TcRnDriver.lhs 43.7 KB
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%
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% (c) The University of Glasgow 2006
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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
import StaticFlags
import HsSyn
import RdrHsSyn

import PrelNames
import RdrName
import TcHsSyn
import TcExpr
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import TcRnMonad
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import TcType
import Inst
import InstEnv
import FamInstEnv
import TcBinds
import TcDefaults
import TcEnv
import TcRules
import TcForeign
import TcInstDcls
import TcIface
import MkIface
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import IfaceSyn
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import TcSimplify
import TcTyClsDecls
import LoadIface
import RnNames
import RnEnv
import RnSource
import RnHsDoc
import PprCore
import CoreSyn
import ErrUtils
import Id
import Var
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import Module
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import UniqFM
import Name
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import NameSet
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import NameEnv
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import TyCon
import SrcLoc
import HscTypes
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import Outputable

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#ifdef GHCI
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import TcHsType
import TcMType
import TcMatches
import TcGadt
import RnTypes
import RnExpr
import IfaceEnv
import MkId
import TysWiredIn
import IdInfo
import {- Kind parts of -} Type
import BasicTypes
import Data.Maybe
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#endif

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import FastString
import Util
import Bag
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import Control.Monad    ( unless )
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import Data.Maybe	( isJust )
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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 
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			  import_decls local_decls mod_deprec _ module_info maybe_doc))
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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;
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	(rn_imports, rdr_env, imports) <- rnImports import_decls ;
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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
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        traceIf (text "rdr_env: " <+> ppr rdr_env) ;
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	failIfErrsM ;

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		-- Load any orphan-module and family instance-module
		-- interfaces, so that their rules and instance decls will be
		-- found.
	loadOrphanModules (imp_orphs  imports) False ;
	loadOrphanModules (imp_finsts imports) True  ;
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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, exports) <- rnExports (isJust maybe_mod) export_ies ;
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		-- Rename the Haddock documentation header 
	rn_module_doc <- rnMbHsDoc maybe_doc ;

		-- Rename the Haddock module info 
	rn_description <- rnMbHsDoc (hmi_description module_info) ;
	let { rn_module_info = module_info { hmi_description = rn_description } } ;

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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 (availsToNameSet exports),
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				     tcg_deprecs = tcg_deprecs tcg_env `plusDeprecs` 
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						   mod_deprecs,
				     tcg_doc = rn_module_doc, 
				     tcg_hmi = rn_module_info
				  }
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		-- 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 ;
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	my_exports = map (Avail . idName) bndrs ;
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		-- 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,
				mg_boot	     = False,
				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_fam_insts = tcg_fam_insts tcg_env,
				mg_rules     = [],
				mg_binds     = core_binds,
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				-- Stubs
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				mg_rdr_env   = emptyGlobalRdrEnv,
				mg_fix_env   = emptyFixityEnv,
				mg_deprecs   = NoDeprecs,
				mg_foreign   = NoStubs
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		    } } ;
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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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	(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
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	rnDump (ppr rn_splice_expr) ;
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	-- 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")
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	; (tcg_env, inst_infos, _binds) 
            <- tcInstDecls1 tycl_decls (hs_instds rn_group) (hs_derivds rn_group)
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	; 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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--
-- The bindings we return give bindings for the dfuns defined in the
-- hs-boot file, such as 	$fbEqT = $fEqT

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checkHiBootIface
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	(TcGblEnv { tcg_insts = local_insts, tcg_fam_insts = local_fam_insts,
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		    tcg_type_env = local_type_env })
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	(ModDetails { md_insts = boot_insts, md_fam_insts = boot_fam_insts,
		      md_types = boot_type_env })
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  = do	{ traceTc (text "checkHiBootIface" <+> (ppr boot_type_env $$ ppr boot_insts)) ;
	; mapM_ check_one (typeEnvElts boot_type_env)
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	; dfun_binds <- mapM check_inst boot_insts
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	; unless (null boot_fam_insts) $
	    panic ("TcRnDriver.checkHiBootIface: Cannot handle family " ++
		   "instances in boot files yet...")
            -- FIXME: Why?  The actual comparison is not hard, but what would
            --	      be the equivalent to the dfun bindings returned for class
            --	      instances?  We can't easily equate tycons...
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	; return (unionManyBags dfun_binds) }
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  where
    check_one boot_thing
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      | isImplicitTyThing boot_thing = return ()
      | name `elem` dfun_names       = return ()	
      | isWiredInName name	     = return ()	-- No checking for wired-in names.  In particular,
							-- 'error' is handled by a rather gross hack
							-- (see comments in GHC.Err.hs-boot)
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      | Just real_thing <- lookupTypeEnv local_type_env name
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      = do { let boot_decl = tyThingToIfaceDecl boot_thing
	         real_decl = tyThingToIfaceDecl real_thing
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	   ; 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)
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      where
	name = getName boot_thing

