Emit a decent error message when there is a decl-splice inside a decl-bracket

[ghc-hetmet.git] / compiler / parser / RdrHsSyn.lhs

diff --git a/compiler/parser/RdrHsSyn.lhs b/compiler/parser/RdrHsSyn.lhs
index c29f23a..7a6a0e9 100644 (file)
--- a/compiler/parser/RdrHsSyn.lhs
+++ b/compiler/parser/RdrHsSyn.lhs
@@ -17,7 +17,7 @@ module RdrHsSyn (
        cvBindGroup,
         cvBindsAndSigs,
        cvTopDecls,
-       findSplice, mkGroup,
+       findSplice, checkDecBrGroup,
 
        -- Stuff to do with Foreign declarations
        CallConv(..),
@@ -281,14 +281,15 @@ has_args ((L _ (Match args _ _)) : _) = not (null args)
 findSplice :: [LHsDecl a] -> (HsGroup a, Maybe (SpliceDecl a, [LHsDecl a]))
 findSplice ds = addl emptyRdrGroup ds
 
-mkGroup :: [LHsDecl a] -> HsGroup a
-mkGroup ds = addImpDecls emptyRdrGroup ds
-
-addImpDecls :: HsGroup a -> [LHsDecl a] -> HsGroup a
--- The decls are imported, and should not have a splice
-addImpDecls group decls = case addl group decls of
-                               (group', Nothing) -> group'
-                               other             -> panic "addImpDecls"
+checkDecBrGroup :: [LHsDecl a] -> P (HsGroup a)
+-- Turn the body of a [d| ... |] into a HsGroup
+-- There should be no splices in the "..."
+checkDecBrGroup decls 
+  = case addl emptyRdrGroup decls of
+       (group, Nothing) -> return group
+       (_, Just (SpliceDecl (L loc _), _)) -> 
+               parseError loc "Declaration splices are not permitted inside declaration brackets"
+               -- Why not?  See Section 7.3 of the TH paper.  
 
 addl :: HsGroup a -> [LHsDecl a] -> (HsGroup a, Maybe (SpliceDecl a, [LHsDecl a]))
        -- This stuff reverses the declarations (again) but it doesn't matter
@@ -309,8 +310,6 @@ add gp@(HsGroup {hs_tyclds = ts, hs_fixds = fs})
        | isClassDecl d =       
                let fsigs = [ L l f | L l (FixSig f) <- tcdSigs d ] in
                addl (gp { hs_tyclds = L l d : ts, hs_fixds = fsigs ++ fs}) ds
-       | isFamInstDecl d = 
-               addl (gp { hs_tyclds = L l d : ts }) ds
        | otherwise =
                addl (gp { hs_tyclds = L l d : ts }) ds