[project @ 2006-01-17 13:50:06 by simonmar]

[ghc-hetmet.git] / ghc / compiler / rename / RnSource.lhs

diff --git a/ghc/compiler/rename/RnSource.lhs b/ghc/compiler/rename/RnSource.lhs
index c113af7..4bb9bd0 100644 (file)
--- a/ghc/compiler/rename/RnSource.lhs
+++ b/ghc/compiler/rename/RnSource.lhs
@@ -15,7 +15,8 @@ module RnSource (
 import {-# SOURCE #-} RnExpr( rnLExpr )
 
 import HsSyn
-import RdrName         ( RdrName, isRdrDataCon, elemLocalRdrEnv )
+import RdrName         ( RdrName, isRdrDataCon, elemLocalRdrEnv, globalRdrEnvElts,
+                         GlobalRdrElt(..), isLocalGRE )
 import RdrHsSyn                ( extractGenericPatTyVars, extractHsRhoRdrTyVars )
 import RnHsSyn
 import RnTypes         ( rnLHsType, rnLHsTypes, rnHsSigType, rnHsTypeFVs, rnContext )
@@ -35,6 +36,7 @@ import Class          ( FunDep )
 import Name            ( Name, nameOccName )
 import NameSet
 import NameEnv
+import OccName         ( occEnvElts )
 import Outputable
 import SrcLoc          ( Located(..), unLoc, getLoc, noLoc )
 import DynFlags        ( DynFlag(..) )
@@ -502,7 +504,7 @@ rnTyClDecl (ClassDecl {tcdCtxt = context, tcdLName = cname,
        -- Check the signatures
        -- First process the class op sigs (op_sigs), then the fixity sigs (non_op_sigs).
     let
-       sig_rdr_names_w_locs   = [op | L _ (Sig op _) <- sigs]
+       sig_rdr_names_w_locs   = [op | L _ (TypeSig op _) <- sigs]
     in
     checkDupNames sig_doc sig_rdr_names_w_locs `thenM_` 
        -- Typechecker is responsible for checking that we only
@@ -661,14 +663,41 @@ rnHsTyvar doc tyvar = lookupOccRn tyvar
 %*                                                     *
 %*********************************************************
 
+Note [Splices]
+~~~~~~~~~~~~~~
+Consider
+       f = ...
+       h = ...$(thing "f")...
+
+The splice can expand into literally anything, so when we do dependency
+analysis we must assume that it might mention 'f'.  So we simply treat
+all locally-defined names as mentioned by any splice.  This is terribly
+brutal, but I don't see what else to do.  For example, it'll mean
+that every locally-defined thing will appear to be used, so no unused-binding
+warnings.  But if we miss the dependency, then we might typecheck 'h' before 'f',
+and that will crash the type checker because 'f' isn't in scope.
+
+Currently, I'm not treating a splice as also mentioning every import,
+which is a bit inconsistent -- but there are a lot of them.  We might
+thereby get some bogus unused-import warnings, but we won't crash the
+type checker.  Not very satisfactory really.
+
 \begin{code}
 rnSplice :: HsSplice RdrName -> RnM (HsSplice Name, FreeVars)
 rnSplice (HsSplice n expr)
-  = checkTH expr "splice"      `thenM_`
-    getSrcSpanM                `thenM` \ loc ->
-    newLocalsRn [L loc n]      `thenM` \ [n'] ->
-    rnLExpr expr               `thenM` \ (expr', fvs) ->
-    returnM (HsSplice n' expr', fvs)
+  = do { checkTH expr "splice"
+       ; loc  <- getSrcSpanM
+       ; [n'] <- newLocalsRn [L loc n]
+       ; (expr', fvs) <- rnLExpr expr
+
+       -- Ugh!  See Note [Splices] above
+       ; lcl_rdr <- getLocalRdrEnv
+       ; gbl_rdr <- getGlobalRdrEnv
+       ; let gbl_names = mkNameSet [gre_name gre | gre <- globalRdrEnvElts gbl_rdr, 
+                                                   isLocalGRE gre]
+             lcl_names = mkNameSet (occEnvElts lcl_rdr)
+
+       ; return (HsSplice n' expr', fvs `plusFV` lcl_names `plusFV` gbl_names) }
 
 #ifdef GHCI 
 checkTH e what = returnM ()    -- OK