    dfun_names = map getName boot_insts

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    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 }
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	    (dfun:_) -> return (unitBag $ noLoc $ VarBind local_boot_dfun (nlHsVar dfun))
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	where
	  boot_dfun = instanceDFunId boot_inst
	  boot_inst_ty = idType boot_dfun
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	  local_boot_dfun = Id.mkExportedLocalId (idName boot_dfun) boot_inst_ty
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----------------
missingBootThing thing
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  = ppr thing <+> ptext SLIT("is defined in the hs-boot file, but not in the module")
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bootMisMatch thing boot_decl real_decl
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  = vcat [ppr thing <+> ptext SLIT("has conflicting definitions in the module and its hs-boot file"),
	  ptext SLIT("Decl") <+> ppr real_decl,
	  ptext SLIT("Boot file:") <+> ppr boot_decl]
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instMisMatch inst
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  = hang (ppr inst)
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       2 (ptext SLIT("is defined in the hs-boot file, but not in the module"))
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\end{code}

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%************************************************************************
%*									*
	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.
559
560

\begin{code}
561
tcRnGroup :: ModDetails -> HsGroup RdrName -> TcM (TcGblEnv, TcLclEnv)
562
	-- Returns the variables free in the decls, for unused-binding reporting
563
tcRnGroup boot_details decls
564
565
566
 = do {		-- Rename the declarations
	(tcg_env, rn_decls) <- rnTopSrcDecls decls ;
	setGblEnv tcg_env $ do {
567

568
		-- Typecheck the declarations
569
	tcTopSrcDecls boot_details rn_decls 
570
  }}
571

572
573
574
575
------------------------------------------------
rnTopSrcDecls :: HsGroup RdrName -> TcM (TcGblEnv, HsGroup Name)
rnTopSrcDecls group
 = do { 	-- Bring top level binders into scope
576
577
	tcg_env <- importsFromLocalDecls group ;
	setGblEnv tcg_env $ do {
578

579
	failIfErrsM ;	-- No point in continuing if (say) we have duplicate declarations
580

581
582
583
		-- Rename the source decls
	(tcg_env, rn_decls) <- rnSrcDecls group ;
	failIfErrsM ;
584

585
586
587
588
589
590
591
		-- 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 };

592
593
		-- Dump trace of renaming part
	rnDump (ppr rn_decls) ;
594

595
	return (tcg_env', rn_decls)
596
   }}
597

598
------------------------------------------------
599
600
tcTopSrcDecls :: ModDetails -> HsGroup Name -> TcM (TcGblEnv, TcLclEnv)
tcTopSrcDecls boot_details
601
602
	(HsGroup { hs_tyclds = tycl_decls, 
		   hs_instds = inst_decls,
603
                   hs_derivds = deriv_decls,
604
605
606
607
608
609
610
		   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") ;
611

612
	tcg_env <- checkNoErrs (tcTyAndClassDecls boot_details tycl_decls) ;
613
614
615
616
617
	-- 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) ;
618
619


620
621
622
623
	setGblEnv tcg_env	$ do {
		-- Source-language instances, including derivings,
		-- and import the supporting declarations
        traceTc (text "Tc3") ;
624
625
	(tcg_env, inst_infos, deriv_binds) 
            <- tcInstDecls1 tycl_decls inst_decls deriv_decls;
626
	setGblEnv tcg_env	$ do {
627

628
629
630
631
632
	        -- 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 {
633

634
635
636
637
		-- Default declarations
        traceTc (text "Tc4a") ;
	default_tys <- tcDefaults default_decls ;
	updGblEnv (\gbl -> gbl { tcg_default = default_tys }) $ do {
638
	
