[project @ 2005-07-25 11:08:26 by simonpj]

MERGE TO STABLE if poss

Make the "root main" Id :Main.main into an *implicit* Id, whose parent is
Main.main.  What that means is that the "root main" Id won't be emitted
into the interface file.  Which has not been causing a problem in practice
but is clearly wrong -- there were two 'main's in the interface file.

diff --git a/ghc/compiler/prelude/PrelNames.lhs b/ghc/compiler/prelude/PrelNames.lhs
index 13b862a..0d7d558 100644 (file)
--- a/ghc/compiler/prelude/PrelNames.lhs
+++ b/ghc/compiler/prelude/PrelNames.lhs
@@ -268,7 +268,7 @@ rANDOM              = mkModule "System.Random"
 
 gLA_EXTS       = mkModule "GHC.Exts"
 rOOT_MAIN      = mkModule ":Main"              -- Root module for initialisation 
-       -- The ':xxx' makes a moudle name that the user can never
+       -- The ':xxx' makes a module name that the user can never
        -- use himself.  The z-encoding for ':' is "ZC", so the z-encoded
        -- module name still starts with a capital letter, which keeps
        -- the z-encoded version consistent.
@@ -435,7 +435,6 @@ and it's convenient to write them all down in one place.
 
 
 \begin{code}
-rootMainName  = varQual rOOT_MAIN FSLIT("main") rootMainKey
 runMainIOName = varQual pREL_TOP_HANDLER FSLIT("runMainIO") runMainKey
 
 orderingTyConName = tcQual   pREL_BASE FSLIT("Ordering") orderingTyConKey

diff --git a/ghc/compiler/typecheck/TcRnDriver.lhs b/ghc/compiler/typecheck/TcRnDriver.lhs
index 8e427fe..c9f03c3 100644 (file)
--- a/ghc/compiler/typecheck/TcRnDriver.lhs
+++ b/ghc/compiler/typecheck/TcRnDriver.lhs
@@ -33,7 +33,7 @@ import HsSyn          ( HsModule(..), HsExtCore(..), HsGroup(..), LHsDecl,
                          nlHsApp, nlHsVar, pprLHsBinds )
 import RdrHsSyn                ( findSplice )
 
-import PrelNames       ( runMainIOName, rootMainName, mAIN,
+import PrelNames       ( runMainIOName, rootMainKey, rOOT_MAIN, mAIN,
                          main_RDR_Unqual )
 import RdrName         ( RdrName, mkRdrUnqual, emptyGlobalRdrEnv )
 import TcHsSyn         ( zonkTopDecls )
@@ -63,8 +63,9 @@ import ErrUtils               ( Messages, mkDumpDoc, showPass )
 import Id              ( Id, mkExportedLocalId, isLocalId, idName, idType )
 import Var             ( Var )
 import Module           ( Module, ModuleEnv, mkModule, moduleEnvElts, elemModuleEnv )
-import OccName         ( mkVarOcc )
-import Name            ( Name, NamedThing(..), isExternalName, getSrcLoc, isWiredInName )
+import OccName         ( mkVarOcc, mkOccFS, varName )
+import Name            ( Name, NamedThing(..), isExternalName, getSrcLoc, isWiredInName,
+                         mkExternalName )
 import NameSet
 import TyCon           ( tyConHasGenerics, isSynTyCon, getSynTyConDefn, tyConKind )
 import SrcLoc          ( srcLocSpan, Located(..), noLoc )
@@ -83,7 +84,7 @@ import Outputable
 #ifdef GHCI
 import HsSyn           ( HsStmtContext(..), Stmt(..), HsExpr(..), 
                          HsLocalBinds(..), HsValBinds(..),
-                         LStmt, LHsExpr, LHsType, mkVarBind,
+                         LStmt, LHsExpr, LHsType, mkVarBind, 
                          collectLStmtsBinders, collectLStmtBinders, nlVarPat,
                          placeHolderType, noSyntaxExpr )
 import RdrName         ( GlobalRdrElt(..), globalRdrEnvElts,
@@ -764,8 +765,23 @@ check_main ghci_mode tcg_env main_mod main_fn
        ; (main_expr, ty) <- setSrcSpan (srcLocSpan (getSrcLoc main_name)) $
                             tcInferRho rhs
 
-       ; let { root_main_id = mkExportedLocalId rootMainName ty ;
-               main_bind    = noLoc (VarBind root_main_id main_expr) }
+       -- 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 
+                                  (mkOccFS varName FSLIT("main")) 
+                                  (Just main_name) (getSrcLoc main_name)
+             ; root_main_id = mkExportedLocalId root_main_name ty
+             ; main_bind    = noLoc (VarBind root_main_id main_expr) }
 
        ; return (tcg_env { tcg_binds = tcg_binds tcg_env 
                                        `snocBag` main_bind,