[project @ 1999-01-14 17:58:41 by sof]

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

diff --git a/ghc/compiler/rename/RnEnv.lhs b/ghc/compiler/rename/RnEnv.lhs
index 30f5f19..066c991 100644 (file)
--- a/ghc/compiler/rename/RnEnv.lhs
+++ b/ghc/compiler/rename/RnEnv.lhs
@@ -21,7 +21,7 @@ import Name           ( Name, Provenance(..), ExportFlag(..), NamedThing(..),
                          ImportReason(..), getSrcLoc, 
                          mkLocalName, mkGlobalName, 
                          nameOccName, 
-                         pprOccName, isLocalName, isLocallyDefined, 
+                         pprOccName, isLocalName, isLocallyDefined, isAnonOcc,
                          setNameProvenance, getNameProvenance, pprNameProvenance
                        )
 import NameSet
@@ -169,6 +169,7 @@ newLocalNames rdr_names
        n          = length rdr_names
        (us', us1) = splitUniqSupply us
        uniqs      = uniqsFromSupply n us1
+         -- Note: we're not making use of the source location. Not good.
        locals     = [ mkLocalName uniq (rdrNameOcc rdr_name)
                     | ((rdr_name,loc), uniq) <- rdr_names `zip` uniqs
                     ]
@@ -680,8 +681,8 @@ warnUnusedTopNames ns
   = returnRn ()        -- Don't force ns unless necessary
 
 warnUnusedTopNames (n:ns)
-  | is_local     && opt_WarnUnusedBinds   = warnUnusedNames ns
-  | not is_local && opt_WarnUnusedImports = warnUnusedNames ns
+  | is_local     && opt_WarnUnusedBinds   = warnUnusedNames False{-include name's provenance-} ns
+  | not is_local && opt_WarnUnusedImports = warnUnusedNames False ns
   where
     is_local = isLocallyDefined n
 
@@ -689,23 +690,35 @@ warnUnusedTopName other = returnRn ()
 
 warnUnusedBinds ns
   | not opt_WarnUnusedBinds = returnRn ()
-  | otherwise              = warnUnusedNames ns
+  | otherwise              = warnUnusedNames False ns
 
+{-
+ Haskell 98 encourages compilers to suppress warnings about
+ unused names in a pattern if they start with "_". Which
+ we do here.
+
+ Note: omit the inclusion of the names' provenance in the
+ generated warning -- it's already given in the header
+ of the warning (+ the local names we've been given have
+ a provenance that's ultra low in content.)
+
+-}
 warnUnusedMatches names
-  | opt_WarnUnusedMatches = warnUnusedNames names
+  | opt_WarnUnusedMatches = warnUnusedNames True (filter (not.isAnonOcc.getOccName) names)
   | otherwise            = returnRn ()
 
-warnUnusedNames :: [Name] -> RnM s d ()
-warnUnusedNames []
+warnUnusedNames :: Bool{-display provenance-} -> [Name] -> RnM s d ()
+warnUnusedNames _ []
   = returnRn ()
 
-warnUnusedNames names 
+warnUnusedNames short_msg names 
   = addWarnRn $
     sep [text "The following names are unused:",
-        nest 4 (vcat (map pp names))]
+        nest 4 ((if short_msg then hsep else vcat) (map pp names))]
   where
-    pp n = ppr n <> comma <+> pprNameProvenance n
-
+    pp n 
+     | short_msg = ppr n
+     | otherwise = ppr n <> comma <+> pprNameProvenance n
 
 addNameClashErrRn rdr_name names
 {-     NO LONGER NEEDED WITH LAZY NAME-CLASH REPORTING