[project @ 2000-11-07 13:12:21 by simonpj]

More small changes

31 files changed, 135 insertions, 159 deletions

diff --git a/ghc/compiler/basicTypes/OccName.lhs b/ghc/compiler/basicTypes/OccName.lhs
index 6a1de9652c..ea370e26fd 100644
--- a/ghc/compiler/basicTypes/OccName.lhs
+++ b/ghc/compiler/basicTypes/OccName.lhs
@@ -40,7 +40,7 @@ module OccName (
 
 #include "HsVersions.h"
 
-import Char	( isDigit, isAlpha, isUpper, isLower, ISALPHANUM, ord, chr, digitToInt )
+import Char	( isDigit, isUpper, isLower, ISALPHANUM, ord, chr, digitToInt )
 import Util	( thenCmp )
 import FiniteMap ( FiniteMap, emptyFM, lookupFM, addToFM, elemFM )
 import Outputable
diff --git a/ghc/compiler/basicTypes/PprEnv.lhs b/ghc/compiler/basicTypes/PprEnv.lhs
index a2df826fa7..36293f3688 100644
--- a/ghc/compiler/basicTypes/PprEnv.lhs
+++ b/ghc/compiler/basicTypes/PprEnv.lhs
@@ -16,8 +16,6 @@ module PprEnv (
 
 #include "HsVersions.h"
 
-import {-# SOURCE #-} DataCon ( DataCon )
-
 import Var		( Id, TyVar )
 import CostCentre	( CostCentre )
 import Type  		( Type )
diff --git a/ghc/compiler/codeGen/CgCase.lhs b/ghc/compiler/codeGen/CgCase.lhs
index 481ef02855..2bca305bdd 100644
--- a/ghc/compiler/codeGen/CgCase.lhs
+++ b/ghc/compiler/codeGen/CgCase.lhs
@@ -1,7 +1,7 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgCase.lhs,v 1.46 2000/09/06 12:21:15 simonmar Exp $
+% $Id: CgCase.lhs,v 1.47 2000/11/07 13:12:22 simonpj Exp $
 %
 %********************************************************
 %*							*
@@ -33,7 +33,7 @@ import CgBindery	( getVolatileRegs, getArgAmodes,
 			  buildContLivenessMask, nukeDeadBindings,
 			)
 import CgCon		( bindConArgs, bindUnboxedTupleComponents )
-import CgHeapery	( altHeapCheck, yield )
+import CgHeapery	( altHeapCheck )
 import CgRetConv	( dataReturnConvPrim, ctrlReturnConvAlg,
 			  CtrlReturnConvention(..)
 			)
@@ -41,13 +41,12 @@ import CgStackery	( allocPrimStack, allocStackTop,
 			  deAllocStackTop, freeStackSlots, dataStackSlots
 			)
 import CgTailCall	( tailCallFun )
-import CgUsages		( getSpRelOffset, getRealSp )
-import CLabel		( CLabel, mkVecTblLabel, mkReturnPtLabel, 
-			  mkDefaultLabel, mkAltLabel, mkReturnInfoLabel,
-			  mkErrorStdEntryLabel, mkClosureTblLabel
+import CgUsages		( getSpRelOffset )
+import CLabel		( mkVecTblLabel, mkClosureTblLabel,
+			  mkDefaultLabel, mkAltLabel, mkReturnInfoLabel
 			)
 import ClosureInfo	( mkLFArgument )
-import CmdLineOpts	( opt_SccProfilingOn, opt_GranMacros )
+import CmdLineOpts	( opt_SccProfilingOn )
 import Id		( Id, idPrimRep, isDeadBinder )
 import DataCon		( DataCon, dataConTag, fIRST_TAG, ConTag,
 			  isUnboxedTupleCon )
@@ -57,7 +56,7 @@ import PrimOp		( primOpOutOfLine, PrimOp(..) )
 import PrimRep		( getPrimRepSize, retPrimRepSize, PrimRep(..)
 			)
 import TyCon		( TyCon, isEnumerationTyCon, isUnboxedTupleTyCon,
-			  isNewTyCon, isAlgTyCon, isFunTyCon, isPrimTyCon,
+			  isFunTyCon, isPrimTyCon,
 			)
 import Type		( Type, typePrimRep, splitAlgTyConApp, 
 			  splitTyConApp_maybe, repType )
diff --git a/ghc/compiler/codeGen/CgExpr.lhs b/ghc/compiler/codeGen/CgExpr.lhs
index 37ef6e8817..90509f3646 100644
--- a/ghc/compiler/codeGen/CgExpr.lhs
+++ b/ghc/compiler/codeGen/CgExpr.lhs
@@ -1,7 +1,7 @@
 %
 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
 %
-% $Id: CgExpr.lhs,v 1.36 2000/10/03 08:43:00 simonpj Exp $
+% $Id: CgExpr.lhs,v 1.37 2000/11/07 13:12:22 simonpj Exp $
 %
 %********************************************************
 %*							*
@@ -39,11 +39,9 @@ import ClosureInfo	( mkClosureLFInfo, mkSelectorLFInfo,
 import CostCentre	( sccAbleCostCentre, isSccCountCostCentre )
 import Id		( idPrimRep, idType, Id )
 import VarSet
-import DataCon		( DataCon, dataConTyCon )
-import PrimOp		( primOpOutOfLine, ccallMayGC,
-			  getPrimOpResultInfo, PrimOp(..), PrimOpResultInfo(..)
-			)
-import PrimRep		( getPrimRepSize, PrimRep(..), isFollowableRep )
+import DataCon		( dataConTyCon )
+import PrimOp		( primOpOutOfLine, getPrimOpResultInfo, PrimOp(..), PrimOpResultInfo(..) )
+import PrimRep		( PrimRep(..), isFollowableRep )
 import TyCon		( maybeTyConSingleCon,
 			  isUnboxedTupleTyCon, isEnumerationTyCon )
 import Type		( Type, typePrimRep, splitTyConApp_maybe, repType )
diff --git a/ghc/compiler/codeGen/SMRep.lhs b/ghc/compiler/codeGen/SMRep.lhs
index c338cf8b3f..d2bb4f7ae2 100644
--- a/ghc/compiler/codeGen/SMRep.lhs
+++ b/ghc/compiler/codeGen/SMRep.lhs
@@ -56,7 +56,6 @@ import Constants	( sTD_HDR_SIZE, pROF_HDR_SIZE,
 			  sTD_ITBL_SIZE, pROF_ITBL_SIZE,
 			  gRAN_ITBL_SIZE, tICKY_ITBL_SIZE )
 import Outputable
-import GlaExts		( Int(..), Int#, (<#), (==#), (<#), (>#) )
 \end{code}
 
