Fix multi unit session when some packages have reexported modules.

ghcide/session-loader/Development/IDE/Session.hs

@@ -121,8 +121,7 @@ import           Development.IDE.GHC.Compat.CmdLine
 import qualified Data.Set                             as OS
 
 import           GHC.Data.Bag
-import           GHC.Driver.Env                       (hscSetActiveUnitId,
-                                                       hsc_all_home_unit_ids)
+import           GHC.Driver.Env                       (hsc_all_home_unit_ids)
 import           GHC.Driver.Errors.Types
 import           GHC.Driver.Make                      (checkHomeUnitsClosed)
 import           GHC.Types.Error                      (errMsgDiagnostic)

ghcide/src/Development/IDE/GHC/Compat/Env.hs

@@ -57,6 +57,8 @@ module Development.IDE.GHC.Compat.Env (
     Development.IDE.GHC.Compat.Env.platformDefaultBackend,
     workingDirectory,
     setWorkingDirectory,
+    hscSetActiveUnitId,
+    reexportedModules,
     ) where
 
 import           GHC                 (setInteractiveDynFlags)
@@ -78,10 +80,20 @@ import           GHC.Utils.TmpFs
 
 #if !MIN_VERSION_ghc(9,3,0)
 import           GHC.Driver.Env      (HscEnv, hsc_EPS)
+import qualified Data.Set            as S
 #endif
 
 #if MIN_VERSION_ghc(9,3,0)
-import           GHC.Driver.Env      (HscEnv)
+import           GHC.Driver.Env      (HscEnv, hscSetActiveUnitId)
+#endif
+
+
+#if !MIN_VERSION_ghc(9,3,0)
+hscSetActiveUnitId :: UnitId -> HscEnv -> HscEnv
+hscSetActiveUnitId _ env = env
+
+reexportedModules :: HscEnv -> S.Set a
+reexportedModules _ = S.empty
 #endif
 
 #if MIN_VERSION_ghc(9,3,0)

ghcide/src/Development/IDE/Import/FindImports.hs

@@ -23,7 +23,8 @@ import           Development.IDE.Types.Location
 -- standard imports
 import           Control.Monad.Extra
 import           Control.Monad.IO.Class
-import           Data.List                         (isSuffixOf)
+import           Data.List                         (isSuffixOf, find)
+import qualified Data.Set                          as S
 import           Data.Maybe
 import           System.FilePath
 
@@ -70,19 +71,30 @@ modSummaryToArtifactsLocation nfp ms = ArtifactsLocation nfp (ms_location <$> ms
       Just modSum -> isSource (ms_hsc_src modSum)
     mbMod = ms_mod <$> ms
 
+data LocateResult
+  = LocateNotFound
+  | LocateFoundReexport UnitId
+  | LocateFoundFile UnitId NormalizedFilePath
+
 -- | locate a module in the file system. Where we go from *daml to Haskell
 locateModuleFile :: MonadIO m
-             => [(UnitId, [FilePath])]
+             => [(UnitId, [FilePath], S.Set ModuleName)]
              -> [String]
              -> (ModuleName -> NormalizedFilePath -> m (Maybe NormalizedFilePath))
              -> Bool
              -> ModuleName
-             -> m (Maybe (UnitId, NormalizedFilePath))
+             -> m LocateResult
 locateModuleFile import_dirss exts targetFor isSource modName = do
   let candidates import_dirs =
         [ toNormalizedFilePath' (prefix </> moduleNameSlashes modName <.> maybeBoot ext)
            | prefix <- import_dirs , ext <- exts]
-  firstJustM go (concat [map (uid,) (candidates dirs) | (uid, dirs) <- import_dirss])
+  mf <- firstJustM go (concat [map (uid,) (candidates dirs) | (uid, dirs, _) <- import_dirss])
+  case mf of
+    Nothing ->
+      case find (\(_ , _, reexports) -> S.member modName reexports) import_dirss of
+        Just (uid,_,_) -> pure $ LocateFoundReexport uid
+        Nothing -> pure $ LocateNotFound
+    Just (uid,file) -> pure $ LocateFoundFile uid file
   where
     go (uid, candidate) = fmap ((uid,) <$>) $ targetFor modName candidate
     maybeBoot ext
@@ -94,11 +106,11 @@ locateModuleFile import_dirss exts targetFor isSource modName = do
 -- current module. In particular, it will return Nothing for 'main' components
 -- as they can never be imported into another package.
 #if MIN_VERSION_ghc(9,3,0)
-mkImportDirs :: HscEnv -> (UnitId, DynFlags) -> Maybe (UnitId, [FilePath])
-mkImportDirs _env (i, flags) = Just (i, importPaths flags)
+mkImportDirs :: HscEnv -> (UnitId, DynFlags) -> Maybe (UnitId, ([FilePath], S.Set ModuleName))
+mkImportDirs _env (i, flags) = Just (i, (importPaths flags, reexportedModules flags))
 #else
-mkImportDirs :: HscEnv -> (UnitId, DynFlags) -> Maybe (PackageName, (UnitId, [FilePath]))
-mkImportDirs env (i, flags) = (, (i, importPaths flags)) <$> getUnitName env i
+mkImportDirs :: HscEnv -> (UnitId, DynFlags) -> Maybe (PackageName, (UnitId, [FilePath], S.Set ModuleName))
+mkImportDirs env (i, flags) = (, (i, importPaths flags, S.empty)) <$> getUnitName env i
 #endif
 
