[project @ 2005-05-19 11:15:40 by simonpj]

[ghc-hetmet.git] / ghc / compiler / basicTypes / RdrName.lhs

diff --git a/ghc/compiler/basicTypes/RdrName.lhs b/ghc/compiler/basicTypes/RdrName.lhs
index 9d2e416..8903b8a 100644 (file)
--- a/ghc/compiler/basicTypes/RdrName.lhs
+++ b/ghc/compiler/basicTypes/RdrName.lhs
@@ -32,9 +32,10 @@ module RdrName (
        lookupGRE_RdrName, lookupGRE_Name,
 
        -- GlobalRdrElt, Provenance, ImportSpec
-       GlobalRdrElt(..), Provenance(..), ImportSpec(..),
-       isLocalGRE, unQualOK,
-       pprNameProvenance
+       GlobalRdrElt(..), isLocalGRE, unQualOK, 
+       Provenance(..), pprNameProvenance,
+       ImportSpec(..), ImpDeclSpec(..), ImpItemSpec(..), 
+       importSpecLoc, importSpecModule
   ) where 
 
 #include "HsVersions.h"
@@ -373,12 +374,12 @@ isLocalGRE other                           = False
 unQualOK :: GlobalRdrElt -> Bool
 -- An unqualifed version of this thing is in scope
 unQualOK (GRE {gre_prov = LocalDef _})  = True
-unQualOK (GRE {gre_prov = Imported is}) = not (all is_qual is)
+unQualOK (GRE {gre_prov = Imported is}) = not (all (is_qual . is_decl) is)
 
 hasQual :: Module -> GlobalRdrElt -> Bool
 -- A qualified version of this thing is in scope
 hasQual mod (GRE {gre_prov = LocalDef m})  = m == mod
-hasQual mod (GRE {gre_prov = Imported is}) = any ((== mod) . is_as) is
+hasQual mod (GRE {gre_prov = Imported is}) = any ((== mod) . is_as . is_decl) is
 
 plusGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrEnv -> GlobalRdrEnv
 plusGlobalRdrEnv env1 env2 = plusOccEnv_C (foldr insertGRE) env1 env2
@@ -414,40 +415,52 @@ plusGRE g1 g2
 %************************************************************************
 
 The "provenance" of something says how it came to be in scope.
+It's quite elaborate so that we can give accurate unused-name warnings.
 
 \begin{code}
 data Provenance
   = LocalDef           -- Defined locally
        Module
 
-  | Imported           -- Imported
+  | Imported                           -- Imported
        [ImportSpec]    -- INVARIANT: non-empty
 
-data ImportSpec                -- Describes a particular import declaration
-                       -- Shared among all the Provenaces for a
-                       -- import-all declaration; otherwise it's done
-                       -- per explictly-named item
-  = ImportSpec {
+data ImportSpec = ImpSpec { is_decl :: ImpDeclSpec,
+                           is_item ::  ImpItemSpec }
+               deriving( Eq, Ord )
+
+data ImpDeclSpec       -- Describes a particular import declaration
+                       -- Shared among all the Provenaces for that decl
+  = ImpDeclSpec {
        is_mod      :: Module,  -- 'import Muggle'
                                -- Note the Muggle may well not be 
                                -- the defining module for this thing!
        is_as       :: Module,  -- 'as M' (or 'Muggle' if there is no 'as' clause)
        is_qual     :: Bool,    -- True <=> qualified (only)
-       is_explicit :: Bool,    -- True <=> explicit import (see below)
-       is_loc      :: SrcSpan  -- Location of import item
+       is_dloc     :: SrcSpan  -- Location of import declaration
+    }
+
+data ImpItemSpec  -- Describes import info a particular Name
+  = ImpAll             -- The import had no import list, 
+                       -- or  had a hiding list
+
+  | ImpSome {          -- The import had an import list
+       is_explicit :: Bool,
+       is_iloc     :: SrcSpan  -- Location of the import item
     }
        -- The is_explicit field is True iff the thing was named 
        -- *explicitly* in the import specs rather 
-       -- than being imported as part of a group 
-       -- e.g.         import B
-       --              import C( T(..) )
-       -- Here, everything imported by B, and the constructors of T
-       -- are not named explicitly; only T is named explicitly.
-       -- This info is used when warning of unused names.
-       --
-       -- We keep ImportSpec separate from the Bool so that the
-       -- former can be shared between all Provenances for a particular
-       -- import declaration.  
+       -- than being imported as part of a "..." group 
+       -- e.g.         import C( T(..) )
+       -- Here the constructors of T are not named explicitly; 
+       -- only T is named explicitly.
+
+importSpecLoc :: ImportSpec -> SrcSpan
+importSpecLoc (ImpSpec decl ImpAll) = is_dloc decl
+importSpecLoc (ImpSpec _    item)   = is_iloc item
+
+importSpecModule :: ImportSpec -> Module
+importSpecModule is = is_mod (is_decl is)
 
 -- Note [Comparing provenance]
 -- Comparison of provenance is just used for grouping 
@@ -455,7 +468,10 @@ data ImportSpec            -- Describes a particular import declaration
 instance Eq Provenance where
   p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
 
-instance Eq ImportSpec where
+instance Eq ImpDeclSpec where
+  p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
+
+instance Eq ImpItemSpec where
   p1 == p2 = case p1 `compare` p2 of EQ -> True; _ -> False
 
 instance Ord Provenance where
@@ -465,9 +481,12 @@ instance Ord Provenance where
    compare (Imported is1) (Imported is2) = compare (head is1) 
        {- See Note [Comparing provenance] -}      (head is2)
 
-instance Ord ImportSpec where
+instance Ord ImpDeclSpec where
    compare is1 is2 = (is_mod is1 `compare` is_mod is2) `thenCmp` 
-                    (is_loc is1 `compare` is_loc is2)
+                    (is_dloc is1 `compare` is_dloc is2)
+
+instance Ord ImpItemSpec where
+   compare is1 is2 = is_iloc is1 `compare` is_iloc is2
 \end{code}
 
 \begin{code}
@@ -495,7 +514,7 @@ ppr_defn loc | isGoodSrcLoc loc = parens (ptext SLIT("defined at") <+> ppr loc)
             | otherwise        = empty
 
 instance Outputable ImportSpec where
-   ppr imp_spec
-     = ptext SLIT("imported from") <+> ppr (is_mod imp_spec) 
-       <+> ptext SLIT("at") <+> ppr (is_loc imp_spec)
+   ppr imp_spec@(ImpSpec imp_decl _)
+     = ptext SLIT("imported from") <+> ppr (is_mod imp_decl) 
+       <+> ptext SLIT("at") <+> ppr (importSpecLoc imp_spec)
 \end{code}