 %************************************************************************
diff --git a/ghc/compiler/hsSyn/HsDecls.lhs b/ghc/compiler/hsSyn/HsDecls.lhs
index 54f993da7f..25921364bb 100644
--- a/ghc/compiler/hsSyn/HsDecls.lhs
+++ b/ghc/compiler/hsSyn/HsDecls.lhs
@@ -16,7 +16,7 @@ module HsDecls (
 	DeprecDecl(..), DeprecTxt,
 	hsDeclName, instDeclName, tyClDeclName, tyClDeclNames,
 	isClassDecl, isSynDecl, isDataDecl, isIfaceSigDecl, countTyClDecls,
-	mkClassDeclSysNames, isIfaceRuleDecl,
+	mkClassDeclSysNames, isIfaceRuleDecl, ifaceRuleDeclName,
 	getClassDeclSysNames
     ) where
 
@@ -36,7 +36,7 @@ import CallConv		( CallConv, pprCallConv )
 
 -- others:
 import FunDeps		( pprFundeps )
-import Class		( FunDep )
+import Class		( FunDep, DefMeth(..) )
 import CStrings		( CLabelString, pprCLabelString )
 import Outputable	
 import SrcLoc		( SrcLoc )
@@ -296,13 +296,17 @@ eq_hsFD env (ns1,ms1) (ns2,ms2)
 eq_cls_sig env (ClassOpSig n1 dm1 ty1 _) (ClassOpSig n2 dm2 ty2 _)
   = n1==n2 && dm1 `eq_dm` dm2 && eq_hsType env ty1 ty2
   where
-	-- Ignore the name of the default method.
+	-- Ignore the name of the default method for (DefMeth id)
 	-- This is used for comparing declarations before putting
 	-- them into interface files, and the name of the default 
 	-- method isn't relevant
-    (Just (explicit_dm1)) `eq_dm` (Just (explicit_dm2)) = explicit_dm1 == explicit_dm2
-    Nothing		    `eq_dm` Nothing		    = True
-    dm1			    `eq_dm` dm2			    = False
+    Nothing	       `eq_dm` Nothing		  = True
+    (Just NoDefMeth)   `eq_dm` (Just NoDefMeth)   = True
+    (Just GenDefMeth)  `eq_dm` (Just GenDefMeth)  = True
+    (Just (DefMeth _)) `eq_dm` (Just (DefMeth _)) = True
+    dm1		       `eq_dm` dm2		  = False
+
+    
 \end{code}
 
 \begin{code}
@@ -424,7 +428,7 @@ conDeclsNames cons
 eq_ConDecl env (ConDecl n1 _ tvs1 cxt1 cds1 _)
 	       (ConDecl n2 _ tvs2 cxt2 cds2 _)
   = n1 == n2 &&
-    (eqWithHsTyVars tvs1 tvs2	$ \ env ->
+    (eq_hsTyVars env tvs1 tvs2	$ \ env ->
      eq_hsContext env cxt1 cxt2	&&
      eq_ConDetails env cds1 cds2)
 
@@ -642,6 +646,11 @@ data RuleDecl name pat
 isIfaceRuleDecl (HsRule _ _ _ _ _ _) = False
 isIfaceRuleDecl other		     = True
 
+ifaceRuleDeclName :: RuleDecl name pat -> name
+ifaceRuleDeclName (IfaceRule _ _ n _ _ _) = n
+ifaceRuleDeclName (IfaceRuleOut n r)	  = n
+ifaceRuleDeclName (HsRule fs _ _ _ _ _)   = pprPanic "ifaceRuleDeclName" (ppr fs)
+
 data RuleBndr name
   = RuleBndr name
   | RuleBndrSig name (HsType name)
diff --git a/ghc/compiler/hsSyn/HsTypes.lhs b/ghc/compiler/hsSyn/HsTypes.lhs
index 956b02f3dc..bd5178112f 100644
--- a/ghc/compiler/hsSyn/HsTypes.lhs
+++ b/ghc/compiler/hsSyn/HsTypes.lhs
@@ -17,7 +17,7 @@ module HsTypes (
 
 	-- Equality over Hs things
 	, EqHsEnv, emptyEqHsEnv, extendEqHsEnv,
-	, eqWithHsTyVars, eq_hsVar, eq_hsVars, eq_hsType, eq_hsContext, eqListBy
+	, eqWithHsTyVars, eq_hsVar, eq_hsVars, eq_hsTyVars, eq_hsType, eq_hsContext, eqListBy
 
 	-- Converting from Type to HsType
 	, toHsType, toHsTyVar, toHsTyVars, toHsContext, toHsFDs
diff --git a/ghc/compiler/javaGen/PrintJava.lhs b/ghc/compiler/javaGen/PrintJava.lhs
index edaf8e594f..eb2811d38f 100644
--- a/ghc/compiler/javaGen/PrintJava.lhs
+++ b/ghc/compiler/javaGen/PrintJava.lhs
@@ -81,11 +81,6 @@ clazz = \mfs -> \n -> \x -> \is -> \ms ->
   $$ indent ms 
   $$ text "}"
 
-staticblock = \ss ->
-  text "static" <+> text "{"
-  $$ indent ss
-  $$ text "}"
-    
 modifiers mfs = hsep (map modifier mfs)
     
 modifier mf = text $ map toLower (show mf)
diff --git a/ghc/compiler/main/CmdLineOpts.lhs b/ghc/compiler/main/CmdLineOpts.lhs
index 747ad0455a..69b856595b 100644
--- a/ghc/compiler/main/CmdLineOpts.lhs
+++ b/ghc/compiler/main/CmdLineOpts.lhs
@@ -341,10 +341,6 @@ lookup_def_int sw def = case (lookup_str sw) of
 			    Nothing -> def		-- Use default
 		  	    Just xx -> read xx
 