 -- | locate a module in either the file system or the package database. Where we go from *daml to
@@ -125,16 +137,16 @@ locateModule env comp_info exts targetFor modName mbPkgName isSource = do
 #else
     Just "this" -> do
 #endif
-      lookupLocal (homeUnitId_ dflags) (importPaths dflags)
+      lookupLocal (homeUnitId_ dflags) (importPaths dflags) S.empty
     -- if a package name is given we only go look for a package
 #if MIN_VERSION_ghc(9,3,0)
     OtherPkg uid
-      | Just dirs <- lookup uid import_paths
-          -> lookupLocal uid dirs
+      | Just (dirs, reexports) <- lookup uid import_paths
+          -> lookupLocal uid dirs reexports
 #else
     Just pkgName
-      | Just (uid, dirs) <- lookup (PackageName pkgName) import_paths
-          -> lookupLocal uid dirs
+      | Just (uid, dirs, reexports) <- lookup (PackageName pkgName) import_paths
+          -> lookupLocal uid dirs reexports
 #endif
       | otherwise -> lookupInPackageDB
 #if MIN_VERSION_ghc(9,3,0)
@@ -143,10 +155,15 @@ locateModule env comp_info exts targetFor modName mbPkgName isSource = do
     Nothing -> do
 #endif
 
-      mbFile <- locateModuleFile ((homeUnitId_ dflags, importPaths dflags) : other_imports) exts targetFor isSource $ unLoc modName
+      -- Reexports for current unit have to be empty because they only apply to other units depending on the
+      -- current unit. If we set the reexports to be the actual reexports then we risk looping forever trying
+      -- to find the module from the perspective of the current unit.
+      mbFile <- locateModuleFile ((homeUnitId_ dflags, importPaths dflags, S.empty) : other_imports) exts targetFor isSource $ unLoc modName
       case mbFile of
-        Nothing          -> lookupInPackageDB
-        Just (uid, file) -> toModLocation uid file
+        LocateNotFound -> lookupInPackageDB
+        -- Lookup again with the perspective of the unit reexporting the file
+        LocateFoundReexport uid -> locateModule (hscSetActiveUnitId uid env) comp_info exts targetFor modName noPkgQual isSource
+        LocateFoundFile uid file -> toModLocation uid file
   where
     dflags = hsc_dflags env
     import_paths = mapMaybe (mkImportDirs env) comp_info
@@ -160,7 +177,7 @@ locateModule env comp_info exts targetFor modName mbPkgName isSource = do
       -- about which module unit a imports.
       -- Without multi-component support it is hard to recontruct the dependency environment so
       -- unit a will have both unit b and unit c in scope.
-      map (\uid -> (uid, importPaths (homeUnitEnv_dflags (ue_findHomeUnitEnv uid ue)))) hpt_deps
+      map (\uid -> let this_df = homeUnitEnv_dflags (ue_findHomeUnitEnv uid ue) in (uid, importPaths this_df, reexportedModules this_df)) hpt_deps
     ue = hsc_unit_env env
     units = homeUnitEnv_units $ ue_findHomeUnitEnv (homeUnitId_ dflags) ue
     hpt_deps :: [UnitId]
@@ -186,11 +203,13 @@ locateModule env comp_info exts targetFor modName mbPkgName isSource = do
         let genMod = mkModule (RealUnit $ Definite uid) (unLoc modName)  -- TODO support backpack holes
         return $ Right $ FileImport $ ArtifactsLocation file (Just loc) (not isSource) (Just genMod)
 
