From b35aa37d7e14ba3084d83431df4ce6b45e752902 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 03:20:55 +0900
Subject: [PATCH 01/43] wip

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 193 +++++++++++++++---
 .../IDE/Plugin/CodeAction/ExactPrint.hs       |   9 +
 2 files changed, 168 insertions(+), 34 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 1dbddf9e6a..09c3e0a484 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -3,6 +3,7 @@
 
 {-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE CPP                   #-}
+{-# LANGUAGE LambdaCase #-}
 #include "ghc-api-version.h"
 
 -- | Go to the definition of a variable.
@@ -13,14 +14,31 @@ module Development.IDE.Plugin.CodeAction
     , matchRegExMultipleImports
     ) where
 
-import Control.Monad (join, guard)
-import Development.IDE.GHC.Compat
-import Development.IDE.Core.Rules
+import Bag (isEmptyBag)
+import Control.Applicative ((<|>))
+import Control.Arrow (second, (>>>))
+import Control.Concurrent.Extra (readVar)
+import Control.Monad (guard, join)
+import Data.Char
+import Data.Function
+import Data.Functor
+import qualified Data.HashMap.Strict as Map
+import qualified Data.HashSet as Set
+import Data.List.Extra
+import Data.List.NonEmpty (NonEmpty ((:|)))
+import qualified Data.List.NonEmpty as NE
+import Data.Maybe
+import Data.Ord (Down (Down))
+import qualified Data.Rope.UTF16 as Rope
+import qualified Data.Text as T
 import Development.IDE.Core.RuleTypes
+import Development.IDE.Core.Rules
 import Development.IDE.Core.Service
 import Development.IDE.Core.Shake
+import Development.IDE.GHC.Compat
 import Development.IDE.GHC.Error
 import Development.IDE.GHC.ExactPrint
+import Development.IDE.GHC.Util (printRdrName)
 import Development.IDE.Plugin.CodeAction.ExactPrint
 import Development.IDE.Plugin.CodeAction.PositionIndexed
 import Development.IDE.Plugin.CodeAction.RuleTypes
@@ -29,31 +47,18 @@ import Development.IDE.Plugin.TypeLenses (suggestSignature)
 import Development.IDE.Types.Exports
 import Development.IDE.Types.Location
 import Development.IDE.Types.Options
-import qualified Data.HashMap.Strict as Map
+import Ide.PluginUtils (subRange)
+import Ide.Types
 import qualified Language.Haskell.LSP.Core as LSP
-import Language.Haskell.LSP.VFS
 import Language.Haskell.LSP.Types
-import qualified Data.Rope.UTF16 as Rope
-import Data.Char
-import Data.Maybe
-import Data.List.Extra
-import Data.List.NonEmpty (NonEmpty((:|)))
-import qualified Data.List.NonEmpty as NE
-import qualified Data.Text as T
-import Text.Regex.TDFA (mrAfter, (=~), (=~~))
+import Language.Haskell.LSP.VFS
 import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
-import Data.Function
-import Control.Arrow ((>>>))
-import Data.Functor
-import Control.Applicative ((<|>))
+import Retrie.GHC (fsLit, mkRealSrcLoc, mkRealSrcSpan)
 import Safe (atMay)
-import Bag (isEmptyBag)
-import qualified Data.HashSet as Set
-import Control.Concurrent.Extra (readVar)
-import Development.IDE.GHC.Util (printRdrName)
-import Ide.PluginUtils (subRange)
-import Ide.Types
-
+import Text.Regex.TDFA (mrAfter, (=~), (=~~))
+import Retrie (unpackFS)
+import Retrie.GHC (mkVarOcc)
+import Language.Haskell.GHC.ExactPrint.Transform (uniqueSrcSpanT)
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
   (defaultPluginDescriptor plId)
@@ -96,9 +101,9 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
           | x <- xs
           , Just ps <- [annotatedPS]
           , Just dynflags <- [df]
-          , (title, graft) <- suggestExactAction exportsMap dynflags ps x
-          , let edit = either error id $
-                        rewriteToEdit dynflags uri (annsA ps) graft
+          , (title, grafts) <- suggestExactAction exportsMap dynflags ps x
+          , let edit = foldMap (either error id .
+                        rewriteToEdit dynflags uri (annsA ps)) grafts
           ]
       actions'' = caRemoveRedundantImports parsedModule text diag xs uri
                <> actions
@@ -115,12 +120,13 @@ suggestExactAction ::
   DynFlags ->
   Annotated ParsedSource ->
   Diagnostic ->
-  [(T.Text, Rewrite)]
+  [(T.Text, [Rewrite])]
 suggestExactAction exportsMap df ps x =
   concat
     [ suggestConstraint df (astA ps) x
     , suggestImplicitParameter (astA ps) x
     , suggestExtendImport exportsMap (astA ps) x
+    , suggestImportDisambiguation exportsMap (astA ps) x
     ]
 
 suggestAction
@@ -664,7 +670,7 @@ getIndentedGroupsBy pred inp = case dropWhile (not.pred) inp of
 indentation :: T.Text -> Int
 indentation = T.length . T.takeWhile isSpace
 
