[project @ 2004-12-23 11:50:55 by simonpj]

Enable scoped type variables only where there is an explicit forall

diff --git a/ghc/compiler/parser/Lexer.x b/ghc/compiler/parser/Lexer.x
index 1d0a5e7..0a2f3c5 100644 (file)
--- a/ghc/compiler/parser/Lexer.x
+++ b/ghc/compiler/parser/Lexer.x
@@ -506,7 +506,7 @@ reservedWordsFM = listToUFM $
        ( "where",      ITwhere,        0 ),
        ( "_scc_",      ITscc,          0 ),            -- ToDo: remove
 
-       ( "forall",     ITforall,        bit glaExtsBit),
+       ( "forall",     ITforall,        bit tvBit),
        ( "mdo",        ITmdo,           bit glaExtsBit),
 
        ( "foreign",    ITforeign,       bit ffiBit),
@@ -542,7 +542,7 @@ reservedSymsFM = listToUFM $
        ,("!",  ITbang,         0)
 
        ,("*",  ITstar,         bit glaExtsBit) -- For data T (a::*) = MkT
-       ,(".",  ITdot,          bit glaExtsBit) -- For 'forall a . t'
+       ,(".",  ITdot,          bit tvBit)      -- For 'forall a . t'
 
        ,("-<", ITlarrowtail,   bit arrowsBit)
        ,(">-", ITrarrowtail,   bit arrowsBit)
@@ -1160,6 +1160,7 @@ parrBit      = 2
 arrowsBit  = 4
 thBit     = 5
 ipBit      = 6
+tvBit     = 7  -- Scoped type variables enables 'forall' keyword
 
 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
 glaExtsEnabled flags = testBit flags glaExtsBit
@@ -1168,6 +1169,7 @@ parrEnabled    flags = testBit flags parrBit
 arrowsEnabled  flags = testBit flags arrowsBit
 thEnabled      flags = testBit flags thBit
 ipEnabled      flags = testBit flags ipBit
+tvEnabled      flags = testBit flags tvBit
 
 -- create a parse state
 --
@@ -1190,6 +1192,7 @@ mkPState buf loc flags  =
               .|. arrowsBit  `setBitIf` dopt Opt_Arrows      flags
               .|. thBit      `setBitIf` dopt Opt_TH          flags
               .|. ipBit      `setBitIf` dopt Opt_ImplicitParams flags
+              .|. tvBit      `setBitIf` dopt Opt_ScopedTypeVariables flags
       --
       setBitIf :: Int -> Bool -> Int
       b `setBitIf` cond | cond      = bit b

diff --git a/ghc/compiler/rename/RnEnv.lhs b/ghc/compiler/rename/RnEnv.lhs
index d43a4e3..710bd6e 100644 (file)
--- a/ghc/compiler/rename/RnEnv.lhs
+++ b/ghc/compiler/rename/RnEnv.lhs
@@ -644,7 +644,9 @@ bindSigTyVarsFV sigs thing_inside
                bindLocalNamesFV tvs thing_inside }
   where
     tvs = [ hsLTyVarName ltv 
-         | L _ (Sig _ (L _ (HsForAllTy _ ltvs _ _))) <- sigs, ltv <- ltvs ]
+         | L _ (Sig _ (L _ (HsForAllTy Explicit ltvs _ _))) <- sigs, ltv <- ltvs ]
+       -- Note the pattern-match on "Explicit"; we only bind
+       -- type variables from signatures with an explicit top-level for-all
                                
 
 extendTyVarEnvFVRn :: [Name] -> RnM (a, FreeVars) -> RnM (a, FreeVars)