-    lookupLocal uid dirs = do
-      mbFile <- locateModuleFile [(uid, dirs)] exts targetFor isSource $ unLoc modName
+    lookupLocal uid dirs reexports = do
+      mbFile <- locateModuleFile [(uid, dirs, reexports)] exts targetFor isSource $ unLoc modName
       case mbFile of
-        Nothing   -> return $ Left $ notFoundErr env modName $ LookupNotFound []
-        Just (uid', file) -> toModLocation uid' file
+        LocateNotFound -> return $ Left $ notFoundErr env modName $ LookupNotFound []
+        -- Lookup again with the perspective of the unit reexporting the file
+        LocateFoundReexport uid' -> locateModule (hscSetActiveUnitId uid' env) comp_info exts targetFor modName noPkgQual isSource
+        LocateFoundFile uid' file -> toModLocation uid' file
 
     lookupInPackageDB = do
       case Compat.lookupModuleWithSuggestions env (unLoc modName) mbPkgName of
@@ -239,3 +258,11 @@ notFound = NotFound
   , fr_unusables = []
   , fr_suggestions = []
   }
+
+#if MIN_VERSION_ghc(9,3,0)
+noPkgQual :: PkgQual
+noPkgQual = NoPkgQual
+#else
+noPkgQual :: Maybe a
+noPkgQual = Nothing
+#endif

ghcide/test/data/multi-unit-reexport/a-1.0.0-inplace

@@ -0,0 +1,18 @@
+-this-package-name
+a
+-working-dir
+a
+-fbuilding-cabal-package
+-O0
+-i.
+-this-unit-id
+a-1.0.0-inplace
+-hide-all-packages
+-Wmissing-home-modules
+-no-user-package-db
+-package
+base
+-package
+text
+-XHaskell98
+A

ghcide/test/data/multi-unit-reexport/a/A.hs

@@ -0,0 +1,3 @@
+module A(foo) where
+import Data.Text
+foo = ()

ghcide/test/data/multi-unit-reexport/b-1.0.0-inplace

@@ -0,0 +1,21 @@
+-this-package-name
+b
+-working-dir
+b
+-fbuilding-cabal-package
+-O0
+-i
+-i.
+-this-unit-id
+b-1.0.0-inplace
+-hide-all-packages
+-Wmissing-home-modules
+-no-user-package-db
+-package-id
+a-1.0.0-inplace
+-reexported-module
+A
+-package
+base
+-XHaskell98
+B

ghcide/test/data/multi-unit-reexport/b/B.hs

@@ -0,0 +1,3 @@
+module B(module B) where
+import A
+qux = foo

ghcide/test/data/multi-unit-reexport/c-1.0.0-inplace

@@ -0,0 +1,19 @@
+-this-package-name
+c
+-working-dir
+c
+-fbuilding-cabal-package
+-O0
+-i
+-i.
+-this-unit-id
+c-1.0.0-inplace
+-hide-all-packages
+-Wmissing-home-modules
+-no-user-package-db
+-package-id
+b-1.0.0-inplace
+-package
+base
+-XHaskell98
+C

ghcide/test/data/multi-unit-reexport/c/C.hs

@@ -0,0 +1,4 @@
+module C(module C) where
+import A
+import B
+cux = foo `seq` qux

ghcide/test/data/multi-unit-reexport/cabal.project

@@ -0,0 +1,2 @@
+packages: a b c
+multi-repl: True

ghcide/test/data/multi-unit-reexport/hie.yaml

@@ -0,0 +1,6 @@
+cradle:
+  direct:
+    arguments: ["-unit" ,"@a-1.0.0-inplace"
+               ,"-unit" ,"@b-1.0.0-inplace" 
+               ,"-unit" ,"@c-1.0.0-inplace"
+               ]

ghcide/test/exe/CradleTests.hs

@@ -44,6 +44,8 @@ tests = testGroup "cradle"
     ,ignoreFor (BrokenForGHC [GHC92]) "multiple units not supported on 9.2"
        $ testGroup "multi-unit" (multiTests "multi-unit")
     ,testGroup "sub-directory"   [simpleSubDirectoryTest]
+    ,ignoreFor (BrokenForGHC [GHC92]) "multiple units not supported on 9.2"
+      $ testGroup "multi-unit-rexport" [multiRexportTest]
     ]
 
 loadCradleOnlyonce :: TestTree
@@ -187,6 +189,17 @@ simpleMultiDefTest variant = testCase (multiTestName variant "def-test") $ runWi
     checkDefs locs (pure [fooL])
     expectNoMoreDiagnostics 0.5
 
+multiRexportTest :: TestTree
+multiRexportTest =
+  testCase "multi-unit-reexport-test"  $ runWithExtraFiles "multi-unit-reexport" $ \dir -> do
+    let cPath = dir </> "c/C.hs"
+    cdoc <- openDoc cPath "haskell"
+    WaitForIdeRuleResult {} <- waitForAction "TypeCheck" cdoc
+    locs <- getDefinitions cdoc (Position 3 7)
+    let aPath = dir </> "a/A.hs"
+    let fooL = mkL (filePathToUri aPath) 2 0 2 3
+    checkDefs locs (pure [fooL])
+    expectNoMoreDiagnostics 0.5
 
 sessionDepsArePickedUp :: TestTree
 sessionDepsArePickedUp = testSession'