-lookup_def_char sw def = case (lookup_str sw) of
-		  	    Just (xx:_) -> xx
-			    _           -> def		-- Use default
-
 lookup_def_float sw def = case (lookup_str sw) of
 			    Nothing -> def		-- Use default
 		  	    Just xx -> read xx
@@ -604,11 +600,6 @@ isAmongSimpl on_switches		-- Switches mentioned later occur *earlier*
 			    || sw `is_elem` ss
 \end{code}
 
-Default settings for simplifier switches
-
-\begin{code}
-defaultSimplSwitches = [MaxSimplifierIterations	1]
-\end{code}
 
 %************************************************************************
 %*									*
diff --git a/ghc/compiler/main/CodeOutput.lhs b/ghc/compiler/main/CodeOutput.lhs
index 91ff5ed465..63a090e82c 100644
--- a/ghc/compiler/main/CodeOutput.lhs
+++ b/ghc/compiler/main/CodeOutput.lhs
@@ -31,7 +31,6 @@ import ErrUtils		( dumpIfSet_dyn )
 import Outputable
 import CmdLineOpts	( DynFlags, HscLang(..), dopt_OutName )
 import TmpFiles		( newTempName )
-import UniqSupply	( mkSplitUniqSupply )
 
 import IO		( IOMode(..), hClose, openFile, Handle )
 \end{code}
diff --git a/ghc/compiler/main/HscTypes.lhs b/ghc/compiler/main/HscTypes.lhs
index d29b7f4770..498add4732 100644
--- a/ghc/compiler/main/HscTypes.lhs
+++ b/ghc/compiler/main/HscTypes.lhs
@@ -13,7 +13,7 @@ module HscTypes (
 	lookupIface, lookupIfaceByModName,
 	emptyModIface,
 
-	IfaceDecls(..), 
+	IfaceDecls, mkIfaceDecls, dcl_tycl, dcl_rules, dcl_insts,
 
 	VersionInfo(..), initialVersionInfo,
 
@@ -60,7 +60,7 @@ import TyCon		( TyCon )
 
 import BasicTypes	( Version, initialVersion, Fixity )
 
-import HsSyn		( DeprecTxt )
+import HsSyn		( DeprecTxt, tyClDeclName, ifaceRuleDeclName )
 import RdrHsSyn		( RdrNameInstDecl, RdrNameRuleDecl, RdrNameTyClDecl )
 import RnHsSyn		( RenamedTyClDecl, RenamedRuleDecl, RenamedInstDecl )
 
@@ -71,7 +71,7 @@ import Bag		( Bag )
 import Maybes		( seqMaybe )
 import Outputable
 import SrcLoc		( SrcLoc, isGoodSrcLoc )
-import Util		( thenCmp )
+import Util		( thenCmp, sortLt )
 import UniqSupply	( UniqSupply )
 \end{code}
 
@@ -144,6 +144,32 @@ data IfaceDecls = IfaceDecls { dcl_tycl  :: [RenamedTyClDecl],	-- Sorted
 			       dcl_rules :: [RenamedRuleDecl],	-- Sorted
 			       dcl_insts :: [RenamedInstDecl] }	-- Unsorted
 
