TcRnDriver.lhs 45 KB
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% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcModule]{Typechecking a whole module}

\begin{code}
module TcRnDriver (
#ifdef GHCI
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	tcRnStmt, tcRnExpr, tcRnType,
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	tcRnLookupRdrName,
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	tcRnLookupName,
	tcRnGetInfo,
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	getModuleExports, 
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#endif
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	tcRnModule, 
	tcTopSrcDecls,
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	tcRnExtCore
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    ) where

#include "HsVersions.h"

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import IO
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#ifdef GHCI
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import {-# SOURCE #-} TcSplice ( tcSpliceDecls )
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#endif

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import DynFlags		( DynFlag(..), DynFlags(..), dopt, GhcMode(..) )
import StaticFlags	( opt_PprStyle_Debug )
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import HsSyn		( HsModule(..), HsExtCore(..), HsGroup(..), LHsDecl,
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			  SpliceDecl(..), HsBind(..), LHsBinds,
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			  emptyRdrGroup, emptyRnGroup, appendGroups, plusHsValBinds,
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			  nlHsApp, nlHsVar, pprLHsBinds )
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import RdrHsSyn		( findSplice )
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import PrelNames	( runMainIOName, rootMainKey, rOOT_MAIN, mAIN,
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			  main_RDR_Unqual )
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import RdrName		( RdrName, mkRdrUnqual, emptyGlobalRdrEnv )
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import TcHsSyn		( zonkTopDecls )
import TcExpr 		( tcInferRho )
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import TcRnMonad
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import TcType		( tidyTopType, tcEqType )
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import Inst		( showLIE )
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import InstEnv		( extendInstEnvList, Instance, pprInstances, instanceDFunId )
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import TcBinds		( tcTopBinds, tcHsBootSigs )
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import TcDefaults	( tcDefaults )
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import TcEnv		( tcExtendGlobalValEnv, iDFunId )
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import TcRules		( tcRules )
import TcForeign	( tcForeignImports, tcForeignExports )
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import TcInstDcls	( tcInstDecls1, tcInstDecls2 )
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import TcIface		( tcExtCoreBindings, tcHiBootIface )
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import IfaceSyn		( checkBootDecl, tyThingToIfaceDecl, IfaceExtName(..) )
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import TcSimplify	( tcSimplifyTop )
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import TcTyClsDecls	( tcTyAndClassDecls )
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import LoadIface	( loadOrphanModules )
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import RnNames		( importsFromLocalDecls, rnImports, rnExports,
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                          mkRdrEnvAndImports, mkExportNameSet,
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			  reportUnusedNames, reportDeprecations )
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import RnEnv		( lookupSrcOcc_maybe )
import RnSource		( rnSrcDecls, rnTyClDecls, checkModDeprec )
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import PprCore		( pprRules, pprCoreBindings )
import CoreSyn		( CoreRule, bindersOfBinds )
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import ErrUtils		( Messages, mkDumpDoc, showPass )
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import Id		( Id, mkExportedLocalId, isLocalId, idName, idType )
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import Var		( Var )
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import Module
import UniqFM		( elemUFM, eltsUFM )
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import OccName		( mkVarOccFS, plusOccEnv )
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import Name		( Name, NamedThing(..), isExternalName, getSrcLoc, isWiredInName,
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			  nameModule, nameOccName, isImplicitName, mkExternalName )
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import NameSet
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import TyCon		( tyConHasGenerics )
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import SrcLoc		( srcLocSpan, Located(..), noLoc )
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import DriverPhases	( HscSource(..), isHsBoot )
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import HscTypes		( ModGuts(..), ModDetails(..), emptyModDetails,
			  HscEnv(..), ExternalPackageState(..),
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			  IsBootInterface, noDependencies, 
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			  Deprecs( NoDeprecs ), plusDeprecs,
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			  ForeignStubs(NoStubs), 
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			  TypeEnv, lookupTypeEnv, hptInstances, 
			  extendTypeEnvWithIds, typeEnvIds, typeEnvTyCons, typeEnvElts,
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			  emptyFixityEnv
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			)
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import Outputable

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#ifdef GHCI
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import HsSyn		( HsStmtContext(..), Stmt(..), HsExpr(..), 
			  HsLocalBinds(..), HsValBinds(..),
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			  LStmt, LHsExpr, LHsType, mkMatch, emptyLocalBinds,
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			  collectLStmtsBinders, collectLStmtBinders, nlVarPat,
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		   	  mkFunBind, placeHolderType, noSyntaxExpr )
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import RdrName		( GlobalRdrElt(..), globalRdrEnvElts,
			  unQualOK, lookupLocalRdrEnv, extendLocalRdrEnv )
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import RnSource		( addTcgDUs )
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import TcHsSyn		( mkHsDictLet, zonkTopLExpr, zonkTopBndrs )
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import TcHsType		( kcHsType )
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import TcMType		( zonkTcType, zonkQuantifiedTyVar )
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import TcMatches	( tcStmts, tcDoStmt )
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import TcSimplify	( tcSimplifyInteractive, tcSimplifyInfer )
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import TcType		( Type, mkForAllTys, mkFunTys, mkTyConApp, tyVarsOfType, isTauTy,
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			  isUnLiftedType, tyClsNamesOfDFunHead, tyClsNamesOfType, isUnitTy )
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import TcEnv		( tcLookupTyCon, tcLookupId, tcLookupGlobal )
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import TypeRep		( TyThing(..) )
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import RnTypes		( rnLHsType )
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import Inst		( tcGetInstEnvs )
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import InstEnv		( classInstances, instEnvElts )
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import RnExpr		( rnStmts, rnLExpr )
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import LoadIface	( loadSysInterface )
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import IfaceEnv		( ifaceExportNames )
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import RnEnv		( lookupOccRn, dataTcOccs, lookupFixityRn )
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import Id		( setIdType )
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import MkId		( unsafeCoerceId )
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import TyCon		( tyConName )
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import TysWiredIn	( mkListTy, unitTy )
import IdInfo		( GlobalIdDetails(..) )
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import Kind		( Kind )
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import Var		( globaliseId )
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import Name		( isBuiltInSyntax, isInternalName )
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import OccName		( isTcOcc )
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import NameEnv		( delListFromNameEnv )
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import PrelNames	( iNTERACTIVE, ioTyConName, printName, itName, 
			  bindIOName, thenIOName, returnIOName )
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import HscTypes		( InteractiveContext(..),
			  ModIface(..), icPrintUnqual,
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			  Dependencies(..) )
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import BasicTypes	( Fixity, RecFlag(..) )
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import SrcLoc		( unLoc )
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#endif