-suggestExtendImport :: ExportsMap -> ParsedSource -> Diagnostic -> [(T.Text, Rewrite)]
+suggestExtendImport :: ExportsMap -> ParsedSource -> Diagnostic -> [(T.Text, [Rewrite])]
 suggestExtendImport exportsMap (L _ HsModule {hsmodImports}) Diagnostic{_range=_range,..}
     | Just [binding, mod, srcspan] <-
       matchRegexUnifySpaces _message
@@ -685,7 +691,7 @@ suggestExtendImport exportsMap (L _ HsModule {hsmodImports}) Diagnostic{_range=_
             Just decl <- findImportDeclByRange decls range,
             Just ident <- lookupExportMap binding mod
           = [ ( "Add " <> renderImportStyle importStyle <> " to the import list of " <> mod
-              , uncurry extendImport (unImportStyle importStyle) decl
+              , [uncurry extendImport (unImportStyle importStyle) decl]
               )
             | importStyle <- NE.toList $ importStyles ident
             ]
@@ -703,6 +709,114 @@ suggestExtendImport exportsMap (L _ HsModule {hsmodImports}) Diagnostic{_range=_
                 , parent = Nothing
                 , isDatacon = False}
 
+data HidingMode = HideOthers [LImportDecl GhcPs] | ToQualified ModuleName
+    deriving (Show)
+
+oneAndOthers :: [a] -> [(a, [a])]
+oneAndOthers = go
+    where
+        go [] = []
+        go (x : xs) = (x, xs) : map (second (x :)) (go xs)
+
+-- | Suggests disambiguation for ambiguous symbols.
+suggestImportDisambiguation ::
+    ExportsMap ->
+    ParsedSource ->
+    Diagnostic ->
+    [(T.Text, [Rewrite])]
+suggestImportDisambiguation exportsMap (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
+    | Just [ambiguous] <-
+        matchRegexUnifySpaces
+            _message
+            "^Ambiguous occurrence ‘([^’]+)’"
+      , Just modules <-
+            map last
+                <$> allMatchRegexUnifySpaces _message "imported from ‘([^’]+)’" =
+        suggestions ambiguous modules
+    | otherwise = []
+    where
+        locDic =
+            Map.fromList $
+                map
+                    ( \i@(L _ idecl) ->
+                        ( T.pack $ moduleNameString $ unLoc $ ideclName idecl
+                        , i
+                        )
+                    )
+                    hsmodImports
+        suggestions symbol mods
+            | Just targets <- mapM (`Map.lookup` locDic) mods =
+                [ ( renderUniquify mode modNameText symbol
+                  , disambiguateSymbol diag symbol lidecl mode
+                  )
+                | (lidecl@(L _ ImportDecl {..}), restImports) <- oneAndOthers targets
+                , let modName = unLoc ideclName
+                      modNameText = T.pack $ moduleNameString modName
+                , mode <-
+                    [ ToQualified qual
+                    | L _ qual <- maybeToList ideclAs
+                    ]
+                        ++ [HideOthers restImports]
+                        ++ [ToQualified modName]
+                ]
+            | otherwise = []
+        renderUniquify HideOthers {} modName symbol =
+            "Use the import from " <> modName <> " for " <> symbol <> ", hiding other imports"
+        renderUniquify (ToQualified qual) _ symbol =
+            "Replace with qualified: "
+                <> T.pack (moduleNameString qual)
+                <> "."
+                <> symbol
+        lookupExportMap binding mod
+            | Just match <- Map.lookup binding (getExportsMap exportsMap)
+              , [(ident, _)] <- filter (\(_, m) -> mod == m) (Set.toList match) =
+                Just ident
+            -- fallback to using GHC suggestion even though it is not always correct
+            | otherwise =
+                Just
+                    IdentInfo
+                        { name = binding
+                        , rendered = binding
+                        , parent = Nothing
+                        , isDatacon = False
+                        }
+
+disambiguateSymbol ::
+    Diagnostic ->
+    T.Text ->
+    GenLocated SrcSpan (ImportDecl GhcPs) ->
+    HidingMode ->
+    [Rewrite]
+disambiguateSymbol Diagnostic {..} symbol (L loc _) = \case
+    (HideOthers hiddens0) ->
+        [ hideSymbol symbol idecl
+        | idecl <- sortOn (Down . getLoc) hiddens0
+        ]
+    (ToQualified qualMod) ->
+        [ Rewrite (rangeToSrcSpan theFile _range) $ \_ -> do
+            spn <- uniqueSrcSpanT
+            pure
+                ( L spn $
+                    HsVar NoExt $
+                        L spn $
+                            Qual qualMod (mkVarOcc $ T.unpack symbol) ::
+                    LHsExpr GhcPs
+                )
+        ]
+        where
+            theFile
+                | RealSrcSpan real <- loc = unpackFS $ srcSpanFile real
+                | otherwise = "<dummy>"
+
+rangeToSrcSpan :: String -> Range -> SrcSpan
+rangeToSrcSpan file range = RealSrcSpan $ rangeToRealSrcSpan file range
+
+rangeToRealSrcSpan :: String -> Range -> RealSrcSpan
+rangeToRealSrcSpan file (Range (Position startLn startCh) (Position endLn endCh)) =
+    mkRealSrcSpan
+      (mkRealSrcLoc (fsLit file) (startLn + 1) (startCh + 1))
+      (mkRealSrcLoc (fsLit file) (endLn + 1) (endCh + 1))
+
 findImportDeclByRange :: [LImportDecl GhcPs] -> Range -> Maybe (LImportDecl GhcPs)
 findImportDeclByRange xs range = find (\(L l _)-> srcSpanToRange l == Just range) xs
 