+mkIfaceDecls :: [RenamedTyClDecl] -> [RenamedRuleDecl] -> [RenamedInstDecl] -> IfaceDecls
+mkIfaceDecls tycls rules insts
+  = IfaceDecls { dcl_tycl  = sortLt lt_tycl tycls,
+		 dcl_rules = sortLt lt_rule rules,
+		 dcl_insts = insts }
+  where
+    d1 `lt_tycl` d2 = nameOccName (tyClDeclName      d1) < nameOccName (tyClDeclName      d2)
+    r1 `lt_rule` r2 = nameOccName (ifaceRuleDeclName r1) < nameOccName (ifaceRuleDeclName r2)
+
+	-- I wanted to sort just by the Name, but there's a problem: we are comparing
+	-- the old version of an interface with the new version.  The latter will use
+	-- local names like 'lvl23' that were constructed not by the renamer but by
+	-- the simplifier.  So the unqiues aren't going to line up.
+	--
+	-- It's ok to compare by OccName because this comparison only drives the
+	-- computation of new version numbers.
+	--
+	-- Better solutions: 	Compare in a way that is insensitive to the name used
+	--			for local things.  This would decrease the wobbles due
+	--			to 'lvl23' changing to 'lvl24'.
+	--
+	-- NB: there's a related comparision on MkIface.diffDecls!  
+
+
+
+
 -- typechecker should only look at this, not ModIface
 -- Should be able to construct ModDetails from mi_decls in ModIface
 data ModDetails
diff --git a/ghc/compiler/main/MkIface.lhs b/ghc/compiler/main/MkIface.lhs
index 8540f9f5f4..5ec45f18fe 100644
--- a/ghc/compiler/main/MkIface.lhs
+++ b/ghc/compiler/main/MkIface.lhs
@@ -20,7 +20,8 @@ import BasicTypes	( Fixity(..), NewOrData(..),
 import RnMonad
 import RnHsSyn		( RenamedInstDecl, RenamedTyClDecl )
 import TcHsSyn		( TypecheckedRuleDecl )
-import HscTypes		( VersionInfo(..), IfaceDecls(..), ModIface(..), ModDetails(..),
+import HscTypes		( VersionInfo(..), ModIface(..), ModDetails(..),
+			  IfaceDecls, mkIfaceDecls, dcl_tycl, dcl_rules, dcl_insts,
 			  TyThing(..), DFunId, TypeEnv, isTyClThing, Avails,
 			  WhatsImported(..), GenAvailInfo(..), 
 			  ImportVersion, AvailInfo, Deprecations(..)
@@ -136,10 +137,7 @@ completeIface :: Maybe ModIface		-- The old interface, if we have it
 completeIface maybe_old_iface new_iface mod_details 
   = addVersionInfo maybe_old_iface (new_iface { mi_decls = new_decls })
   where
-     new_decls = IfaceDecls { dcl_tycl  = ty_cls_dcls,
-			      dcl_insts = inst_dcls,
-			      dcl_rules = rule_dcls }
-
+     new_decls   = mkIfaceDecls ty_cls_dcls rule_dcls inst_dcls
      inst_dcls   = map ifaceInstance (md_insts mod_details)
      ty_cls_dcls = foldNameEnv ifaceTyCls [] (md_types mod_details)
      rule_dcls   = map ifaceRule (md_rules mod_details)
@@ -585,7 +583,7 @@ diffDecls old_vers old_fixities new_fixities old new
     diff ok_so_far pp new_vers old []      = (False,     pp, new_vers)
     diff ok_so_far pp new_vers [] (nd:nds) = diff False (pp $$ only_new nd) new_vers [] nds
     diff ok_so_far pp new_vers (od:ods) (nd:nds)
-	= case od_name `compare` nd_name of
+	= case nameOccName od_name `compare` nameOccName nd_name of
 		LT -> diff False (pp $$ only_old od) new_vers ods      (nd:nds)
 		GT -> diff False (pp $$ only_new nd) new_vers (od:ods) nds
 		EQ | od `eq_tc` nd -> diff ok_so_far pp 		   new_vers  ods nds
diff --git a/ghc/compiler/rename/Rename.lhs b/ghc/compiler/rename/Rename.lhs
index edec9523d9..75a8f6f329 100644
--- a/ghc/compiler/rename/Rename.lhs
+++ b/ghc/compiler/rename/Rename.lhs
@@ -27,7 +27,7 @@ import RnIfaces		( slurpImpDecls, mkImportInfo,
 			)
 import RnHiFiles	( readIface, removeContext, 
 			  loadExports, loadFixDecls, loadDeprecs )
-import RnEnv		( availName, 
+import RnEnv		( availsToNameSet,
 			  emptyAvailEnv, unitAvailEnv, availEnvElts, plusAvailEnv, groupAvails,
 			  warnUnusedImports, warnUnusedLocalBinds, warnUnusedModules,
 			  lookupOrigNames, lookupSrcName, newGlobalName
@@ -63,7 +63,8 @@ import Outputable
 import IO		( openFile, IOMode(..) )
 import HscTypes		( PersistentCompilerState, HomeIfaceTable, HomeSymbolTable, 
 			  ModIface(..), WhatsImported(..), 
-			  VersionInfo(..), ImportVersion, IfaceDecls(..),
+			  VersionInfo(..), ImportVersion, 
+			  IfaceDecls, mkIfaceDecls, dcl_tycl, dcl_rules, dcl_insts,
 			  GlobalRdrEnv, AvailEnv, GenAvailInfo(..), AvailInfo, 
 			  Provenance(..), ImportReason(..), initialVersionInfo,
 			  Deprecations(..), lookupDeprec, lookupIface
@@ -136,15 +137,7 @@ rename this_module contents@(HsModule _ _ _ imports local_decls mod_deprec loc)
 	-- SLURP IN ALL THE NEEDED DECLARATIONS
     implicitFVs mod_name rn_local_decls 	`thenRn` \ implicit_fvs -> 
     let
-		-- The export_fvs make the exported names look just as if they
-		-- occurred in the source program.  For the reasoning, see the
-		-- comments with RnIfaces.getImportVersions.
-		-- We only need the 'parent name' of the avail;
-		-- that's enough to suck in the declaration.
-	export_fvs 	= mkNameSet (map availName export_avails)
-	real_source_fvs = source_fvs `plusFV` export_fvs
-
-	slurp_fvs	= implicit_fvs `plusFV` real_source_fvs
+	slurp_fvs	= implicit_fvs `plusFV` source_fvs
 		-- It's important to do the "plus" this way round, so that
 		-- when compiling the prelude, locally-defined (), Bool, etc
 		-- override the implicit ones. 
@@ -188,11 +181,19 @@ rename this_module contents@(HsModule _ _ _ imports local_decls mod_deprec loc)
 				mi_deprecs  = my_deprecs,
 				mi_decls    = panic "mi_decls"
 		    }
+
+		-- The export_fvs make the exported names look just as if they
+		-- occurred in the source program.  
+		-- We only need the 'parent name' of the avail;
+		-- that's enough to suck in the declaration.
+	export_fvs = availsToNameSet export_avails
+	used_vars  = source_fvs `plusFV` export_fvs
+
     in
 
 	-- REPORT UNUSED NAMES, AND DEBUG DUMP 
     reportUnusedNames mod_iface imports global_avail_env
-		      real_source_fvs rn_imp_decls 	`thenRn_`
+		      used_vars rn_imp_decls 			`thenRn_`
 
     returnRn (Just (mod_iface, final_decls))
   where
@@ -425,9 +426,7 @@ loadOldIface parsed_iface
 				vers_rules   = rule_vers,
 				vers_decls   = decls_vers }
 
-	decls = IfaceDecls { dcl_tycl = new_decls,
-			     dcl_rules = new_rules,
-			     dcl_insts = new_insts }
+	decls = mkIfaceDecls new_decls new_rules new_insts
 
  	mod_iface = ModIface { mi_module = mod, mi_version = version,
 			       mi_exports = avails, mi_usages  = usages,
diff --git a/ghc/compiler/rename/RnHsSyn.lhs b/ghc/compiler/rename/RnHsSyn.lhs
index fefcf7c325..dc4bd87fea 100644
--- a/ghc/compiler/rename/RnHsSyn.lhs
+++ b/ghc/compiler/rename/RnHsSyn.lhs
@@ -162,9 +162,9 @@ instDeclFVs (InstDecl inst_ty _ _ maybe_dfun _)
 
 ----------------
 ruleDeclFVs (HsRule _ _ _ _ _ _) = emptyFVs
-ruleDeclFVs (IfaceRule _ vars _ _ rhs _)
+ruleDeclFVs (IfaceRule _ vars _ args rhs _)
   = delFVs (map ufBinderName vars) $
-    ufExprFVs rhs
+    ufExprFVs rhs `plusFV` plusFVs (map ufExprFVs args)
 