639
640
641
642
		-- Value declarations next
		-- We also typecheck any extra binds that came out 
		-- of the "deriving" process (deriv_binds)
        traceTc (text "Tc5") ;
643
	(tc_val_binds, tcl_env) <- tcTopBinds (val_binds `plusHsValBinds` deriv_binds) ;
644
	setLclTypeEnv tcl_env 	$ do {
645

646
647
	     	-- Second pass over class and instance declarations, 
        traceTc (text "Tc6") ;
648
	(inst_binds, tcl_env) <- tcInstDecls2 tycl_decls inst_infos ;
649
	showLIE (text "after instDecls2") ;
650

651
652
653
654
		-- Foreign exports
		-- They need to be zonked, so we return them
        traceTc (text "Tc7") ;
	(foe_binds, foe_decls) <- tcForeignExports foreign_decls ;
655

656
657
		-- Rules
	rules <- tcRules rule_decls ;
658

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661
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664
665
666
667
668
669
670
		-- 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 } } ;
671
  	return (tcg_env', tcl_env)
672
    }}}}}}
673
674
\end{code}

675

676
677
%************************************************************************
%*									*
678
	Checking for 'main'
679
680
681
682
%*									*
%************************************************************************

\begin{code}
683
684
checkMain :: TcM TcGblEnv
-- If we are in module Main, check that 'main' is defined.
685
checkMain 
686
  = do { ghc_mode <- getGhcMode ;
687
	 tcg_env   <- getGblEnv ;
688
	 dflags    <- getDOpts ;
689
	 let { main_mod = mainModIs dflags ;
690
	       main_fn  = case mainFunIs dflags of {
691
				Just fn -> mkRdrUnqual (mkVarOccFS (mkFastString fn)) ;
692
693
				Nothing -> main_RDR_Unqual } } ;
	
694
	 check_main ghc_mode tcg_env main_mod main_fn
695
    }
696

697

698
check_main ghc_mode tcg_env main_mod main_fn
699
 | mod /= main_mod
700
701
 = traceTc (text "checkMain not" <+> ppr main_mod <+> ppr mod) >>
   return tcg_env
702

703
704
705
706
707
708
 | 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 {
709
710
	     Nothing -> do { traceTc (text "checkMain fail" <+> ppr main_mod <+> ppr main_fn)
			   ; complain_no_main	
711
712
			   ; return tcg_env } ;
	     Just main_name -> do
713
714
	{ traceTc (text "checkMain found" <+> ppr main_mod <+> ppr main_fn)
	; let { rhs = nlHsApp (nlHsVar runMainIOName) (nlHsVar main_name) }
715
		   	-- :Main.main :: IO () = runMainIO main 
716

717
	; (main_expr, ty) <- setSrcSpan (srcLocSpan (getSrcLoc main_name)) $
718
			     tcInferRho rhs
719

720
721
722
723
724
725
726
727
728
729
730
731
732
	-- 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 
733
				   (mkVarOccFS FSLIT("main")) 
734
				   (getSrcLoc main_name)
735
	      ; root_main_id = Id.mkExportedLocalId root_main_name ty
736
	      ; main_bind    = noLoc (VarBind root_main_id main_expr) }
737

738
739
740
741
	; return (tcg_env { tcg_binds = tcg_binds tcg_env 
					`snocBag` main_bind,
			    tcg_dus   = tcg_dus tcg_env
				        `plusDU` usesOnly (unitFV main_name)
742
743
			-- Record the use of 'main', so that we don't 
			-- complain about it being defined but not used
744
745
746
		 }) 
    }}}
  where
747
    mod = tcg_mod tcg_env
748
 
749
    complain_no_main | ghc_mode == Interactive = return ()
750
751
752
753
		     | 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.
754

755
756
757
758
    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}
759

760
761
762
763
764
%*********************************************************
%*						 	 *
		GHCi stuff
%*							 *
%*********************************************************
765

766
767
\begin{code}
#ifdef GHCI
768
769
770
setInteractiveContext :: HscEnv -> InteractiveContext -> TcRn a -> TcRn a
setInteractiveContext hsc_env icxt thing_inside 
  = let 
771
772
773
774
	-- 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)
775
776
777
778
779
780
781
782
783
784
    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 }
785
\end{code}
786

