+mkModuleMap
+ :: PackageConfigMap
+ -> [PackageId]
+ -> ModuleEnv [(PackageConfig, Bool)]
+mkModuleMap pkg_db pkgs = foldr extend_modmap emptyUFM pkgs
+ where
+ extend_modmap pkgname modmap =
+ addListToUFM_C (++) modmap
+ [(m, [(pkg, m `elem` exposed_mods)]) | m <- all_mods]
+ where
+ pkg = expectJust "mkModuleMap" (lookupPackage pkg_db pkgname)
+ exposed_mods = map mkModule (exposedModules pkg)
+ hidden_mods = map mkModule (hiddenModules pkg)
+ all_mods = exposed_mods ++ hidden_mods
+
+-- -----------------------------------------------------------------------------
+-- Check for conflicts in the program.
+
+-- | A conflict arises if the program contains two modules with the same
+-- name, which can arise if the program depends on multiple packages that
+-- expose the same module, or if the program depends on a package that
+-- contains a module also present in the program (the "home package").
+--
+checkForPackageConflicts
+ :: DynFlags
+ -> [Module] -- modules in the home package
+ -> [PackageId] -- packages on which the program depends
+ -> MaybeErr Message ()
+
+checkForPackageConflicts dflags mods pkgs = do
+ let
+ state = pkgState dflags
+ pkg_db = pkgIdMap state
+ --
+ dep_pkgs <- closeDepsErr pkg_db pkgs
+
+ let
+ extend_modmap pkgname modmap =
+ addListToFM_C (++) modmap
+ [(m, [(pkg, m `elem` exposed_mods)]) | m <- all_mods]
+ where
+ pkg = expectJust "checkForPackageConflicts"
+ (lookupPackage pkg_db pkgname)
+ exposed_mods = map mkModule (exposedModules pkg)
+ hidden_mods = map mkModule (hiddenModules pkg)
+ all_mods = exposed_mods ++ hidden_mods
+
+ mod_map = foldr extend_modmap emptyFM pkgs
+ mod_map_list :: [(Module,[(PackageConfig,Bool)])]
+ mod_map_list = fmToList mod_map
+
+ overlaps = [ (m, map fst ps) | (m,ps@(_:_:_)) <- mod_map_list ]
+ --
+ if not (null overlaps)
+ then Failed (pkgOverlapError overlaps)
+ else do
+
+ let
+ overlap_mods = [ (mod,pkg)
+ | mod <- mods,
+ Just ((pkg,_):_) <- [lookupFM mod_map mod] ]
+ -- will be only one package here
+ if not (null overlap_mods)
+ then Failed (modOverlapError overlap_mods)
+ else do
+
+ return ()
+
+pkgOverlapError overlaps = vcat (map msg overlaps)
+ where
+ msg (mod,pkgs) =
+ text "conflict: module" <+> quotes (ppr mod)
+ <+> ptext SLIT("is present in multiple packages:")
+ <+> hsep (punctuate comma (map pprPkg pkgs))
+
+modOverlapError overlaps = vcat (map msg overlaps)