 ----------------
 conDeclFVs (ConDecl _ _ tyvars context details _)
diff --git a/ghc/compiler/rename/RnIfaces.lhs b/ghc/compiler/rename/RnIfaces.lhs
index 91ce7596e0..d4a6f32cf0 100644
--- a/ghc/compiler/rename/RnIfaces.lhs
+++ b/ghc/compiler/rename/RnIfaces.lhs
@@ -85,53 +85,14 @@ getInterfaceExports mod_name from
 %*							*
 %*********************************************************
 
-getImportVersions figures out what the ``usage information'' for this
+mkImportInof figures out what the ``usage information'' for this
 moudule is; that is, what it must record in its interface file as the
-things it uses.  It records:
-
-\begin{itemize}
-\item	(a) anything reachable from its body code
-\item	(b) any module exported with a @module Foo@
-\item   (c) anything reachable from an exported item
-\end{itemize}
-
-Why (b)?  Because if @Foo@ changes then this module's export list
-will change, so we must recompile this module at least as far as
-making a new interface file --- but in practice that means complete
-recompilation.
-
-Why (c)?  Consider this:
-\begin{verbatim}
-	module A( f, g ) where	|	module B( f ) where
-	  import B( f )		|	  f = h 3
-	  g = ...		|	  h = ...
-\end{verbatim}
-
-Here, @B.f@ isn't used in A.  Should we nevertheless record @B.f@ in
-@A@'s usages?  Our idea is that we aren't going to touch A.hi if it is
-*identical* to what it was before.  If anything about @B.f@ changes
-than anyone who imports @A@ should be recompiled in case they use
-@B.f@ (they'll get an early exit if they don't).  So, if anything
-about @B.f@ changes we'd better make sure that something in A.hi
-changes, and the convenient way to do that is to record the version
-number @B.f@ in A.hi in the usage list.  If B.f changes that'll force a
-complete recompiation of A, which is overkill but it's the only way to 
-write a new, slightly different, A.hi.
-
-But the example is tricker.  Even if @B.f@ doesn't change at all,
-@B.h@ may do so, and this change may not be reflected in @f@'s version
-number.  But with -O, a module that imports A must be recompiled if
-@B.h@ changes!  So A must record a dependency on @B.h@.  So we treat
-the occurrence of @B.f@ in the export list *just as if* it were in the
-code of A, and thereby haul in all the stuff reachable from it.
-
-[NB: If B was compiled with -O, but A isn't, we should really *still*
-haul in all the unfoldings for B, in case the module that imports A *is*
-compiled with -O.  I think this is the case.]
-
-Even if B is used at all we get a usage line for B
-	import B <n> :: ... ;
-in A.hi, to record the fact that A does import B.  This is used to decide
+things it uses.  
+
+We produce a line for every module B below the module, A, currently being
+compiled:
+	import B <n> ;
+to record the fact that A does import B indireclty.  This is used to decide
 to look to look for B.hi rather than B.hi-boot when compiling a module that
 imports A.  This line says that A imports B, but uses nothing in it.
 So we'll get an early bale-out when compiling A if B's version changes.
@@ -317,8 +278,12 @@ closeDecls decls needed
     case rule_decls of
 	[]    -> returnRn decls	-- No new rules, so we are done
 	other -> rnIfaceDecls rnIfaceRuleDecl rule_decls	`thenRn` \ rule_decls' ->
-		 closeDecls (map RuleD rule_decls' ++ decls)
-			    (plusFVs (map ruleDeclFVs rule_decls'))
+		 let
+			rule_fvs = plusFVs (map ruleDeclFVs rule_decls')
+		 in
+		 traceRn (text "closeRules" <+> ppr rule_decls' $$ fsep (map ppr (nameSetToList rule_fvs)))	`thenRn_`
+		 closeDecls (map RuleD rule_decls' ++ decls) rule_fvs
+
 		 
 
 -------------------------------------------------------
@@ -644,7 +609,13 @@ importDecl name
 	returnRn AlreadySlurped
     else
 
-	-- STEP 2: Check if it's already in the type environment
+	-- STEP 2: Check if we've slurped it in while compiling this module
+    getIfacesRn				`thenRn` \ ifaces ->
+    if name `elemNameSet` iSlurp ifaces then	
+	returnRn AlreadySlurped	
+    else
+
+	-- STEP 3: Check if it's already in the type environment
     getTypeEnvRn 			`thenRn` \ lookup ->
     case lookup name of {
 	Just ty_thing | name `elemNameEnv` wiredInThingEnv
@@ -658,12 +629,6 @@ importDecl name
 
 	Nothing -> 
 
-	-- STEP 3: Check if we've slurped it in while compiling this module
-    getIfacesRn				`thenRn` \ ifaces ->
-    if name `elemNameSet` iSlurp ifaces then	
-	returnRn AlreadySlurped	
-    else
-
 	-- STEP 4: OK, we have to slurp it in from an interface file
 	--	   First load the interface file
     traceRn nd_doc			`thenRn_`
@@ -711,11 +676,11 @@ recompileRequired :: FilePath		-- Only needed for debug msgs
 		  -> ModIface 		-- Old interface
 		  -> RnMG RecompileRequired
 recompileRequired iface_path source_unchanged iface
-  = traceRn (text "Considering whether compilation is required for" <+> text iface_path <> colon)	`thenRn_`
+  = traceHiDiffsRn (text "Considering whether compilation is required for" <+> text iface_path <> colon)	`thenRn_`
 
 	-- CHECK WHETHER THE SOURCE HAS CHANGED
     if not source_unchanged then
-	traceRn (nest 4 (text "Source file changed or recompilation check turned off"))	`thenRn_` 
+	traceHiDiffsRn (nest 4 (text "Source file changed or recompilation check turned off"))	`thenRn_` 
 	returnRn outOfDate
     else
 
@@ -819,8 +784,8 @@ checkEntityUsage new_vers (name,old_vers)
 	  | new_vers == old_vers -> returnRn upToDate
 	  | otherwise	 	 -> out_of_date (sep [ptext SLIT("Out of date:"), ppr name])
 