@@ -720,13 +834,13 @@ suggestFixConstructorImport _ Diagnostic{_range=_range,..}
     in [("Fix import of " <> fixedImport, [TextEdit _range fixedImport])]
   | otherwise = []
 -- | Suggests a constraint for a declaration for which a constraint is missing.
-suggestConstraint :: DynFlags -> ParsedSource -> Diagnostic -> [(T.Text, Rewrite)]
+suggestConstraint :: DynFlags -> ParsedSource -> Diagnostic -> [(T.Text, [Rewrite])]
 suggestConstraint df parsedModule diag@Diagnostic {..}
   | Just missingConstraint <- findMissingConstraint _message
   = let codeAction = if _message =~ ("the type signature for:" :: String)
                         then suggestFunctionConstraint df parsedModule
                         else suggestInstanceConstraint df parsedModule
-     in codeAction diag missingConstraint
+     in map (second pure) $ codeAction diag missingConstraint
   | otherwise = []
     where
       findMissingConstraint :: T.Text -> Maybe T.Text
@@ -782,14 +896,14 @@ suggestInstanceConstraint df (L _ HsModule {hsmodDecls}) Diagnostic {..} missing
 suggestImplicitParameter ::
   ParsedSource ->
   Diagnostic ->
-  [(T.Text, Rewrite)]
+  [(T.Text, [Rewrite])]
 suggestImplicitParameter (L _ HsModule {hsmodDecls}) Diagnostic {_message, _range}
   | Just [implicitT] <- matchRegexUnifySpaces _message "Unbound implicit parameter \\(([^:]+::.+)\\) arising",
     Just (L _ (ValD _ FunBind {fun_id = L _ funId})) <- findDeclContainingLoc (_start _range) hsmodDecls,
     Just (TypeSig _ _ HsWC {hswc_body = HsIB {hsib_body}}) <- findSigOfDecl (== funId) hsmodDecls
     =
       [( "Add " <> implicitT <> " to the context of " <> T.pack (printRdrName funId)
-        , appendConstraint (T.unpack implicitT) hsib_body)]
+        , [appendConstraint (T.unpack implicitT) hsib_body])]
   | otherwise = []
 
 findTypeSignatureName :: T.Text -> Maybe T.Text
@@ -1107,11 +1221,22 @@ rangesForBinding' _ _ = []
 matchRegexUnifySpaces :: T.Text -> T.Text -> Maybe [T.Text]
 matchRegexUnifySpaces message = matchRegex (unifySpaces message)
 
