Major patch to fix reporting of unused imports

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

diff --git a/compiler/rename/RnEnv.lhs b/compiler/rename/RnEnv.lhs
index 888ac28..2ecaf61 100644 (file)
--- a/compiler/rename/RnEnv.lhs
+++ b/compiler/rename/RnEnv.lhs
@@ -15,7 +15,7 @@ module RnEnv (
        lookupInstDeclBndr, lookupRecordBndr, lookupConstructorFields,
        lookupSyntaxName, lookupSyntaxTable, 
        lookupGreRn, lookupGreLocalRn, lookupGreRn_maybe,
-       getLookupOccRn,
+       getLookupOccRn, addUsedRdrNames,
 
        newLocalsRn, newIPNameRn,
        bindLocalNames, bindLocalNamesFV, 
@@ -68,6 +68,7 @@ import List           ( nubBy )
 import DynFlags
 import FastString
 import Control.Monad
+import qualified Data.Set as Set
 \end{code}
 
 \begin{code}
@@ -307,6 +308,7 @@ lookup_sub_bndr :: (GlobalRdrElt -> Bool) -> SDoc -> RdrName -> RnM Name
 lookup_sub_bndr is_good doc rdr_name
   | isUnqual rdr_name  -- Find all the things the rdr-name maps to
   = do {               -- and pick the one with the right parent name
+        ; addUsedRdrName rdr_name
        ; env <- getGlobalRdrEnv
        ; case filter is_good (lookupGlobalRdrEnv env (rdrNameOcc rdr_name)) of
                -- NB: lookupGlobalRdrEnv, not lookupGRE_RdrName!
@@ -328,22 +330,18 @@ lookup_sub_bndr is_good doc rdr_name
 newIPNameRn :: IPName RdrName -> TcRnIf m n (IPName Name)
 newIPNameRn ip_rdr = newIPName (mapIPName rdrNameOcc ip_rdr)
 
--- Looking up family names in type instances is a subtle affair.  The family
--- may be imported, in which case we need to lookup the occurence of a global
--- name.  Alternatively, the family may be in the same binding group (and in
--- fact in a declaration processed later), and we need to create a new top
--- source binder.
+-- If the family is declared locally, it will not yet be in the main
+-- environment; hence, we pass in an extra one here, which we check first.
+-- See "Note [Looking up family names in family instances]" in 'RnNames'.
 --
--- So, also this is strictly speaking an occurence, we cannot raise an error
--- message yet for instances without a family declaration.  This will happen
--- during renaming the type instance declaration in RnSource.rnTyClDecl.
---
-lookupFamInstDeclBndr :: Module -> Located RdrName -> RnM Name
-lookupFamInstDeclBndr mod lrdr_name@(L _ rdr_name)
-  = do { mb_gre <- lookupGreRn_maybe rdr_name
-       ; case mb_gre of
-           Just gre -> returnM (gre_name gre)
-          Nothing  -> newTopSrcBinder mod lrdr_name }
+lookupFamInstDeclBndr :: GlobalRdrEnv -> Located RdrName -> RnM Name
+lookupFamInstDeclBndr tyclGroupEnv (L loc rdr_name)
+  = setSrcSpan loc $
+      case lookupGRE_RdrName rdr_name tyclGroupEnv of
+        (gre:_) -> return $ gre_name gre
+          -- if there is more than one, an error will be raised elsewhere
+        []      -> lookupOccRn rdr_name
+
 
 --------------------------------------------------
 --             Occurrences
@@ -424,7 +422,27 @@ unboundName rdr_name
 lookupGreRn_maybe :: RdrName -> RnM (Maybe GlobalRdrElt)
 -- Just look up the RdrName in the GlobalRdrEnv
 lookupGreRn_maybe rdr_name 
-  = lookupGreRn_help rdr_name (lookupGRE_RdrName rdr_name)
+  = do { mGre <- lookupGreRn_help rdr_name (lookupGRE_RdrName rdr_name)
+       ; case mGre of
+           Just gre ->
+               case gre_prov gre of
+               LocalDef   -> return ()
+               Imported _ -> addUsedRdrName rdr_name
+           Nothing ->
+               return ()
+       ; return mGre }
+
+addUsedRdrName :: RdrName -> RnM ()
+addUsedRdrName rdr
+  = do { env <- getGblEnv
+       ; updMutVar (tcg_used_rdrnames env)
+                  (\s -> Set.insert rdr s) }
+
+addUsedRdrNames :: [RdrName] -> RnM ()
+addUsedRdrNames rdrs
+  = do { env <- getGblEnv
+       ; updMutVar (tcg_used_rdrnames env)
+                  (\s -> foldr Set.insert s rdrs) }
 
 lookupGreRn :: RdrName -> RnM GlobalRdrElt
 -- If not found, add error message, and return a fake GRE