-up_to_date  msg = traceRn msg `thenRn_` returnRn upToDate
-out_of_date msg = traceRn msg `thenRn_` returnRn outOfDate
+up_to_date  msg = traceHiDiffsRn msg `thenRn_` returnRn upToDate
+out_of_date msg = traceHiDiffsRn msg `thenRn_` returnRn outOfDate
 \end{code}
 
 
diff --git a/ghc/compiler/rename/RnMonad.lhs b/ghc/compiler/rename/RnMonad.lhs
index 0d562d3114..b5978923f7 100644
--- a/ghc/compiler/rename/RnMonad.lhs
+++ b/ghc/compiler/rename/RnMonad.lhs
@@ -96,6 +96,11 @@ traceRn msg
    = doptRn Opt_D_dump_rn_trace `thenRn` \b ->
      if b then putDocRn msg else returnRn ()
 
+traceHiDiffsRn :: SDoc -> RnM d ()
+traceHiDiffsRn msg
+   = doptRn Opt_D_dump_hi_diffs `thenRn` \b ->
+     if b then putDocRn msg else returnRn ()
+
 putDocRn :: SDoc -> RnM d ()
 putDocRn msg = ioToRnM (printErrs msg)	`thenRn_`
 	       returnRn ()
diff --git a/ghc/compiler/simplCore/BinderInfo.lhs b/ghc/compiler/simplCore/BinderInfo.lhs
index 1623bcd702..d98ea9e4a6 100644
--- a/ghc/compiler/simplCore/BinderInfo.lhs
+++ b/ghc/compiler/simplCore/BinderInfo.lhs
@@ -24,8 +24,7 @@ module BinderInfo (
 
 #include "HsVersions.h"
 
-import IdInfo		( OccInfo(..), InsideLam, OneBranch, insideLam, notInsideLam, oneBranch )
-import GlaExts		( Int(..), (+#) )
+import IdInfo		( OccInfo(..), InsideLam, insideLam, notInsideLam )
 import Outputable
 \end{code}
 
diff --git a/ghc/compiler/stranal/SaAbsInt.lhs b/ghc/compiler/stranal/SaAbsInt.lhs
index 3d209c965d..47afd991c4 100644
--- a/ghc/compiler/stranal/SaAbsInt.lhs
+++ b/ghc/compiler/stranal/SaAbsInt.lhs
@@ -17,16 +17,16 @@ module SaAbsInt (
 
 import CmdLineOpts	( opt_AllStrict, opt_NumbersStrict )
 import CoreSyn
-import CoreUnfold	( Unfolding, maybeUnfoldingTemplate )
-import Id		( Id, idType, idArity, idStrictness, idUnfolding, isDataConId_maybe )
+import CoreUnfold	( maybeUnfoldingTemplate )
+import Id		( Id, idType, idStrictness, idUnfolding, isDataConId_maybe )
 import DataCon		( dataConTyCon, splitProductType_maybe, dataConRepArgTys )
 import IdInfo		( StrictnessInfo(..) )
-import Demand		( Demand(..), wwPrim, wwStrict, wwEnum, wwUnpackData, wwLazy, wwUnpackNew,
+import Demand		( Demand(..), wwPrim, wwStrict, wwUnpackData, wwLazy, wwUnpackNew,
 			  mkStrictnessInfo, isLazy
 			)
 import SaLib
-import TyCon		( isProductTyCon, isRecursiveTyCon, isEnumerationTyCon, isNewTyCon )
-import BasicTypes	( Arity, NewOrData(..) )
+import TyCon		( isProductTyCon, isRecursiveTyCon, isNewTyCon )
+import BasicTypes	( NewOrData(..) )
 import Type		( splitTyConApp_maybe, 
 		          isUnLiftedType, Type )
 import TyCon		( tyConUnique )
diff --git a/ghc/compiler/typecheck/TcEnv.lhs b/ghc/compiler/typecheck/TcEnv.lhs
index bf2ef1d3d0..ba28d13456 100644
--- a/ghc/compiler/typecheck/TcEnv.lhs
+++ b/ghc/compiler/typecheck/TcEnv.lhs
@@ -165,7 +165,7 @@ getTcGEnv (TcEnv { tcGEnv = genv }) = genv
 -- This data type is used to help tie the knot
 -- when type checking type and class declarations
 data TyThingDetails = SynTyDetails Type
-		    | DataTyDetails ClassContext [DataCon] [Class]
+		    | DataTyDetails ClassContext [DataCon]
 		    | ClassDetails ClassContext [Id] [ClassOpItem] DataCon
 \end{code}
 
diff --git a/ghc/compiler/typecheck/TcModule.lhs b/ghc/compiler/typecheck/TcModule.lhs
index bc1a87d09a..7e63ec1f4a 100644
--- a/ghc/compiler/typecheck/TcModule.lhs
+++ b/ghc/compiler/typecheck/TcModule.lhs
@@ -131,6 +131,7 @@ tcModule :: PersistentCompilerState
 
 tcModule pcs hst get_fixity this_mod decls unf_env
   = 		 -- Type-check the type and class decls
+    traceTc (text "Tc1")	`thenTc_`
     tcTyAndClassDecls unf_env decls		`thenTc` \ env ->
     tcSetEnv env 				$
     let
@@ -139,12 +140,14 @@ tcModule pcs hst get_fixity this_mod decls unf_env
     in
     
     	-- Typecheck the instance decls, includes deriving
+    traceTc (text "Tc2")	`thenTc_`
     tcInstDecls1 (pcs_insts pcs) (pcs_PRS pcs) 
 		 hst unf_env get_fixity this_mod 
 		 tycons decls		`thenTc` \ (new_pcs_insts, inst_env, local_inst_info, deriv_binds) ->
     tcSetInstEnv inst_env			$
     
         -- Default declarations
+    traceTc (text "Tc3")	`thenTc_`
     tcDefaults decls				`thenTc` \ defaulting_tys ->
     tcSetDefaultTys defaulting_tys 		$
     
