optimize ambiguity import suggestions (#1669)

ghcide/ghcide.cabal

@@ -346,6 +346,7 @@ test-suite ghcide-tests
         QuickCheck,
         quickcheck-instances,
         rope-utf16-splay,
+        regex-tdfa ^>= 1.3.1,
         safe,
         safe-exceptions,
         shake,

ghcide/src/Development/IDE/Plugin/CodeAction.hs

@@ -848,31 +848,39 @@ suggestImportDisambiguation df (Just txt) ps@(L _ HsModule {hsmodImports}) diag@
         toModuleTarget mName = ExistingImp <$> Map.lookup mName locDic
         parensed =
             "(" `T.isPrefixOf` T.strip (textInRange _range txt)
+        -- > removeAllDuplicates [1, 1, 2, 3, 2] = [3]
+        removeAllDuplicates = map head . filter ((==1) <$> length) . group . sort
+        hasDuplicate xs = length xs /= length (S.fromList xs)
         suggestions symbol mods
-            | Just targets <- mapM toModuleTarget mods =
-                sortOn fst
-                [ ( renderUniquify mode modNameText symbol
-                  , disambiguateSymbol ps diag symbol mode
-                  )
-                | (modTarget, restImports) <- oneAndOthers targets
-                , let modName = targetModuleName modTarget
-                      modNameText = T.pack $ moduleNameString modName
-                , mode <-
-                    HideOthers restImports :
-                    [ ToQualified parensed qual
-                    | ExistingImp imps <- [modTarget]
-                    , L _ qual <- nubOrd $ mapMaybe (ideclAs . unLoc)
-                        $ NE.toList imps
-                    ]
-                    ++ [ToQualified parensed modName
-                        | any (occursUnqualified symbol . unLoc)
-                            (targetImports modTarget)
-                        || case modTarget of
-                            ImplicitPrelude{} -> True
-                            _                 -> False
-                        ]
+          | hasDuplicate mods = case mapM toModuleTarget (removeAllDuplicates mods) of
+                                  Just targets -> suggestionsImpl symbol (map (, []) targets)
+                                  Nothing      -> []
+          | otherwise         = case mapM toModuleTarget mods of
+                                  Just targets -> suggestionsImpl symbol (oneAndOthers targets)
+                                  Nothing      -> []
+        suggestionsImpl symbol targetsWithRestImports = 
+            sortOn fst
+            [ ( renderUniquify mode modNameText symbol
+              , disambiguateSymbol ps diag symbol mode
+              )
+            | (modTarget, restImports) <- targetsWithRestImports
+            , let modName = targetModuleName modTarget
+                  modNameText = T.pack $ moduleNameString modName
+            , mode <-
+                [ ToQualified parensed qual
+                | ExistingImp imps <- [modTarget]
+                , L _ qual <- nubOrd $ mapMaybe (ideclAs . unLoc)
+                    $ NE.toList imps
                 ]
-            | otherwise = []
+                ++ [ToQualified parensed modName
+                    | any (occursUnqualified symbol . unLoc)
+                        (targetImports modTarget)
+                    || case modTarget of
+                        ImplicitPrelude{} -> True
+                        _                 -> False
+                    ]
+                ++ [HideOthers restImports | not (null restImports)]
+            ]
         renderUniquify HideOthers {} modName symbol =
             "Use " <> modName <> " for " <> symbol <> ", hiding other imports"
         renderUniquify (ToQualified _ qual) _ symbol =

ghcide/test/data/hiding/FVec.hs

@@ -0,0 +1,9 @@
+{-# LANGUAGE DuplicateRecordFields #-}
+
+module FVec (RecA(..), RecB(..)) where
+
+data Vec a
+
+newtype RecA a = RecA { fromList :: [a] -> Vec a }
+
+newtype RecB a = RecB { fromList :: [a] -> Vec a }

ghcide/test/data/hiding/HideQualifyDuplicateRecordFields.expected.hs

@@ -0,0 +1,10 @@
+module HideQualifyDuplicateRecordFields where
+
+import AVec
+import BVec
+import CVec
+import DVec
+import EVec
+import FVec
+
+theFun = AVec.fromList