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import FastString	( mkFastString )
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import Util		( sortLe )
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import Bag		( unionBags, snocBag, emptyBag, unitBag, unionManyBags )
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import Data.Maybe	( isJust, isNothing )
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\end{code}



%************************************************************************
%*									*
	Typecheck and rename a module
%*									*
%************************************************************************


\begin{code}
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tcRnModule :: HscEnv 
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	   -> HscSource
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	   -> Bool 		-- True <=> save renamed syntax
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	   -> Located (HsModule RdrName)
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	   -> IO (Messages, Maybe TcGblEnv)
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tcRnModule hsc_env hsc_src save_rn_syntax
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	 (L loc (HsModule maybe_mod export_ies 
			  import_decls local_decls mod_deprec))
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 = do { showPass (hsc_dflags hsc_env) "Renamer/typechecker" ;

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   let { this_pkg = thisPackage (hsc_dflags hsc_env) ;
	 this_mod = case maybe_mod of
			Nothing  -> mAIN	-- 'module M where' is omitted
			Just (L _ mod) -> mkModule this_pkg mod } ;
						-- The normal case
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   initTc hsc_env hsc_src this_mod $ 
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   setSrcSpan loc $
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   do {
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		-- Deal with imports;
	rn_imports <- rnImports import_decls ;
        (rdr_env, imports) <- mkRdrEnvAndImports rn_imports ;
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	let { dep_mods :: ModuleNameEnv (ModuleName, IsBootInterface)
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	    ; dep_mods = imp_dep_mods imports

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		-- We want instance declarations from all home-package
		-- modules below this one, including boot modules, except
		-- ourselves.  The 'except ourselves' is so that we don't
		-- get the instances from this module's hs-boot file
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	    ; want_instances :: ModuleName -> Bool
	    ; want_instances mod = mod `elemUFM` dep_mods
				   && mod /= moduleName this_mod
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	    ; home_insts = hptInstances hsc_env want_instances
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	    } ;

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		-- Record boot-file info in the EPS, so that it's 
		-- visible to loadHiBootInterface in tcRnSrcDecls,
		-- and any other incrementally-performed imports
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	updateEps_ (\eps -> eps { eps_is_boot = dep_mods }) ;
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		-- Update the gbl env
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	updGblEnv ( \ gbl -> 
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		gbl { tcg_rdr_env  = plusOccEnv (tcg_rdr_env gbl) rdr_env,
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		      tcg_inst_env = extendInstEnvList (tcg_inst_env gbl) home_insts,
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		      tcg_imports  = tcg_imports gbl `plusImportAvails` imports,
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                      tcg_rn_imports = if save_rn_syntax then
                                         Just rn_imports
                                       else
                                         Nothing,
		      tcg_rn_decls = if save_rn_syntax then
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					Just emptyRnGroup
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				     else
					Nothing })
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		$ do {

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	traceRn (text "rn1" <+> ppr (imp_dep_mods imports)) ;
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		-- Fail if there are any errors so far
		-- The error printing (if needed) takes advantage 
		-- of the tcg_env we have now set
	failIfErrsM ;

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		-- Load any orphan-module interfaces, so that
		-- their rules and instance decls will be found
	loadOrphanModules (imp_orphs imports) ;

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	traceRn (text "rn1a") ;
		-- Rename and type check the declarations
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	tcg_env <- if isHsBoot hsc_src then
			tcRnHsBootDecls local_decls
		   else	
			tcRnSrcDecls local_decls ;
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	setGblEnv tcg_env		$ do {

	traceRn (text "rn3") ;

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		-- Report the use of any deprecated things
		-- We do this before processsing the export list so
		-- that we don't bleat about re-exporting a deprecated
		-- thing (especially via 'module Foo' export item)
		-- Only uses in the body of the module are complained about
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	reportDeprecations (hsc_dflags hsc_env) tcg_env ;
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		-- Process the export list
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	rn_exports <- rnExports export_ies ;
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        let { liftM2' fn a b = do a' <- a; b' <- b; return (fn a' b') } ;
        exports <- mkExportNameSet (isJust maybe_mod) (liftM2' (,) rn_exports export_ies) ;
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		-- Check whether the entire module is deprecated
		-- This happens only once per module
	let { mod_deprecs = checkModDeprec mod_deprec } ;

		-- Add exports and deprecations to envt
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	let { final_env  = tcg_env { tcg_exports = exports,
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                                     tcg_rn_exports = if save_rn_syntax then
                                                         rn_exports
                                                      else Nothing,
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				     tcg_dus = tcg_dus tcg_env `plusDU` usesOnly exports,
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				     tcg_deprecs = tcg_deprecs tcg_env `plusDeprecs` 
						   mod_deprecs }
		-- A module deprecation over-rides the earlier ones
	     } ;
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		-- Report unused names
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 	reportUnusedNames export_ies final_env ;
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		-- Dump output and return
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	tcDump final_env ;
	return final_env
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    }}}}
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\end{code}