@@ -157,7 +160,9 @@ tcModule pcs hst get_fixity this_mod decls unf_env
     -- We must do this before mkImplicitDataBinds (which comes next), since
     -- the latter looks up unpackCStringId, for example, which is usually 
     -- imported
+    traceTc (text "Tc3")	`thenTc_`
     tcInterfaceSigs unf_env decls		`thenTc` \ sig_ids ->
+    traceTc (text "Tc5")	`thenTc_` (
     tcExtendGlobalValEnv sig_ids		$
     tcGetEnv					`thenTc` \ unf_env ->
     
@@ -180,15 +185,18 @@ tcModule pcs hst get_fixity this_mod decls unf_env
     tcExtendGlobalValEnv cls_ids		$
     
         -- Foreign import declarations next
+    traceTc (text "Tc6")	`thenTc_`
     tcForeignImports decls			`thenTc`    \ (fo_ids, foi_decls) ->
     tcExtendGlobalValEnv fo_ids			$
     
     -- Value declarations next.
     -- We also typecheck any extra binds that came out of the "deriving" process
+    traceTc (text "Tc7")	`thenTc_`
     tcTopBinds (get_binds decls `ThenBinds` deriv_binds)	`thenTc` \ ((val_binds, env), lie_valdecls) ->
     tcSetEnv env $
     
         -- Foreign export declarations next
+    traceTc (text "Tc8")	`thenTc_`
     tcForeignExports decls		`thenTc`    \ (lie_fodecls, foe_binds, foe_decls) ->
     
     	-- Second pass over class and instance declarations,
@@ -253,6 +261,7 @@ tcModule pcs hst get_fixity this_mod decls unf_env
 			  tc_fords   = foi_decls ++ foe_decls',
 			  tc_rules   = local_rules'
                         })
+    )
 
 get_binds decls = foldr ThenBinds EmptyBinds [binds | ValD binds <- decls]
 \end{code}
diff --git a/ghc/compiler/typecheck/TcTyClsDecls.lhs b/ghc/compiler/typecheck/TcTyClsDecls.lhs
index b92276e023..6cd8799f87 100644
--- a/ghc/compiler/typecheck/TcTyClsDecls.lhs
+++ b/ghc/compiler/typecheck/TcTyClsDecls.lhs
@@ -10,6 +10,7 @@ module TcTyClsDecls (
 
 #include "HsVersions.h"
 
+import CmdLineOpts	( DynFlags, DynFlag(..), dopt )
 import HsSyn		( HsDecl(..), TyClDecl(..),
 			  HsTyVarBndr,
 			  ConDecl(..), 
@@ -47,7 +48,6 @@ import Maybes		( mapMaybe )
 import ErrUtils		( Message )
 import HsDecls          ( getClassDeclSysNames )
 import Generics         ( mkTyConGenInfo )
-import CmdLineOpts	( DynFlags )
 \end{code}
 
 
@@ -296,11 +296,12 @@ buildTyConOrClass dflags is_rec kenv rec_vrcs  rec_details
   where
 	tycon = mkAlgTyConRep tycon_name tycon_kind tyvars ctxt argvrcs
 			   data_cons nconstrs
-			   derived_classes
 			   flavour is_rec gen_info
-	gen_info = mkTyConGenInfo dflags tycon name1 name2
 
-	DataTyDetails ctxt data_cons derived_classes = lookupNameEnv_NF rec_details tycon_name
+	gen_info | not (dopt Opt_Generics dflags) = Nothing
+		 | otherwise = mkTyConGenInfo tycon name1 name2
+
+	DataTyDetails ctxt data_cons = lookupNameEnv_NF rec_details tycon_name
 
 	tycon_kind = lookupNameEnv_NF kenv tycon_name
 	tyvars	   = mkTyClTyVars tycon_kind tyvar_names
diff --git a/ghc/compiler/typecheck/TcTyDecls.lhs b/ghc/compiler/typecheck/TcTyDecls.lhs
index 24896abd49..76b91d5223 100644
--- a/ghc/compiler/typecheck/TcTyDecls.lhs
+++ b/ghc/compiler/typecheck/TcTyDecls.lhs
@@ -24,7 +24,7 @@ import TcMonoType	( tcHsType, tcHsSigType, tcHsBoxedSigType, tcHsTyVars, tcClass
 			  kcHsContext, kcHsSigType
 			)
 import TcEnv		( tcExtendTyVarEnv, 
-			  tcLookupTyCon, tcLookupClass, tcLookupGlobalId, 
+			  tcLookupTyCon, tcLookupGlobalId, 
 			  TyThingDetails(..)
 			)
 import TcMonad
diff --git a/ghc/compiler/typecheck/TcUnify.lhs b/ghc/compiler/typecheck/TcUnify.lhs
index 8289392c23..0944e639f7 100644
--- a/ghc/compiler/typecheck/TcUnify.lhs
+++ b/ghc/compiler/typecheck/TcUnify.lhs
@@ -324,7 +324,6 @@ uUnboundVar swapped tv1 maybe_ty1 ps_ty2 ty2@(TyVarTy tv2)
 uUnboundVar swapped tv1 maybe_ty1 ps_ty2 non_var_ty2
   = checkKinds swapped tv1 non_var_ty2			`thenTc_`
     occur_check non_var_ty2				`thenTc_`
-    ASSERT( isNotUsgTy ps_ty2 )
     checkTcM (not (isSigTyVar tv1))
 	     (failWithTcM (unifyWithSigErr tv1 ps_ty2))	`thenTc_`
 
diff --git a/ghc/compiler/types/Generics.hi-boot-5 b/ghc/compiler/types/Generics.hi-boot-5
index 3a9ab2ceda..f57436d6a0 100644
--- a/ghc/compiler/types/Generics.hi-boot-5
+++ b/ghc/compiler/types/Generics.hi-boot-5
@@ -1,4 +1,4 @@
 __interface Generics 1 0 where
 __export Generics mkTyConGenInfo ;
 
