "a" as the constructor.
-- It is really hard to make the parser spot this malformation.
-- So the renamer has to check that the constructor is legal
--
-- We can get an operator as the constructor, even in the prefix form:
--	data T = :% Int Int
-- from interface files, which always print in prefix form

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checkConName name = checkErr (isRdrDataCon name) (badDataCon name)

badDataCon name
   = hsep [ptext SLIT("Illegal data constructor name"), quotes (ppr name)]
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\end{code}

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%*********************************************************
%*							*
\subsection{Support code to rename types}
%*							*
%*********************************************************
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\begin{code}
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rnFds :: SDoc -> [Located (FunDep RdrName)] -> RnM [Located (FunDep Name)]
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rnFds doc fds
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  = mappM (wrapLocM rn_fds) fds
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  where
    rn_fds (tys1, tys2)
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      =	rnHsTyVars doc tys1		`thenM` \ tys1' ->
	rnHsTyVars doc tys2		`thenM` \ tys2' ->
	returnM (tys1', tys2')
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rnHsTyVars doc tvs  = mappM (rnHsTyvar doc) tvs
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rnHsTyvar doc tyvar = lookupOccRn tyvar
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-- Rename associated data type declarations
--
rnATs :: [LHsTyVarBndr Name] -> [LTyClDecl RdrName] 
      -> RnM ([LTyClDecl Name], FreeVars)
rnATs classLTyVars ats
  = mapFvRn (wrapLocFstM rn_at) ats
  where
    -- The parser won't accept anything, but a data declarations
    rn_at (tydecl@TyData {tcdCtxt = L ctxtL ctxt, tcdLName = tycon, 
			  tcdTyPats = Just typats, tcdCons = condecls,
			  tcdDerivs = derivs}) =
      do { checkM (null ctxt    ) $ addErr atNoCtxt	-- no context
         ; checkM (null condecls) $ addErr atNoCons	-- no constructors
	 -- check and collect type parameters
         ; let (idxParms, excessParms) = splitAt (length classLTyVars) typats
	 ; zipWithM_ cmpTyVar idxParms classLTyVars
	 ; excessTyVars <- liftM catMaybes $ mappM chkTyVar excessParms
	 -- bind excess parameters
	 ; bindTyVarsRn data_doc excessTyVars	$ \ excessTyVars' -> do {
	 ; tycon' <- lookupLocatedTopBndrRn tycon
	 ; (derivs', deriv_fvs) <- rn_derivs derivs
	 ; returnM (TyData {tcdND = tcdND tydecl, tcdCtxt = L ctxtL [], 
			    tcdLName = tycon', 
			    tcdTyVars = classLTyVars ++ excessTyVars',
			    tcdTyPats = Nothing, tcdKindSig = Nothing, 
			    tcdCons = [], tcdDerivs = derivs'}, 
		    delFVs (map hsLTyVarName (classLTyVars ++ excessTyVars')) $
	     	    deriv_fvs) } }
      where
	    -- Check that the name space is correct!
	cmpTyVar (L l ty@(HsTyVar tv)) classTV =      -- just a type variable
	  checkM (rdrNameOcc tv == nameOccName classTVName) $ 
	    mustMatchErr l ty classTVName
          where
	    classTVName = hsLTyVarName classTV
	cmpTyVar (L l ty@(HsKindSig (L _ (HsTyVar tv)) k)) _ | isRdrTyVar tv = 
	  noKindSigErr l tv   -- additional kind sig not allowed at class parms
	cmpTyVar (L l otherTy) _ = 
	  tyVarExpectedErr l  -- parameter must be a type variable

	    -- Check that the name space is correct!
	chkTyVar (L l (HsKindSig (L _ (HsTyVar tv)) k))
	  | isRdrTyVar tv      = return $ Just (L l (KindedTyVar tv k))
	chkTyVar (L l (HsTyVar tv))
	  | isRdrTyVar tv      = return $ Just (L l (UserTyVar tv))
	chkTyVar (L l otherTy) = tyVarExpectedErr l >> return Nothing
				 -- drop parameter; we stop after renaming anyways

        rn_derivs Nothing   = returnM (Nothing, emptyFVs)
        rn_derivs (Just ds) = do
			        ds' <- rnLHsTypes data_doc ds
				returnM (Just ds', extractHsTyNames_s ds')
    
        atNoCtxt = text "Associated data type declarations cannot have a context"
        atNoCons = text "Associated data type declarations cannot have any constructors"
        data_doc = text "In the data type declaration for" <+> quotes (ppr tycon)

noKindSigErr l ty =
  addErrAt l $
    sep [ptext SLIT("No kind signature allowed at copies of class parameters:"),
         nest 2 $ ppr ty]

mustMatchErr l ty classTV =
  addErrAt l $
    sep [ptext SLIT("Type variable"), quotes (ppr ty), 
	 ptext SLIT("must match corresponding class parameter"), 
	 quotes (ppr classTV)]

tyVarExpectedErr l = 
  addErrAt l (ptext SLIT("Type found where type variable expected"))
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\end{code}
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%*********************************************************
%*							*
		Splices
%*							*
%*********************************************************

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Note [Splices]
~~~~~~~~~~~~~~
Consider
	f = ...
	h = ...$(thing "f")...

The splice can expand into literally anything, so when we do dependency
analysis we must assume that it might mention 'f'.  So we simply treat
all locally-defined names as mentioned by any splice.  This is terribly
brutal, but I don't see what else to do.  For example, it'll mean
that every locally-defined thing will appear to be used, so no unused-binding
warnings.  But if we miss the dependency, then we might typecheck 'h' before 'f',
and that will crash the type checker because 'f' isn't in scope.

Currently, I'm not treating a splice as also mentioning every import,
which is a bit inconsistent -- but there are a lot of them.  We might
thereby get some bogus unused-import warnings, but we won't crash the
type checker.  Not very satisfactory really.

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\begin{code}
rnSplice :: HsSplice RdrName -> RnM (HsSplice Name, FreeVars)
rnSplice (HsSplice n expr)
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  = do	{ checkTH expr "splice"
	; loc  <- getSrcSpanM
	; [n'] <- newLocalsRn [L loc n]
	; (expr', fvs) <- rnLExpr expr

	-- Ugh!  See Note [Splices] above
	; lcl_rdr <- getLocalRdrEnv
	; gbl_rdr <- getGlobalRdrEnv
	; let gbl_names = mkNameSet [gre_name gre | gre <- globalRdrEnvElts gbl_rdr, 
						    isLocalGRE gre]
	      lcl_names = mkNameSet (occEnvElts lcl_rdr)

	; return (HsSplice n' expr', fvs `plusFV` lcl_names `plusFV` gbl_names) }
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#ifdef GHCI 
checkTH e what = returnM ()	-- OK
#else
checkTH e what 	-- Raise an error in a stage-1 compiler
  = addErr (vcat [ptext SLIT("Template Haskell") <+> text what <+>  
	          ptext SLIT("illegal in a stage-1 compiler"),
	          nest 2 (ppr e)])
#endif   
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\end{code}