[project @ 1998-05-01 16:26:11 by simonpj]

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

diff --git a/ghc/compiler/rename/RnNames.lhs b/ghc/compiler/rename/RnNames.lhs
index 25d28e0..a45926d 100644 (file)
--- a/ghc/compiler/rename/RnNames.lhs
+++ b/ghc/compiler/rename/RnNames.lhs
@@ -281,12 +281,23 @@ filterImports mod (Just (want_hiding, import_items)) avails
       = addErrRn (badImportItemErr mod item)   `thenRn_`
        returnRn NotAvailable
 
-      | otherwise   = returnRn filtered_avail
+      | dodgy_import = addWarnRn (dodgyImportWarn mod item)    `thenRn_`
+                      returnRn filtered_avail
+
+      | otherwise    = returnRn filtered_avail
                
       where
        maybe_in_import_avails = lookupFM import_fm (ieOcc item)
        Just avail             = maybe_in_import_avails
        filtered_avail         = filterAvail item avail
+       dodgy_import           = case (item, avail) of
+                                  (IEThingAll _, AvailTC _ [n]) -> True
+                                       -- This occurs when you import T(..), but
+                                       -- only export T abstractly.  The single [n]
+                                       -- in the AvailTC is the type or class itself
+                                       
+                                  other -> False
+                                       
 \end{code}
 
 
@@ -604,6 +615,11 @@ badImportItemErr mod ie
   = sep [ptext SLIT("Module"), quotes (pprModule mod), 
         ptext SLIT("does not export"), quotes (ppr ie)]
 
+dodgyImportWarn mod (IEThingAll tc)
+  = sep [ptext SLIT("Module") <+> quotes (pprModule mod) <+> ptext SLIT("exports") <+> quotes (ppr tc), 
+        ptext SLIT("with no constructors/class operations;"),
+        ptext SLIT("yet it is imported with a (..)")]
+
 modExportErr mod
   = hsep [ ptext SLIT("Unknown module in export list: module"), quotes (pprModule mod)]