%************************************************************************
%*									*
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	Type-checking external-core modules
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%*									*
%************************************************************************

\begin{code}
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tcRnExtCore :: HscEnv 
	    -> HsExtCore RdrName
	    -> IO (Messages, Maybe ModGuts)
	-- Nothing => some error occurred 
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tcRnExtCore hsc_env (HsExtCore this_mod decls src_binds)
	-- The decls are IfaceDecls; all names are original names
 = do { showPass (hsc_dflags hsc_env) "Renamer/typechecker" ;
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   initTc hsc_env ExtCoreFile this_mod $ do {
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   let { ldecls  = map noLoc decls } ;
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	-- Deal with the type declarations; first bring their stuff
	-- into scope, then rname them, then type check them
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   tcg_env  <- importsFromLocalDecls (mkFakeGroup ldecls) ;
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   setGblEnv tcg_env $ do {
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   rn_decls <- rnTyClDecls ldecls ;
   failIfErrsM ;
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	-- Dump trace of renaming part
   rnDump (ppr rn_decls) ;
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	-- Typecheck them all together so that
	-- any mutually recursive types are done right
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   tcg_env <- checkNoErrs (tcTyAndClassDecls emptyModDetails rn_decls) ;
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	-- Make the new type env available to stuff slurped from interface files
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   setGblEnv tcg_env $ do {
   
	-- Now the core bindings
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   core_binds <- initIfaceExtCore (tcExtCoreBindings src_binds) ;
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	-- Wrap up
   let {
	bndrs 	   = bindersOfBinds core_binds ;
	my_exports = mkNameSet (map idName bndrs) ;
		-- ToDo: export the data types also?
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	final_type_env = extendTypeEnvWithIds (tcg_type_env tcg_env) bndrs ;
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	mod_guts = ModGuts {	mg_module   = this_mod,
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				mg_boot	    = False,
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				mg_usages   = [],		-- ToDo: compute usage
				mg_dir_imps = [],		-- ??
				mg_deps     = noDependencies,	-- ??
				mg_exports  = my_exports,
				mg_types    = final_type_env,
				mg_insts    = tcg_insts tcg_env,
				mg_rules    = [],
				mg_binds    = core_binds,
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				-- Stubs
				mg_rdr_env  = emptyGlobalRdrEnv,
				mg_fix_env  = emptyFixityEnv,
				mg_deprecs  = NoDeprecs,
				mg_foreign  = NoStubs
		    } } ;
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   tcCoreDump mod_guts ;
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   return mod_guts
   }}}}
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mkFakeGroup decls -- Rather clumsy; lots of unused fields
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  = emptyRdrGroup { hs_tyclds = decls }
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\end{code}
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%************************************************************************
%*									*
	Type-checking the top level of a module
%*									*
%************************************************************************
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\begin{code}
tcRnSrcDecls :: [LHsDecl RdrName] -> TcM TcGblEnv
	-- Returns the variables free in the decls
	-- Reason: solely to report unused imports and bindings
tcRnSrcDecls decls
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 = do { 	-- Load the hi-boot interface for this module, if any
		-- We do this now so that the boot_names can be passed
		-- to tcTyAndClassDecls, because the boot_names are 
		-- automatically considered to be loop breakers
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	mod <- getModule ;
	boot_iface <- tcHiBootIface mod ;
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	  	-- Do all the declarations
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	(tc_envs, lie) <- getLIE (tc_rn_src_decls boot_iface decls) ;
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	     -- tcSimplifyTop deals with constant or ambiguous InstIds.  
	     -- How could there be ambiguous ones?  They can only arise if a
	     -- top-level decl falls under the monomorphism
	     -- restriction, and no subsequent decl instantiates its
	     -- type.  (Usually, ambiguous type variables are resolved
	     -- during the generalisation step.)
        traceTc (text "Tc8") ;
	inst_binds <- setEnvs tc_envs (tcSimplifyTop lie) ;
		-- Setting the global env exposes the instances to tcSimplifyTop
		-- Setting the local env exposes the local Ids to tcSimplifyTop, 
		-- so that we get better error messages (monomorphism restriction)
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	    -- Backsubstitution.  This must be done last.
	    -- Even tcSimplifyTop may do some unification.
        traceTc (text "Tc9") ;
	let { (tcg_env, _) = tc_envs ;
	      TcGblEnv { tcg_type_env = type_env, tcg_binds = binds, 
		         tcg_rules = rules, tcg_fords = fords } = tcg_env } ;
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	tcDump tcg_env ;
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	(bind_ids, binds', fords', rules') <- zonkTopDecls (binds `unionBags` inst_binds)
							   rules fords ;
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	let { final_type_env = extendTypeEnvWithIds type_env bind_ids
	    ; tcg_env' = tcg_env { tcg_type_env = final_type_env,
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			 	   tcg_binds = binds',
				   tcg_rules = rules', 
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				   tcg_fords = fords' } } ;
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	-- Make the new type env available to stuff slurped from interface files
	writeMutVar (tcg_type_env_var tcg_env) final_type_env ;
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	-- Compare the hi-boot iface (if any) with the real thing
 	dfun_binds <- checkHiBootIface tcg_env' boot_iface ;

	return (tcg_env' { tcg_binds = tcg_binds tcg_env' `unionBags` dfun_binds }) 
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   }
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tc_rn_src_decls :: ModDetails -> [LHsDecl RdrName] -> TcM (TcGblEnv, TcLclEnv)
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-- Loops around dealing with each top level inter-splice group 
-- in turn, until it's dealt with the entire module
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tc_rn_src_decls boot_details ds
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 = do { let { (first_group, group_tail) = findSplice ds } ;
		-- If ds is [] we get ([], Nothing)
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	-- Type check the decls up to, but not including, the first splice
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	tc_envs@(tcg_env,tcl_env) <- tcRnGroup boot_details first_group ;
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	-- Bale out if errors; for example, error recovery when checking
	-- the RHS of 'main' can mean that 'main' is not in the envt for 
	-- the subsequent checkMain test
	failIfErrsM ;
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	setEnvs tc_envs $

	-- If there is no splice, we're nearly done
	case group_tail of {
	   Nothing -> do { 	-- Last thing: check for `main'
			   tcg_env <- checkMain ;
			   return (tcg_env, tcl_env) 
		      } ;

	-- If there's a splice, we must carry on
	   Just (SpliceDecl splice_expr, rest_ds) -> do {
#ifndef GHCI
	failWithTc (text "Can't do a top-level splice; need a bootstrapped compiler")
#else

	-- Rename the splice expression, and get its supporting decls
	(rn_splice_expr, splice_fvs) <- rnLExpr splice_expr ;
	failIfErrsM ;	-- Don't typecheck if renaming failed

