Handle re-exported modules when constructing ExportsMap (#2468)

* Handle re-exported modules when constructing ExportsMap

* Remove unused import, use let

Co-authored-by: Pepe Iborra <[email protected]>

Author: jhrcek

ghcide/src/Development/IDE/Types/HscEnvEq.hs

@@ -16,7 +16,6 @@ import           Control.Concurrent.Strict       (modifyVar, newVar)
 import           Control.DeepSeq                 (force)
 import           Control.Exception               (evaluate, mask, throwIO)
 import           Control.Monad.Extra             (eitherM, join, mapMaybeM)
-import           Control.Monad.IO.Class
 import           Data.Either                     (fromRight)
 import           Data.Set                        (Set)
 import qualified Data.Set                        as Set
@@ -76,22 +75,25 @@ newHscEnvEqWithImportPaths envImportPaths hscEnv deps = do
         -- compute the package imports
         let pkgst   = unitState hscEnv
             depends = explicitUnits pkgst
-            targets =
-                [ (pkg, mn)
+            modules =
+                [ m
                 | d        <- depends
                 , Just pkg <- [lookupPackageConfig d hscEnv]
-                , (mn, _)  <- unitExposedModules pkg
+                , (modName, maybeOtherPkgMod) <- unitExposedModules pkg
+                , let m = case maybeOtherPkgMod of
+                        -- When module is re-exported from another package,
+                        -- the origin module is represented by value in Just
+                        Just otherPkgMod -> otherPkgMod
+                        Nothing -> mkModule (unitInfoId pkg) modName
                 ]
 
-            doOne (pkg, mn) = do
-                modIface <- liftIO $ initIfaceLoad hscEnv $ loadInterface
-                    ""
-                    (mkModule (unitInfoId pkg) mn)
-                    (ImportByUser NotBoot)
+            doOne m = do
+                modIface <- initIfaceLoad hscEnv $
+                    loadInterface "" m (ImportByUser NotBoot)
                 return $ case modIface of
                     Maybes.Failed    _r -> Nothing
                     Maybes.Succeeded mi -> Just mi
-        modIfaces <- mapMaybeM doOne targets
+        modIfaces <- mapMaybeM doOne modules
         return $ createExportsMap modIfaces
 
     -- similar to envPackageExports, evaluated lazily