ghcide/test/data/hiding/HideQualifyDuplicateRecordFields.hs

@@ -0,0 +1,10 @@
+module HideQualifyDuplicateRecordFields where
+
+import AVec
+import BVec
+import CVec
+import DVec
+import EVec
+import FVec
+
+theFun = fromList

ghcide/test/data/hiding/HideQualifyDuplicateRecordFieldsSelf.hs

@@ -0,0 +1,5 @@
+module HideQualifyDuplicateRecordFieldsSelf where
+
+import FVec
+
+x = fromList

ghcide/test/exe/Main.hs

@@ -93,14 +93,15 @@ import           Test.Tasty.ExpectedFailure
 import           Test.Tasty.HUnit
 import           Test.Tasty.Ingredients.Rerun
 import           Test.Tasty.QuickCheck
-import Data.IORef
-import Ide.PluginUtils (pluginDescToIdePlugins)
-import Control.Concurrent.Async
-import Ide.Types
-import Data.String (IsString(fromString))
-import qualified Language.LSP.Types as LSP
-import Data.IORef.Extra (atomicModifyIORef_)
-import qualified Development.IDE.Plugin.HLS.GhcIde as Ghcide
+import           Data.IORef
+import           Ide.PluginUtils (pluginDescToIdePlugins)
+import           Control.Concurrent.Async
+import           Ide.Types
+import           Data.String                              (IsString(fromString))
+import qualified Language.LSP.Types                       as LSP
+import           Data.IORef.Extra                         (atomicModifyIORef_)
+import qualified Development.IDE.Plugin.HLS.GhcIde        as Ghcide
+import           Text.Regex.TDFA                          ((=~))
 
 waitForProgressBegin :: Session ()
 waitForProgressBegin = skipManyTill anyMessage $ satisfyMaybe $ \case
@@ -1673,6 +1674,23 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             compareHideFunctionTo [(8,9),(10,8)]
                 "Replace with qualified: E.fromList"
                 "HideFunction.expected.qualified.fromList.E.hs"
+        , testCase "Hide DuplicateRecordFields" $
+            compareTwo
+                "HideQualifyDuplicateRecordFields.hs" [(9, 9)]
+                "Replace with qualified: AVec.fromList"
+                "HideQualifyDuplicateRecordFields.expected.hs"
+        , testCase "Duplicate record fields should not be imported" $ do
+          withTarget ("HideQualifyDuplicateRecordFields" <.> ".hs") [(9, 9)] $
+            \_ actions -> do
+              liftIO $
+                assertBool "Hidings should not be presented while DuplicateRecordFields exists" $
+                  all not [ actionTitle =~ T.pack "Use ([A-Za-z][A-Za-z0-9]*) for fromList, hiding other imports"
+                      | InR CodeAction { _title = actionTitle } <- actions]
+          withTarget ("HideQualifyDuplicateRecordFieldsSelf" <.> ".hs") [(4, 4)] $
+            \_ actions -> do
+              liftIO $
+                assertBool "ambiguity from DuplicateRecordFields should not be imported" $
+                  null actions
         ]
     , testGroup "(++)"
         [ testCase "Prelude, parensed" $
@@ -1708,7 +1726,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             contentAfterAction <- documentContents doc
             liftIO $ T.replace "\r\n" "\n" expected @=? contentAfterAction
     compareHideFunctionTo = compareTwo "HideFunction.hs"
-    auxFiles = ["AVec.hs", "BVec.hs", "CVec.hs", "DVec.hs", "EVec.hs"]
+    auxFiles = ["AVec.hs", "BVec.hs", "CVec.hs", "DVec.hs", "EVec.hs", "FVec.hs"]
     withTarget file locs k = withTempDir $ \dir -> runInDir dir $ do
         liftIO $ mapM_ (\fp -> copyFile (hidingDir </> fp) $ dir </> fp)
             $ file : auxFiles