	-- Execute the splice
	spliced_decls <- tcSpliceDecls rn_splice_expr ;

	-- Glue them on the front of the remaining decls and loop
	setGblEnv (tcg_env `addTcgDUs` usesOnly splice_fvs) $
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	tc_rn_src_decls boot_details (spliced_decls ++ rest_ds)
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#endif /* GHCI */
    }}}
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\end{code}

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%************************************************************************
%*									*
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	Compiling hs-boot source files, and
	comparing the hi-boot interface with the real thing
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%*									*
%************************************************************************

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\begin{code}
tcRnHsBootDecls :: [LHsDecl RdrName] -> TcM TcGblEnv
tcRnHsBootDecls decls
   = do { let { (first_group, group_tail) = findSplice decls }

	; case group_tail of
	     Just stuff -> spliceInHsBootErr stuff
	     Nothing    -> return ()

		-- Rename the declarations
	; (tcg_env, rn_group) <- rnTopSrcDecls first_group
	; setGblEnv tcg_env $ do {

	-- Todo: check no foreign decls, no rules, no default decls

		-- Typecheck type/class decls
	; traceTc (text "Tc2")
	; let tycl_decls = hs_tyclds rn_group
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	; tcg_env <- checkNoErrs (tcTyAndClassDecls emptyModDetails tycl_decls)
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	; setGblEnv tcg_env	$ do {

		-- Typecheck instance decls
	; traceTc (text "Tc3")
	; (tcg_env, inst_infos, _binds) <- tcInstDecls1 tycl_decls (hs_instds rn_group)
	; setGblEnv tcg_env	$ do {

		-- Typecheck value declarations
	; traceTc (text "Tc5") 
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	; val_ids <- tcHsBootSigs (hs_valds rn_group)
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		-- Wrap up
		-- No simplification or zonking to do
	; traceTc (text "Tc7a")
	; gbl_env <- getGblEnv 
	
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		-- Make the final type-env
		-- Include the dfun_ids so that their type sigs get
		-- are written into the interface file
	; let { type_env0 = tcg_type_env gbl_env
	      ; type_env1 = extendTypeEnvWithIds type_env0 val_ids
	      ; type_env2 = extendTypeEnvWithIds type_env1 dfun_ids 
	      ; dfun_ids = map iDFunId inst_infos }
	; return (gbl_env { tcg_type_env = type_env2 }) 
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   }}}}

spliceInHsBootErr (SpliceDecl (L loc _), _)
  = addErrAt loc (ptext SLIT("Splices are not allowed in hs-boot files"))
\end{code}

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Once we've typechecked the body of the module, we want to compare what
we've found (gathered in a TypeEnv) with the hi-boot details (if any).
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\begin{code}
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checkHiBootIface :: TcGblEnv -> ModDetails -> TcM (LHsBinds Id)
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-- Compare the hi-boot file for this module (if there is one)
-- with the type environment we've just come up with
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-- In the common case where there is no hi-boot file, the list
-- of boot_names is empty.
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509
--
-- The bindings we return give bindings for the dfuns defined in the
-- hs-boot file, such as 	$fbEqT = $fEqT

510
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512
checkHiBootIface
	(TcGblEnv { tcg_insts = local_insts, tcg_type_env = local_type_env })
	(ModDetails { md_insts = boot_insts, md_types = boot_type_env })
513
514
  = do	{ traceTc (text "checkHiBootIface" <+> (ppr boot_type_env $$ ppr boot_insts)) ;
	; mapM_ check_one (typeEnvElts boot_type_env)
515
516
	; dfun_binds <- mapM check_inst boot_insts
	; return (unionManyBags dfun_binds) }
517
518
519
520
  where
    check_one boot_thing
      | no_check name
      = return ()	
521
522
523
524
525
526
527
528
529
      | Just real_thing <- lookupTypeEnv local_type_env name
      = do { let boot_decl = tyThingToIfaceDecl ext_nm boot_thing
	         real_decl = tyThingToIfaceDecl ext_nm real_thing
	   ; checkTc (checkBootDecl boot_decl real_decl)
		     (bootMisMatch boot_thing boot_decl real_decl) }
		-- The easiest way to check compatibility is to convert to
		-- iface syntax, where we already have good comparison functions
      | otherwise
      = addErrTc (missingBootThing boot_thing)
530
531
532
      where
	name = getName boot_thing

533
534
535
    ext_nm name = ExtPkg (nameModule name) (nameOccName name)
	-- Just enough to compare; no versions etc needed

536
537
538
539
    no_check name = isWiredInName name	-- No checking for wired-in names.  In particular,
					-- 'error' is handled by a rather gross hack
					-- (see comments in GHC.Err.hs-boot)
		  || name `elem` dfun_names
540
541
		  || isImplicitName name	-- Has a parent, which we'll check

542
543
    dfun_names = map getName boot_insts

544
545
546
547
548
    check_inst boot_inst
	= case [dfun | inst <- local_insts, 
		       let dfun = instanceDFunId inst,
		       idType dfun `tcEqType` boot_inst_ty ] of
	    [] -> do { addErrTc (instMisMatch boot_inst); return emptyBag }
549
	    (dfun:_) -> return (unitBag $ noLoc $ VarBind local_boot_dfun (nlHsVar dfun))
550
551
552
	where
	  boot_dfun = instanceDFunId boot_inst
	  boot_inst_ty = idType boot_dfun
553
	  local_boot_dfun = mkExportedLocalId (idName boot_dfun) boot_inst_ty
554
555
556

----------------
missingBootThing thing
557
  = ppr thing <+> ptext SLIT("is defined in the hs-boot file, but not in the module")
558
bootMisMatch thing boot_decl real_decl
559
  = ppr thing <+> ptext SLIT("has conflicting definitions in the module and its hs-boot file")
560
instMisMatch inst
561
  = hang (ppr inst)
562
       2 (ptext SLIT("is defined in the hs-boot file, but not in the module"))
563
564
\end{code}