787

788
789
790
791
792
793
794
795
796
797
\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 ().
798

799
800
tcRnStmt hsc_env ictxt rdr_stmt
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
801
    setInteractiveContext hsc_env ictxt $ do {
802

803
    -- Rename; use CmdLineMode because tcRnStmt is only used interactively
804
    (([rn_stmt], _), fvs) <- rnStmts DoExpr [rdr_stmt] (return ((), emptyFVs)) ;
805
806
807
808
    traceRn (text "tcRnStmt" <+> vcat [ppr rdr_stmt, ppr rn_stmt, ppr fvs]) ;
    failIfErrsM ;
    
    -- The real work is done here
809
810
811
    (bound_ids, tc_expr) <- mkPlan rn_stmt ;
    zonked_expr <- zonkTopLExpr tc_expr ;
    zonked_ids  <- zonkTopBndrs bound_ids ;
812
    
813
814
815
816
	-- 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) ;

817
    traceTc (text "tcs 1") ;
818
819
820
821
822
823
824
825
826
    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
827
	global_ids = map globaliseAndTidy zonked_ids ;
828
829
830
831
    
		-- Update the interactive context
	rn_env   = ic_rn_local_env ictxt ;
	type_env = ic_type_env ictxt ;
832

833
834
	bound_names = map idName global_ids ;
	new_rn_env  = extendLocalRdrEnv rn_env bound_names ;
835

836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
{- ---------------------------------------------
   At one stage I removed any shadowed bindings from the type_env;
   they are inaccessible but might, I suppose, cause a space leak if we leave them there.
   However, with Template Haskell they aren't necessarily inaccessible.  Consider this
   GHCi session
	 Prelude> let f n = n * 2 :: Int
	 Prelude> fName <- runQ [| f |]
	 Prelude> $(return $ AppE fName (LitE (IntegerL 7)))
	 14
	 Prelude> let f n = n * 3 :: Int
	 Prelude> $(return $ AppE fName (LitE (IntegerL 7)))
   In the last line we use 'fName', which resolves to the *first* 'f'
   in scope. If we delete it from the type env, GHCi crashes because
   it doesn't expect that.
 
   Hence this code is commented out

853
854
855
856
	shadowed = [ n | name <- bound_names,
			 let rdr_name = mkRdrUnqual (nameOccName name),
			 Just n <- [lookupLocalRdrEnv rn_env rdr_name] ] ;
	filtered_type_env = delListFromNameEnv type_env shadowed ;
857
-------------------------------------------------- -}
858

859
	new_type_env = extendTypeEnvWithIds type_env global_ids ;
860
861
862
	new_ic = ictxt { ic_rn_local_env = new_rn_env, 
		  	 ic_type_env     = new_type_env }
    } ;
863

864
865
    dumpOptTcRn Opt_D_dump_tc 
    	(vcat [text "Bound Ids" <+> pprWithCommas ppr global_ids,
866
    	       text "Typechecked expr" <+> ppr zonked_expr]) ;
867

868
    returnM (new_ic, bound_names, zonked_expr)
869
    }
870
871
872
  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))])
873

874
875
876
globaliseAndTidy :: Id -> Id
globaliseAndTidy id
-- Give the Id a Global Name, and tidy its type
877
  = Id.setIdType (globaliseId VanillaGlobal id) tidy_type
878
879
880
  where
    tidy_type = tidyTopType (idType id)
\end{code}
881

882
Here is the grand plan, implemented in tcUserStmt
883

884
885
886
887
	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,...]
888

889
890
	pat <- expr		==> 	expr >>= \ pat -> return [coerce HVal x, coerce HVal y, ...]
					bindings: [x,y,...]
891

