[project @ 2002-10-09 15:16:53 by simonpj]

Dont complain about unused things bound by deriving clause

diff --git a/ghc/compiler/rename/RnNames.lhs b/ghc/compiler/rename/RnNames.lhs
index 3e440e9..f1c7992 100644 (file)
--- a/ghc/compiler/rename/RnNames.lhs
+++ b/ghc/compiler/rename/RnNames.lhs
@@ -29,7 +29,7 @@ import Module         ( Module, ModuleName, moduleName,
                          moduleNameUserString, 
                          unitModuleEnvByName, lookupModuleEnvByName,
                          moduleEnvElts )
-import Name            ( Name, nameSrcLoc, nameOccName, nameModule )
+import Name            ( Name, nameSrcLoc, nameOccName, nameModule, isExternalName )
 import NameSet
 import NameEnv
 import OccName         ( OccName, dataName, isTcOcc )
@@ -615,9 +615,15 @@ reportUnusedNames gbl_env used_names
     (defined_and_used, defined_but_not_used) = partition used defined_names
     used gre = gre_name gre `elemNameSet` really_used_names
     
-    -- Filter out the ones only defined implicitly
+    -- Filter out the ones that are 
+    --  (a) defined in this module, and
+    -- (b) not defined by a 'deriving' clause 
+    -- The latter have an Internal Name, so we can filter them out easily
     bad_locals :: [GlobalRdrElt]
-    bad_locals = filter isLocalGRE defined_but_not_used
+    bad_locals = filter is_bad defined_but_not_used
+
+    is_bad :: GlobalRdrElt -> Bool
+    is_bad gre = isLocalGRE gre && isExternalName (gre_name gre)
     
     bad_imports :: [GlobalRdrElt]
     bad_imports = filter bad_imp defined_but_not_used