Improve error reporting for type signatures

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

diff --git a/compiler/rename/RnEnv.lhs b/compiler/rename/RnEnv.lhs
index 32806f0..54a768a 100644 (file)
--- a/compiler/rename/RnEnv.lhs
+++ b/compiler/rename/RnEnv.lhs
@@ -15,6 +15,7 @@ module RnEnv (
        lookupLocatedInstDeclBndr,
        lookupSyntaxName, lookupSyntaxTable, lookupImportedName,
        lookupGreRn, lookupGreRn_maybe,
+       getLookupOccRn,
 
        newLocalsRn, newIPNameRn,
        bindLocalNames, bindLocalNamesFV,
@@ -194,8 +195,25 @@ lookupTopBndrRn rdr_name
 -- The Haskell98 report does not stipulate this, but it will!
 -- So we must treat the 'f' in the signature in the same way
 -- as the binding occurrence of 'f', using lookupBndrRn
+--
+-- However, consider this case:
+--     import M( f )
+--     f :: Int -> Int
+--     g x = x
+-- We don't want to say 'f' is out of scope; instead, we want to
+-- return the imported 'f', so that later on the reanamer will
+-- correctly report "misplaced type sig".
 lookupLocatedSigOccRn :: Located RdrName -> RnM (Located Name)
-lookupLocatedSigOccRn = lookupLocatedBndrRn
+lookupLocatedSigOccRn = wrapLocM $ \ rdr_name -> do
+       { local_env <- getLocalRdrEnv
+       ; case lookupLocalRdrEnv local_env rdr_name of {
+               Just n  -> return n ;
+               Nothing -> do
+       { mb_gre <- lookupGreLocalRn rdr_name
+       ; case mb_gre of 
+               Just gre -> return (gre_name gre) 
+               Nothing  -> lookupGlobalOccRn rdr_name
+       }}}
 
 -- lookupInstDeclBndr is used for the binders in an 
 -- instance declaration.   Here we use the class name to
@@ -255,6 +273,11 @@ lookupFamInstDeclBndr mod lrdr_name@(L _ rdr_name)
 --             Occurrences
 --------------------------------------------------
 
+getLookupOccRn :: RnM (Name -> Maybe Name)
+getLookupOccRn
+  = getLocalRdrEnv                     `thenM` \ local_env ->
+    return (lookupLocalRdrEnv local_env . mkRdrUnqual . nameOccName)
+
 lookupLocatedOccRn :: Located RdrName -> RnM (Located Name)
 lookupLocatedOccRn = wrapLocM lookupOccRn
 
@@ -546,7 +569,7 @@ At the moment this just happens for
   * "do" notation
 
 We store the relevant Name in the HsSyn tree, in 
-  * HsIntegral/HsFractional    
+  * HsIntegral/HsFractional/HsIsString
   * NegApp
   * NPlusKPat
   * HsDo