import Module ( Module, mkModuleFS )
import Name ( Name, NamedThing(getName), nameModule, nameParent_maybe,
nameOccName, isExternalName, nameSrcLoc )
+import Maybes ( mapCatMaybes )
import SrcLoc ( isGoodSrcLoc, SrcSpan )
import Outputable
import Util ( thenCmp )
lookupGRE_RdrName :: RdrName -> GlobalRdrEnv -> [GlobalRdrElt]
lookupGRE_RdrName rdr_name env
- = case lookupOccEnv env occ of
- Nothing -> []
- Just gres | isUnqual rdr_name -> filter unQualOK gres
- | otherwise -> filter (hasQual mod) gres
- where
- mod = rdrNameModule rdr_name
- occ = rdrNameOcc rdr_name
+ = case lookupOccEnv env (rdrNameOcc rdr_name) of
+ Nothing -> []
+ Just gres -> pickGREs rdr_name gres
lookupGRE_Name :: GlobalRdrEnv -> Name -> [GlobalRdrElt]
lookupGRE_Name env name
gre_name gre == name ]
+pickGREs :: RdrName -> [GlobalRdrElt] -> [GlobalRdrElt]
+-- Take a list of GREs which have the right OccName
+-- Pick those GREs that are suitable for this RdrName
+-- And for those, keep only only the Provenances that are suitable
+--
+-- Consider
+-- module A ( f ) where
+-- import qualified Foo( f )
+-- import Baz( f )
+-- f = undefined
+-- Let's suppose that Foo.f and Baz.f are the same entity really.
+-- The export of f is ambiguous because it's in scope from the local def
+-- and the import. The lookup of (Unqual f) should return a GRE for
+-- the locally-defined f, and a GRE for the imported f, with a *single*
+-- provenance, namely the one for Baz(f).
+pickGREs rdr_name gres
+ = mapCatMaybes pick gres
+ where
+ is_unqual = isUnqual rdr_name
+ mod = rdrNameModule rdr_name
+
+ pick :: GlobalRdrElt -> Maybe GlobalRdrElt
+ pick gre@(GRE {gre_prov = LocalDef m}) -- Local def
+ | is_unqual || m == mod = Just gre
+ | otherwise = Nothing
+ pick gre@(GRE {gre_prov = Imported [is]}) -- Single import (efficiency)
+ | is_unqual && not (is_qual (is_decl is)) = Just gre
+ | mod == is_as (is_decl is) = Just gre
+ | otherwise = Nothing
+ pick gre@(GRE {gre_prov = Imported is}) -- Multiple import
+ | null filtered_is = Nothing
+ | otherwise = Just (gre {gre_prov = Imported filtered_is})
+ where
+ filtered_is | is_unqual = filter (not . is_qual . is_decl) is
+ | otherwise = filter ((== mod) . is_as . is_decl) is
+
isLocalGRE :: GlobalRdrElt -> Bool
isLocalGRE (GRE {gre_prov = LocalDef _}) = True
isLocalGRE other = False
unQualOK (GRE {gre_prov = LocalDef _}) = True
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_decl) is
-
plusGlobalRdrEnv :: GlobalRdrEnv -> GlobalRdrEnv -> GlobalRdrEnv
plusGlobalRdrEnv env1 env2 = plusOccEnv_C (foldr insertGRE) env1 env2
plusProv (Imported is1) (Imported is2) = Imported (is1++is2)
pprNameProvenance :: GlobalRdrElt -> SDoc
+-- Print out the place where the name was imported
pprNameProvenance (GRE {gre_name = name, gre_prov = LocalDef _})
= ptext SLIT("defined at") <+> ppr (nameSrcLoc name)
pprNameProvenance (GRE {gre_name = name, gre_prov = Imported (why:whys)})