892
893
894
895
896
	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]
897

898
899
	expr (of non-IO type, 
	  result not showable)	==>	error
900

901

902
903
\begin{code}
---------------------------
904
905
906
907
908
909
910
911
912
913
914
915
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
916
917
mkPlan (L loc (ExprStmt expr _ _))	-- An expression typed at the prompt 
  = do	{ uniq <- newUnique		-- is treated very specially
918
	; let fresh_it  = itName uniq
919
920
	      the_bind  = L loc $ mkFunBind (L loc fresh_it) matches
	      matches   = [mkMatch [] expr emptyLocalBinds]
921
	      let_stmt  = L loc $ LetStmt (HsValBinds (ValBindsOut [(NonRecursive,unitBag the_bind)] []))
922
923
924
925
926
927
928
929
930
	      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]	
931
932
	; runPlans [	-- Plan A
		    do { stuff@([it_id], _) <- tcGhciStmts [bind_stmt, print_it]
933
934
935
		       ; it_ty <- zonkTcType (idType it_id)
		       ; ifM (isUnitTy it_ty) failM
		       ; return stuff },
936
937
938
939
940
941
942
943

			-- 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
944
945
946
947
			-- 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] }
948
949
	  ]}

950
951
mkPlan stmt@(L loc (BindStmt {}))
  | [L _ v] <- collectLStmtBinders stmt		-- One binder, for a bind stmt 
952
953
  = do	{ let print_v  = L loc $ ExprStmt (nlHsApp (nlHsVar printName) (nlHsVar v))
			          	   (HsVar thenIOName) placeHolderType
954
955
956
957
958
959
960
961

	; print_bind_result <- doptM Opt_PrintBindResult
	; let print_plan = do
		  { stuff@([v_id], _) <- tcGhciStmts [stmt, print_v]
		  ; v_ty <- zonkTcType (idType v_id)
		  ; ifM (isUnitTy v_ty || not (isTauTy v_ty)) failM
		  ; return stuff }

962
963
964
	-- The plans are:
	--	[stmt; print v]		but not if v::()
	--	[stmt]
965
966
967
	; runPlans ((if print_bind_result then [print_plan] else []) ++
		    [tcGhciStmts [stmt]])
	}
968
969

mkPlan stmt
970
  = tcGhciStmts [stmt]
971

972
---------------------------
973
974
tcGhciStmts :: [LStmt Name] -> TcM PlanResult
tcGhciStmts stmts
975
 = do { ioTyCon <- tcLookupTyCon ioTyConName ;
976
	ret_id  <- tcLookupId returnIOName ;		-- return @ IO
977
	let {
978
	    io_ty     = mkTyConApp ioTyCon [] ;
979
980
	    ret_ty    = mkListTy unitTy ;
	    io_ret_ty = mkTyConApp ioTyCon [ret_ty] ;
981
982
	    tc_io_stmts stmts = tcStmts DoExpr (tcDoStmt io_ty) stmts 
				        (emptyRefinement, io_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
	    mk_return ids = nlHsApp (nlHsTyApp ret_id [ret_ty]) 
998
			 	    (noLoc $ ExplicitList unitTy (map mk_item ids)) ;
999
1000
	    mk_item id = nlHsApp (nlHsTyApp unsafeCoerceId [idType id, unitTy])
		    	         (nlHsVar id) 
1001
	 } ;
1002

1003
1004
	-- OK, we're ready to typecheck the stmts
	traceTc (text "tcs 2") ;
1005
1006
	((tc_stmts, ids), lie) <- getLIE $ tc_io_stmts stmts $ \ _ ->
					   mappM tcLookupId names ;
1007
1008
1009
1010
1011
1012
1013
					-- 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

1014
	return (ids, mkHsDictLet const_binds $
1015
1016
		     noLoc (HsDo DoExpr tc_stmts (mk_return ids) io_ret_ty))
    }
1017
\end{code}
1018
1019


1020
tcRnExpr just finds the type of an expression
1021

1022
1023
1024
1025
1026
1027
1028
\begin{code}
tcRnExpr :: HscEnv
	 -> InteractiveContext
	 -> LHsExpr RdrName
	 -> IO (Maybe Type)
tcRnExpr hsc_env ictxt rdr_expr
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
1029
    setInteractiveContext hsc_env ictxt $ do {
1030

