[project @ 2000-07-18 14:50:32 by simonpj]

Arrange that type signatures that have no "parent" signatures
work right.  For example

	   module A
	      f :: Int -> Int

The panic in RnEnv.lookupBndrRn becomes an error message.  Also
RnBinds.rnTopMonoBinds and rnMonoBinds were wrongly ignoring all
signatures altogether if there were no bindings!

diff --git a/ghc/compiler/rename/RnBinds.lhs b/ghc/compiler/rename/RnBinds.lhs
index ef5596b..c3c31c0 100644 (file)
--- a/ghc/compiler/rename/RnBinds.lhs
+++ b/ghc/compiler/rename/RnBinds.lhs
@@ -165,9 +165,6 @@ rnTopBinds (MonoBind bind sigs _)     = rnTopMonoBinds bind sigs
   -- The parser doesn't produce other forms
 
 
-rnTopMonoBinds EmptyMonoBinds sigs 
-  = returnRn (EmptyBinds, emptyFVs)
-
 rnTopMonoBinds mbinds sigs
  =  mapRn lookupBndrRn binder_rdr_names                `thenRn` \ binder_names ->
     let
@@ -218,8 +215,6 @@ rnMonoBinds :: RdrNameMonoBinds
            -> (RenamedHsBinds -> RnMS (result, FreeVars))
            -> RnMS (result, FreeVars)
 
-rnMonoBinds EmptyMonoBinds sigs thing_inside = thing_inside EmptyBinds
-
 rnMonoBinds mbinds sigs        thing_inside -- Non-empty monobinds
   =    -- Extract all the binders in this group,
        -- and extend current scope, inventing new names for the new binders
@@ -284,7 +279,7 @@ rn_mono_binds siglist mbinds
     let 
         edges      = mkEdges (mbinds_info `zip` [(0::Int)..])
        scc_result  = stronglyConnComp edges
-       final_binds = foldr1 ThenBinds (map reconstructCycle scc_result)
+       final_binds = foldr (ThenBinds . reconstructCycle) EmptyBinds scc_result
 
         -- Deal with bound and free-var calculation
        rhs_fvs = plusFVs [fvs | (_,fvs,_,_) <- mbinds_info]

diff --git a/ghc/compiler/rename/RnEnv.lhs b/ghc/compiler/rename/RnEnv.lhs
index 15a46bf..80b6174 100644 (file)
--- a/ghc/compiler/rename/RnEnv.lhs
+++ b/ghc/compiler/rename/RnEnv.lhs
@@ -452,7 +452,14 @@ lookupBndrRn rdr_name
                case lookupRdrEnv global_env (qualifyRdrName mod rdr_name) of
                  Just (name:rest) -> ASSERT( null rest )
                                      returnRn name 
-                 Nothing          -> pprPanic "lookupBndrRn" (ppr mod <+> ppr rdr_name)
+                 Nothing          ->   -- Almost always this case is a compiler bug.
+                                       -- But consider a type signature that doesn't have 
+                                       -- a corresponding binder: 
+                                       --      module M where { f :: Int->Int }
+                                       -- We use lookupSigOccRn, which uses lookupBndrRn (for good reasons)
+                                       -- and we don't want to panic.  So we report an out-of-scope error
+                                       failWithRn (mkUnboundName rdr_name)
+                                                  (unknownNameErr rdr_name)
     }
 
 -- lookupOccRn looks up an occurrence of a RdrName