565

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570
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573
574
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576
577
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579
580
581
%************************************************************************
%*									*
	Type-checking the top level of a module
%*									*
%************************************************************************

tcRnGroup takes a bunch of top-level source-code declarations, and
 * renames them
 * gets supporting declarations from interface files
 * typechecks them
 * zonks them
 * and augments the TcGblEnv with the results

In Template Haskell it may be called repeatedly for each group of
declarations.  It expects there to be an incoming TcGblEnv in the
monad; it augments it and returns the new TcGblEnv.
582
583

\begin{code}
584
tcRnGroup :: ModDetails -> HsGroup RdrName -> TcM (TcGblEnv, TcLclEnv)
585
	-- Returns the variables free in the decls, for unused-binding reporting
586
tcRnGroup boot_details decls
587
588
589
 = do {		-- Rename the declarations
	(tcg_env, rn_decls) <- rnTopSrcDecls decls ;
	setGblEnv tcg_env $ do {
590

591
		-- Typecheck the declarations
592
	tcTopSrcDecls boot_details rn_decls 
593
  }}
594

595
596
597
598
------------------------------------------------
rnTopSrcDecls :: HsGroup RdrName -> TcM (TcGblEnv, HsGroup Name)
rnTopSrcDecls group
 = do { 	-- Bring top level binders into scope
599
600
	tcg_env <- importsFromLocalDecls group ;
	setGblEnv tcg_env $ do {
601

602
	failIfErrsM ;	-- No point in continuing if (say) we have duplicate declarations
603

604
605
606
		-- Rename the source decls
	(tcg_env, rn_decls) <- rnSrcDecls group ;
	failIfErrsM ;
607

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610
611
612
613
614
		-- save the renamed syntax, if we want it
	let { tcg_env'
	        | Just grp <- tcg_rn_decls tcg_env
	          = tcg_env{ tcg_rn_decls = Just (appendGroups grp rn_decls) }
	        | otherwise
	           = tcg_env };

615
616
		-- Dump trace of renaming part
	rnDump (ppr rn_decls) ;
617

618
	return (tcg_env', rn_decls)
619
   }}
620

621
------------------------------------------------
622
623
tcTopSrcDecls :: ModDetails -> HsGroup Name -> TcM (TcGblEnv, TcLclEnv)
tcTopSrcDecls boot_details
624
625
626
627
628
629
630
631
632
	(HsGroup { hs_tyclds = tycl_decls, 
		   hs_instds = inst_decls,
		   hs_fords  = foreign_decls,
		   hs_defds  = default_decls,
		   hs_ruleds = rule_decls,
		   hs_valds  = val_binds })
 = do {		-- Type-check the type and class decls, and all imported decls
		-- The latter come in via tycl_decls
        traceTc (text "Tc2") ;
633

634
	tcg_env <- checkNoErrs (tcTyAndClassDecls boot_details tycl_decls) ;
635
636
637
638
639
	-- tcTyAndClassDecls recovers internally, but if anything gave rise to
	-- an error we'd better stop now, to avoid a cascade
	
	-- Make these type and class decls available to stuff slurped from interface files
	writeMutVar (tcg_type_env_var tcg_env) (tcg_type_env tcg_env) ;
640
641


642
643
644
645
646
647
	setGblEnv tcg_env	$ do {
		-- Source-language instances, including derivings,
		-- and import the supporting declarations
        traceTc (text "Tc3") ;
	(tcg_env, inst_infos, deriv_binds) <- tcInstDecls1 tycl_decls inst_decls ;
	setGblEnv tcg_env	$ do {
648

649
650
651
652
653
	        -- Foreign import declarations next.  No zonking necessary
		-- here; we can tuck them straight into the global environment.
        traceTc (text "Tc4") ;
	(fi_ids, fi_decls) <- tcForeignImports foreign_decls ;
	tcExtendGlobalValEnv fi_ids	$ do {
654

655
656
657
658
		-- Default declarations
        traceTc (text "Tc4a") ;
	default_tys <- tcDefaults default_decls ;
	updGblEnv (\gbl -> gbl { tcg_default = default_tys }) $ do {
659
	
660
661
662
663
		-- Value declarations next
		-- We also typecheck any extra binds that came out 
		-- of the "deriving" process (deriv_binds)
        traceTc (text "Tc5") ;
664
	(tc_val_binds, tcl_env) <- tcTopBinds (val_binds `plusHsValBinds` deriv_binds) ;
665
	setLclTypeEnv tcl_env 	$ do {
666

667
668
	     	-- Second pass over class and instance declarations, 
        traceTc (text "Tc6") ;
669
	(inst_binds, tcl_env) <- tcInstDecls2 tycl_decls inst_infos ;
670
	showLIE (text "after instDecls2") ;
671

672
673
674
675
		-- Foreign exports
		-- They need to be zonked, so we return them
        traceTc (text "Tc7") ;
	(foe_binds, foe_decls) <- tcForeignExports foreign_decls ;
676

677
678
		-- Rules
	rules <- tcRules rule_decls ;
679

680
681
682
683
684
685
686
687
688
689
690
691
		-- Wrap up
        traceTc (text "Tc7a") ;
	tcg_env <- getGblEnv ;
	let { all_binds = tc_val_binds	 `unionBags`
			  inst_binds	 `unionBags`
			  foe_binds  ;

		-- Extend the GblEnv with the (as yet un-zonked) 
		-- bindings, rules, foreign decls
	      tcg_env' = tcg_env {  tcg_binds = tcg_binds tcg_env `unionBags` all_binds,
				    tcg_rules = tcg_rules tcg_env ++ rules,
				    tcg_fords = tcg_fords tcg_env ++ foe_decls ++ fi_decls } } ;
692
  	return (tcg_env', tcl_env)
693
    }}}}}}
694
695
\end{code}