1031
1032
    (rn_expr, fvs) <- rnLExpr rdr_expr ;
    failIfErrsM ;
1033

1034
1035
1036
1037
1038
	-- 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 ;
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    qtvs' <- mappM zonkQuantifiedTyVar qtvs ;
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    let { all_expr_ty = mkForAllTys qtvs' $
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    		        mkFunTys (map idType dict_ids)	$
    		        res_ty } ;
    zonkTcType all_expr_ty
    }
  where
    smpl_doc = ptext SLIT("main expression")
\end{code}
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tcRnType just finds the kind of a type
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\begin{code}
tcRnType :: HscEnv
	 -> InteractiveContext
	 -> LHsType RdrName
	 -> IO (Maybe Kind)
tcRnType hsc_env ictxt rdr_type
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
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    setInteractiveContext hsc_env ictxt $ do {
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    rn_type <- rnLHsType doc rdr_type ;
    failIfErrsM ;
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	-- Now kind-check the type
    (ty', kind) <- kcHsType rn_type ;
    return kind
    }
  where
    doc = ptext SLIT("In GHCi input")
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#endif /* GHCi */
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\end{code}


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%************************************************************************
%*									*
	More GHCi stuff, to do with browsing and getting info
%*									*
%************************************************************************
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\begin{code}
#ifdef GHCI
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-- 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.
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getModuleExports :: HscEnv -> Module -> IO (Messages, Maybe [AvailInfo])
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getModuleExports hsc_env mod
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  = initTc hsc_env HsSrcFile iNTERACTIVE (tcGetModuleExports mod)
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tcGetModuleExports :: Module -> TcM [AvailInfo]
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tcGetModuleExports mod = do
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Simon Marlow committed
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  let doc = ptext SLIT("context for compiling statements")
  iface <- initIfaceTcRn $ loadSysInterface doc mod
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  loadOrphanModules (dep_orphs (mi_deps iface)) False 
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  		-- Load any orphan-module interfaces,
  		-- so their instances are visible
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  loadOrphanModules (dep_finsts (mi_deps iface)) True
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  		-- Load any family instance-module interfaces,
  		-- so all family instances are visible
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  ifaceExportNames (mi_exports iface)
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tcRnLookupRdrName :: HscEnv -> RdrName -> IO (Maybe [Name])
tcRnLookupRdrName hsc_env rdr_name 
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  = initTcPrintErrors hsc_env iNTERACTIVE $ 
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    setInteractiveContext hsc_env (hsc_IC hsc_env) $ 
    lookup_rdr_name rdr_name
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lookup_rdr_name rdr_name = do {
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	-- If the identifier is a constructor (begins with an
	-- upper-case letter), then we need to consider both
	-- constructor and type class identifiers.
    let { rdr_names = dataTcOccs rdr_name } ;
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	-- results :: [Either Messages Name]
    results <- mapM (tryTcErrs . lookupOccRn) rdr_names ;
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    traceRn (text "xx" <+> vcat [ppr rdr_names, ppr (map snd results)]);
	-- The successful lookups will be (Just name)
    let { (warns_s, good_names) = unzip [ (msgs, name) 
					| (msgs, Just name) <- results] ;
	  errs_s = [msgs | (msgs, Nothing) <- results] } ;
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	-- Fail if nothing good happened, else add warnings
    if null good_names then
		-- No lookup succeeded, so
		-- pick the first error message and report it
		-- ToDo: If one of the errors is "could be Foo.X or Baz.X",
		--	 while the other is "X is not in scope", 
		--	 we definitely want the former; but we might pick the latter
	do { addMessages (head errs_s) ; failM }
      else 			-- Add deprecation warnings
	mapM_ addMessages warns_s ;
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    return good_names
 }


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tcRnLookupName :: HscEnv -> Name -> IO (Maybe TyThing)
tcRnLookupName hsc_env name
  = initTcPrintErrors hsc_env iNTERACTIVE $ 
    setInteractiveContext hsc_env (hsc_IC hsc_env) $
    tcLookupGlobal name


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tcRnGetInfo :: HscEnv
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	    -> Name
	    -> IO (Maybe (TyThing, Fixity, [Instance]))
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-- Used to implemnent :info in GHCi
--
-- Look up a RdrName and return all the TyThings it might be
-- A capitalised RdrName is given to us in the DataName namespace,
-- but we want to treat it as *both* a data constructor 
--  *and* as a type or class constructor; 
-- hence the call to dataTcOccs, and we return up to two results
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tcRnGetInfo hsc_env name
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  = initTcPrintErrors hsc_env iNTERACTIVE $ 
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    let ictxt = hsc_IC hsc_env in
    setInteractiveContext hsc_env ictxt $ do