-1 mkTyConGenInfo ::  TyCon.TyCon -> Name.Name -> Name.Name -> PrelMaybe.Maybe (BasicTypes.EP Var.Id) ;
+2 mkTyConGenInfo ::  TyCon.TyCon -> Name.Name -> Name.Name -> PrelMaybe.Maybe (BasicTypes.EP Var.Id) ;
diff --git a/ghc/compiler/types/Generics.lhs b/ghc/compiler/types/Generics.lhs
index 6c48a1fb27..89e36c4fa1 100644
--- a/ghc/compiler/types/Generics.lhs
+++ b/ghc/compiler/types/Generics.lhs
@@ -4,7 +4,6 @@ module Generics ( mkTyConGenInfo, mkGenericRhs,
     ) where
 
 
-import CmdLineOpts	( DynFlags, DynFlag(..), dopt )
 import RnHsSyn		( RenamedHsExpr )
 import HsSyn		( HsExpr(..), InPat(..), mkSimpleMatch )
 
@@ -219,7 +218,7 @@ valid ty
 %************************************************************************
 
 \begin{code}
-mkTyConGenInfo :: DynFlags -> TyCon -> Name -> Name -> Maybe (EP Id)
+mkTyConGenInfo :: TyCon -> Name -> Name -> Maybe (EP Id)
 -- mkTyConGenInfo is called twice
 --	once from TysWiredIn for Tuples
 --	once the typechecker TcTyDecls 
@@ -230,10 +229,7 @@ mkTyConGenInfo :: DynFlags -> TyCon -> Name -> Name -> Maybe (EP Id)
 -- The two names are the names constructed by the renamer
 -- for the fromT and toT conversion functions.
 
-mkTyConGenInfo dflags tycon from_name to_name
-  | not (dopt Opt_Generics dflags)
-  = Nothing
-
+mkTyConGenInfo tycon from_name to_name
   | null datacons 	-- Abstractly imported types don't have
   = Nothing		-- to/from operations, (and should not need them)
 
diff --git a/ghc/compiler/types/InstEnv.lhs b/ghc/compiler/types/InstEnv.lhs
index 7ca6cf6007..ad2bd1f9b5 100644
--- a/ghc/compiler/types/InstEnv.lhs
+++ b/ghc/compiler/types/InstEnv.lhs
@@ -26,7 +26,6 @@ import Type		( Type, splitTyConApp_maybe,
 			  splitSigmaTy, splitDFunTy, tyVarsOfTypes
 			)
 import PprType		( )
-import DataCon		( DataCon )
 import TyCon		( TyCon )
 import Outputable
 import Unify		( matchTys, unifyTyListsX )
diff --git a/ghc/compiler/types/Variance.lhs b/ghc/compiler/types/Variance.lhs
index 57119ff988..724d9d8cff 100644
--- a/ghc/compiler/types/Variance.lhs
+++ b/ghc/compiler/types/Variance.lhs
@@ -12,14 +12,13 @@ module Variance(
 #include "HsVersions.h"
 
 import TypeRep          ( Type(..), TyNote(..) )  -- friend
-import TyCon            ( TyCon, ArgVrcs, tyConKind, tyConArity, tyConDataConsIfAvailable, tyConTyVars,
+import TyCon            ( TyCon, ArgVrcs, tyConArity, tyConDataConsIfAvailable, tyConTyVars,
                           tyConArgVrcs_maybe, getSynTyConDefn, isSynTyCon, isAlgTyCon )
 import DataCon          ( dataConRepArgTys )
 
 import FiniteMap
 import Var              ( TyVar )
 import VarSet
-import Name             ( Name, getName )
 import Maybes           ( expectJust )
 import Outputable
 \end{code}
diff --git a/ghc/compiler/utils/FiniteMap.lhs b/ghc/compiler/utils/FiniteMap.lhs
index cb7da6d2be..b4c4f60faa 100644
--- a/ghc/compiler/utils/FiniteMap.lhs
+++ b/ghc/compiler/utils/FiniteMap.lhs
@@ -57,9 +57,7 @@ module FiniteMap (
 #define OUTPUTABLE_key {--}
 #endif
 
-import {-# SOURCE #-} Name ( Name )
 import GlaExts
-import FastString
 import Maybes
 import Bag	  ( Bag, foldrBag )
 import Outputable
@@ -587,8 +585,6 @@ glueVBal fm_l@(Branch key_l elt_l _ fm_ll fm_lr)
   | otherwise		-- We now need the same two cases as in glueBal above.
   = glueBal fm_l fm_r
   where
-    (mid_key_l,mid_elt_l) = findMax fm_l
-    (mid_key_r,mid_elt_r) = findMin fm_r
     size_l = sizeFM fm_l
     size_r = sizeFM fm_r
 \end{code}
diff --git a/ghc/compiler/utils/Outputable.lhs b/ghc/compiler/utils/Outputable.lhs
index 5f38e9b896..9cb9fa8edc 100644
--- a/ghc/compiler/utils/Outputable.lhs
+++ b/ghc/compiler/utils/Outputable.lhs
@@ -55,8 +55,6 @@ import FastString
 import qualified Pretty
 import Pretty		( Doc, Mode(..), TextDetails(..), fullRender )
 import Panic
-import ST		( runST )
-import Foreign
 import Char             ( chr, ord, isDigit )
 \end{code}
 
diff --git a/ghc/compiler/utils/StringBuffer.lhs b/ghc/compiler/utils/StringBuffer.lhs
index 84bfeb334b..8fe48e084f 100644
--- a/ghc/compiler/utils/StringBuffer.lhs
+++ b/ghc/compiler/utils/StringBuffer.lhs
@@ -68,7 +68,6 @@ module StringBuffer
 import GlaExts
 import PrelAddr 	( Addr(..) )
 import Foreign
-import ST
 import Char		( chr )
 
 -- urk!
diff --git a/ghc/compiler/utils/UnicodeUtil.lhs b/ghc/compiler/utils/UnicodeUtil.lhs
index 0123e67305..64062dd3c7 100644
--- a/ghc/compiler/utils/UnicodeUtil.lhs
+++ b/ghc/compiler/utils/UnicodeUtil.lhs
@@ -7,8 +7,8 @@ module UnicodeUtil(
 
 #include "HsVersions.h"
 
-import Panic (panic)
-import Char  (chr, ord)
+import Panic ( panic )
+import Char  ( chr )
 \end{code}
 
 \begin{code}