696

697
698
%************************************************************************
%*									*
699
	Checking for 'main'
700
701
702
703
%*									*
%************************************************************************

\begin{code}
704
705
checkMain :: TcM TcGblEnv
-- If we are in module Main, check that 'main' is defined.
706
checkMain 
707
  = do { ghc_mode <- getGhcMode ;
708
	 tcg_env   <- getGblEnv ;
709
	 dflags    <- getDOpts ;
710
	 let { main_mod = mainModIs dflags ;
711
	       main_fn  = case mainFunIs dflags of {
712
				Just fn -> mkRdrUnqual (mkVarOccFS (mkFastString fn)) ;
713
714
				Nothing -> main_RDR_Unqual } } ;
	
715
	 check_main ghc_mode tcg_env main_mod main_fn
716
    }
717

718

719
check_main ghc_mode tcg_env main_mod main_fn
720
 | mod /= main_mod
721
722
 = traceTc (text "checkMain not" <+> ppr main_mod <+> ppr mod) >>
   return tcg_env
723

724
725
726
727
728
729
 | otherwise
 = addErrCtxt mainCtxt			$
   do	{ mb_main <- lookupSrcOcc_maybe main_fn
		-- Check that 'main' is in scope
		-- It might be imported from another module!
	; case mb_main of {
730
731
	     Nothing -> do { traceTc (text "checkMain fail" <+> ppr main_mod <+> ppr main_fn)
			   ; complain_no_main	
732
733
			   ; return tcg_env } ;
	     Just main_name -> do
734
735
	{ traceTc (text "checkMain found" <+> ppr main_mod <+> ppr main_fn)
	; let { rhs = nlHsApp (nlHsVar runMainIOName) (nlHsVar main_name) }
736
		   	-- :Main.main :: IO () = runMainIO main 
737

738
	; (main_expr, ty) <- setSrcSpan (srcLocSpan (getSrcLoc main_name)) $
739
			     tcInferRho rhs
740

741
742
743
744
745
746
747
748
749
750
751
752
753
	-- The function that the RTS invokes is always :Main.main,
	-- which we call root_main_id.  
	-- (Because GHC allows the user to have a module not called 
	-- Main as the main module, we can't rely on the main function
	-- being called "Main.main".  That's why root_main_id has a fixed
	-- module ":Main".)
	-- We also make root_main_id an implicit Id, by making main_name
	-- its parent (hence (Just main_name)).  That has the effect
	-- of preventing its type and unfolding from getting out into
	-- the interface file. Otherwise we can end up with two defns
	-- for 'main' in the interface file!

	; let { root_main_name =  mkExternalName rootMainKey rOOT_MAIN 
754
				   (mkVarOccFS FSLIT("main")) 
755
756
757
				   (Just main_name) (getSrcLoc main_name)
	      ; root_main_id = mkExportedLocalId root_main_name ty
	      ; main_bind    = noLoc (VarBind root_main_id main_expr) }
758

759
760
761
762
	; return (tcg_env { tcg_binds = tcg_binds tcg_env 
					`snocBag` main_bind,
			    tcg_dus   = tcg_dus tcg_env
				        `plusDU` usesOnly (unitFV main_name)
763
764
			-- Record the use of 'main', so that we don't 
			-- complain about it being defined but not used
765
766
767
		 }) 
    }}}
  where
768
    mod = tcg_mod tcg_env
769
 
770
    complain_no_main | ghc_mode == Interactive = return ()
771
772
773
774
		     | otherwise 		= failWithTc noMainMsg
	-- In interactive mode, don't worry about the absence of 'main'
	-- In other modes, fail altogether, so that we don't go on
	-- and complain a second time when processing the export list.
775

776
777
778
779
    mainCtxt  = ptext SLIT("When checking the type of the main function") <+> quotes (ppr main_fn)
    noMainMsg = ptext SLIT("The main function") <+> quotes (ppr main_fn) 
		<+> ptext SLIT("is not defined in module") <+> quotes (ppr main_mod)
\end{code}
780

781
782
783
784
785
%*********************************************************
%*						 	 *
		GHCi stuff
%*							 *
%*********************************************************
786

787
788
\begin{code}
#ifdef GHCI
789
790
791
setInteractiveContext :: HscEnv -> InteractiveContext -> TcRn a -> TcRn a
setInteractiveContext hsc_env icxt thing_inside 
  = let 
792
793
794
795
	-- Initialise the tcg_inst_env with instances 
	-- from all home modules.  This mimics the more selective
	-- call to hptInstances in tcRnModule
	dfuns = hptInstances hsc_env (\mod -> True)
796
797
798
799
800
801
802
803
804
805
    in
    updGblEnv (\env -> env { 
	tcg_rdr_env  = ic_rn_gbl_env icxt,
	tcg_type_env = ic_type_env   icxt,
	tcg_inst_env = extendInstEnvList (tcg_inst_env env) dfuns }) $

    updLclEnv (\env -> env { tcl_rdr = ic_rn_local_env icxt })	$

    do	{ traceTc (text "setIC" <+> ppr (ic_type_env icxt))
 	; thing_inside }
806
\end{code}
807

808

809
810
811
812
813
814
815
816
817
818
\begin{code}
tcRnStmt :: HscEnv
	 -> InteractiveContext
	 -> LStmt RdrName
	 -> IO (Maybe (InteractiveContext, [Name], LHsExpr Id))
		-- The returned [Name] is the same as the input except for
		-- ExprStmt, in which case the returned [Name] is [itName]
		--
		-- The returned TypecheckedHsExpr is of type IO [ () ],
		-- a list of the bound values, coerced to ().
819

820
821
tcRnStmt hsc_env ictxt rdr_stmt
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
822
    setInteractiveContext hsc_env ictxt $ do {
823

824
    -- Rename; use CmdLineMode because tcRnStmt is only used interactively
825
    (([rn_stmt], _), fvs) <- rnStmts DoExpr [rdr_stmt] (return ((), emptyFVs)) ;
826
827
828
829
    traceRn (text "tcRnStmt" <+> vcat [ppr rdr_stmt, ppr rn_stmt, ppr fvs]) ;
    failIfErrsM ;
    
    -- The real work is done here
830
831
832
    (bound_ids, tc_expr) <- mkPlan rn_stmt ;
    zonked_expr <- zonkTopLExpr tc_expr ;
    zonked_ids  <- zonkTopBndrs bound_ids ;
833
    
834
835
836
837
	-- None of the Ids should be of unboxed type, because we
	-- cast them all to HValues in the end!
    mappM bad_unboxed (filter (isUnLiftedType . idType) zonked_ids) ;

838
    traceTc (text "tcs 1") ;
839
840
841
842
843
844
845
846
847
    let {	-- (a) Make all the bound ids "global" ids, now that
    		--     they're notionally top-level bindings.  This is
	    	--     important: otherwise when we come to compile an expression
	    	--     using these ids later, the byte code generator will consider
	    	--     the occurrences to be free rather than global.
		-- 
		-- (b) Tidy their types; this is important, because :info may
		--     ask to look at them, and :info expects the things it looks
		--     up to have tidy types
848
	global_ids = map globaliseAndTidy zonked_ids ;
849
850
851
852
    
		-- Update the interactive context
	rn_env   = ic_rn_local_env ictxt ;
	type_env = ic_type_env ictxt ;
853

854
855
	bound_names = map idName global_ids ;
	new_rn_env  = extendLocalRdrEnv rn_env bound_names ;
856

857
858
859
860
861
862
		-- Remove any shadowed bindings from the type_env;
		-- they are inaccessible but might, I suppose, cause 
		-- a space leak if we leave them there
	shadowed = [ n | name <- bound_names,
			 let rdr_name = mkRdrUnqual (nameOccName name),
			 Just n <- [lookupLocalRdrEnv rn_env rdr_name] ] ;
863

864
865
	filtered_type_env = delListFromNameEnv type_env shadowed ;
	new_type_env = extendTypeEnvWithIds filtered_type_env global_ids ;
866

867
868
869
	new_ic = ictxt { ic_rn_local_env = new_rn_env, 
		  	 ic_type_env     = new_type_env }
    } ;
870

871
872
    dumpOptTcRn Opt_D_dump_tc 
    	(vcat [text "Bound Ids" <+> pprWithCommas ppr global_ids,
873
    	       text "Typechecked expr" <+> ppr zonked_expr]) ;
874

875
    returnM (new_ic, bound_names, zonked_expr)
876
    }
877
878
879
  where
    bad_unboxed id = addErr (sep [ptext SLIT("GHCi can't bind a variable of unlifted type:"),
				  nest 2 (ppr id <+> dcolon <+> ppr (idType id))])
880

881
882
883
884
885
886
887
globaliseAndTidy :: Id -> Id
globaliseAndTidy id
-- Give the Id a Global Name, and tidy its type
  = setIdType (globaliseId VanillaGlobal id) tidy_type
  where
    tidy_type = tidyTopType (idType id)
\end{code}
888

889
Here is the grand plan, implemented in tcUserStmt
890

891
892
893
894
	What you type			The IO [HValue] that hscStmt returns
	-------------			------------------------------------
	let pat = expr		==> 	let pat = expr in return [coerce HVal x, coerce HVal y, ...]
					bindings: [x,y,...]
895

896
897
	pat <- expr		==> 	expr >>= \ pat -> return [coerce HVal x, coerce HVal y, ...]
					bindings: [x,y,...]
898

899
900
901
902
903
	expr (of IO type)	==>	expr >>= \ it -> return [coerce HVal it]
	  [NB: result not printed]	bindings: [it]
	  
	expr (of non-IO type,	==>	let it = expr in print it >> return [coerce HVal it]
	  result showable)		bindings: [it]
904

905
906
	expr (of non-IO type, 
	  result not showable)	==>	error
907

908

909
910
\begin{code}
---------------------------
911
912
913
914
915
916
917
918
919
920
921
922
type PlanResult = ([Id], LHsExpr Id)
type Plan = TcM PlanResult

runPlans :: [Plan] -> TcM PlanResult
-- Try the plans in order.  If one fails (by raising an exn), try the next.
-- If one succeeds, take it.
runPlans []     = panic "runPlans"
runPlans [p]    = p
runPlans (p:ps) = tryTcLIE_ (runPlans ps) p

--------------------
mkPlan :: LStmt Name -> TcM PlanResult
923
924
mkPlan (L loc (ExprStmt expr _ _))	-- An expression typed at the prompt 
  = do	{ uniq <- newUnique		-- is treated very specially
925
	; let fresh_it  = itName uniq
926
927
	      the_bind  = L loc $ mkFunBind (L loc fresh_it) matches
	      matches   = [mkMatch [] expr emptyLocalBinds]
928
	      let_stmt  = L loc $ LetStmt (HsValBinds (ValBindsOut [(NonRecursive,unitBag the_bind)] []))
929
930
931
932
933
934
935
936
937
	      bind_stmt = L loc $ BindStmt (nlVarPat fresh_it) expr
					   (HsVar bindIOName) noSyntaxExpr 
	      print_it  = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar fresh_it))
			          	   (HsVar thenIOName) placeHolderType

	-- The plans are:
	--	[it <- e; print it]	but not if it::()
	--	[it <- e]		
	--	[let it = e; print it]	
938
939
	; runPlans [	-- Plan A
		    do { stuff@([it_id], _) <- tcGhciStmts [bind_stmt, print_it]
940
941
942
		       ; it_ty <- zonkTcType (idType it_id)
		       ; ifM (isUnitTy it_ty) failM
		       ; return stuff },
943
944
945
946
947
948
949
950

			-- Plan B; a naked bind statment
		    tcGhciStmts [bind_stmt],	

			-- Plan C; check that the let-binding is typeable all by itself.
			-- If not, fail; if so, try to print it.
			-- The two-step process avoids getting two errors: one from
			-- the expression itself, and one from the 'print it' part
951
952
953
954
			-- This two-step story is very clunky, alas
		    do { checkNoErrs (tcGhciStmts [let_stmt]) 
				--- checkNoErrs defeats the error recovery of let-bindings
		       ; tcGhciStmts [let_stmt, print_it] }
955
956
	  ]}

957
958
mkPlan stmt@(L loc (BindStmt {}))
  | [L _ v] <- collectLStmtBinders stmt		-- One binder, for a bind stmt 
959
960
961
962
963
964
965
  = do	{ let print_v  = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar v))
			          	   (HsVar thenIOName) placeHolderType
	-- The plans are:
	--	[stmt; print v]		but not if v::()
	--	[stmt]
	; runPlans [do { stuff@([v_id], _) <- tcGhciStmts [stmt, print_v]
		       ; v_ty <- zonkTcType (idType v_id)
966
		       ; ifM (isUnitTy v_ty || not (isTauTy v_ty)) failM
967
968
969
		       ; return stuff },
		    tcGhciStmts [stmt]
	  ]}
970
971

mkPlan stmt
972
  = tcGhciStmts [stmt]
973

974
---------------------------
975
976
tcGhciStmts :: [LStmt Name] -> TcM PlanResult
tcGhciStmts stmts
977
 = do { ioTyCon <- tcLookupTyCon ioTyConName ;
978
	ret_id  <- tcLookupId returnIOName ;		-- return @ IO
979
	let {
980
	    io_ty     = mkTyConApp ioTyCon [] ;
981
982
	    ret_ty    = mkListTy unitTy ;
	    io_ret_ty = mkTyConApp ioTyCon [ret_ty] ;
983

984
	    names = map unLoc (collectLStmtsBinders stmts) ;
985

986
987
988
989
990
991
992
993
994
995
996
		-- mk_return builds the expression
		--	returnIO @ [()] [coerce () x, ..,  coerce () z]
		--
		-- Despite the inconvenience of building the type applications etc,
		-- this *has* to be done in type-annotated post-typecheck form
		-- because we are going to return a list of *polymorphic* values
		-- coerced to type (). If we built a *source* stmt
		--	return [coerce x, ..., coerce z]
		-- then the type checker would instantiate x..z, and we wouldn't
		-- get their *polymorphic* values.  (And we'd get ambiguity errs
		-- if they were overloaded, since they aren't applied to anything.)
997
998
	    mk_return ids = nlHsApp (noLoc $ TyApp (nlHsVar ret_id) [ret_ty]) 
			 	    (noLoc $ ExplicitList unitTy (map mk_item ids)) ;
999
	    mk_item id = nlHsApp (noLoc $ TyApp (nlHsVar unsafeCoerceId) [idType id, unitTy])
1000
		    	         (nlHsVar id) 
1001
	 } ;
1002

1003
1004
	-- OK, we're ready to typecheck the stmts
	traceTc (text "tcs 2") ;
1005
	((tc_stmts, ids), lie) <- getLIE $ 
1006
				  tcStmts DoExpr (tcDoStmt io_ty) stmts io_ret_ty $ \ _ ->
1007
1008
1009
1010
1011
1012
1013
1014
				  mappM tcLookupId names ;
					-- Look up the names right in the middle,
					-- where they will all be in scope

	-- Simplify the context
	const_binds <- checkNoErrs (tcSimplifyInteractive lie) ;
		-- checkNoErrs ensures that the plan fails if context redn fails

1015
	return (ids, mkHsDictLet const_binds $
1016
1017
		     noLoc (HsDo DoExpr tc_stmts (mk_return ids) io_ret_ty))
    }
1018
\end{code}
1019
1020


1021
tcRnExpr just finds the type of an expression
1022

1023
1024
1025
1026
1027
1028
1029
\begin{code}
tcRnExpr :: HscEnv
	 -> InteractiveContext
	 -> LHsExpr RdrName
	 -> IO (Maybe Type)
tcRnExpr hsc_env ictxt rdr_expr
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
1030
    setInteractiveContext hsc_env ictxt $ do {
1031

1032
1033
    (rn_expr, fvs) <- rnLExpr rdr_expr ;
    failIfErrsM ;
1034

1035
1036
1037
1038
1039
	-- Now typecheck the expression; 
	-- it might have a rank-2 type (e.g. :t runST)
    ((tc_expr, res_ty), lie)	   <- getLIE (tcInferRho rn_expr) ;
    ((qtvs, _, dict_ids), lie_top) <- getLIE (tcSimplifyInfer smpl_doc (tyVarsOfType res_ty) lie)  ;
    tcSimplifyInteractive lie_top ;
1040
    qtvs' <- mappM zonkQuantifiedTyVar qtvs ;
1041

1042
    let { all_expr_ty = mkForAllTys qtvs' $
1043
1044
1045
1046
1047
1048
1049
    		        mkFunTys (map idType dict_ids)	$
    		        res_ty } ;
    zonkTcType all_expr_ty
    }
  where
    smpl_doc = ptext SLIT("main expression")
\end{code}
1050

1051
tcRnType just finds the kind of a type
1052

1053
1054
1055
1056
1057
1058
1059
\begin{code}
tcRnType :: HscEnv
	 -> InteractiveContext
	 -> LHsType RdrName
	 -> IO (Maybe Kind)
tcRnType hsc_env ictxt rdr_type
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
1060
    setInteractiveContext hsc_env ictxt $ do {
1061

1062
1063
    rn_type <- rnLHsType doc rdr_type ;
    failIfErrsM ;
1064

1065
1066
1067
1068
1069
1070
	-- Now kind-check the type
    (ty', kind) <- kcHsType rn_type ;
    return kind
    }
  where
    doc = ptext SLIT("In GHCi input")
1071

1072
#endif /* GHCi */
1073
1074
1075
\end{code}


1076
1077
1078
1079
1080
%************************************************************************
%*									*
	More GHCi stuff, to do with browsing and getting info
%*									*
%************************************************************************
1081
1082
1083

\begin{code}
#ifdef GHCI
1084
1085
1086
1087
1088
-- ASSUMES that the module is either in the HomePackageTable or is
-- a package module with an interface on disk.  If neither of these is
-- true, then the result will be an error indicating the interface
-- could not be found.
getModuleExports :: HscEnv -> Module -> IO (Messages, Maybe NameSet)
1089
getModuleExports hsc_env mod
1090
  = initTc hsc_env HsSrcFile iNTERACTIVE (tcGetModuleExports mod)
1091