+-- | 'allMatchRegex' combined with 'unifySpaces'
+allMatchRegexUnifySpaces :: T.Text -> T.Text -> Maybe [[T.Text]]
+allMatchRegexUnifySpaces message =
+    allMatchRegex (unifySpaces message)
+
 -- | Returns Just (the submatches) for the first capture, or Nothing.
 matchRegex :: T.Text -> T.Text -> Maybe [T.Text]
 matchRegex message regex = case message =~~ regex of
     Just (_ :: T.Text, _ :: T.Text, _ :: T.Text, bindings) -> Just bindings
     Nothing -> Nothing
+
+-- | Returns Just (all matches) for the first capture, or Nothing.
+allMatchRegex :: T.Text -> T.Text -> Maybe [[T.Text]]
+allMatchRegex message regex = message =~~ regex
+
+
 unifySpaces :: T.Text -> T.Text
 unifySpaces    = T.unwords . T.words
 
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index a35c793c16..98b1182a57 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -10,6 +10,8 @@ module Development.IDE.Plugin.CodeAction.ExactPrint
     -- * Utilities
     appendConstraint,
     extendImport,
+    hideSymbol,
+    liftParseAST,
   )
 where
 
@@ -298,3 +300,10 @@ unqalDP paren =
       else pure
   )
     (G AnnVal, dp00)
+
+------------------------------------------------------------------------------
+-- | Hide a symbol from import declaration
+hideSymbol
+    :: String -> LImportDecl GhcPs -> Rewrite
+hideSymbol symbol (L loc ImportDecl{..}) = Rewrite loc $ \df ->
+    pure (undefined :: LImportDecl GhcPs)

From cbcb0f0c94b44c4e7303af0f6e5b206cd0ff87ca Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 04:04:11 +0900
Subject: [PATCH 02/43] Draft completed

---
 .../src/Development/IDE/Plugin/CodeAction.hs  |  4 +-
 .../IDE/Plugin/CodeAction/ExactPrint.hs       | 75 +++++++++++++++++--
 2 files changed, 72 insertions(+), 7 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 09c3e0a484..20e1b00bae 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -787,7 +787,7 @@ disambiguateSymbol ::
     GenLocated SrcSpan (ImportDecl GhcPs) ->
     HidingMode ->
     [Rewrite]
-disambiguateSymbol Diagnostic {..} symbol (L loc _) = \case
+disambiguateSymbol Diagnostic {..} (T.unpack -> symbol) (L loc _) = \case
     (HideOthers hiddens0) ->
         [ hideSymbol symbol idecl
         | idecl <- sortOn (Down . getLoc) hiddens0
@@ -799,7 +799,7 @@ disambiguateSymbol Diagnostic {..} symbol (L loc _) = \case
                 ( L spn $
                     HsVar NoExt $
                         L spn $
-                            Qual qualMod (mkVarOcc $ T.unpack symbol) ::
+                            Qual qualMod (mkVarOcc symbol) ::
                     LHsExpr GhcPs
                 )
         ]
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index 98b1182a57..1abcc8f560 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE EmptyCase #-}
 {-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -22,7 +23,7 @@ import Data.Data (Data)
 import Data.Functor
 import qualified Data.HashMap.Strict as HMap
 import qualified Data.Map.Strict as Map
-import Data.Maybe (fromJust)
+import Data.Maybe (fromJust, mapMaybe)
 import qualified Data.Text as T
 import Development.IDE.GHC.Compat hiding (parseExpr)
 import Development.IDE.GHC.ExactPrint
@@ -33,6 +34,8 @@ import Language.Haskell.GHC.ExactPrint.Types (DeltaPos (DP), KeywordId (G), mkAn
 import Language.Haskell.LSP.Types
 import OccName
 import Outputable (ppr, showSDocUnsafe)
+import Retrie.GHC (unpackFS)
+import FieldLabel (flLabel)
 
 ------------------------------------------------------------------------------
 
@@ -303,7 +306,69 @@ unqalDP paren =
 
 ------------------------------------------------------------------------------
 -- | Hide a symbol from import declaration
-hideSymbol
-    :: String -> LImportDecl GhcPs -> Rewrite
-hideSymbol symbol (L loc ImportDecl{..}) = Rewrite loc $ \df ->
-    pure (undefined :: LImportDecl GhcPs)
+hideSymbol ::
+    String -> LImportDecl GhcPs -> Rewrite
+hideSymbol symbol lidecl@(L loc ImportDecl {..}) =
+    case ideclHiding of
+        Nothing -> Rewrite loc $ extendHiding symbol lidecl Nothing
+        Just (True, hides) -> Rewrite loc $ extendHiding symbol lidecl (Just hides)
+        Just (False, imports) -> Rewrite loc $ deleteFromImport symbol lidecl imports
+hideSymbol _ (L _ (XImportDecl _)) =
+    error "cannot happen"
+
+extendHiding ::
+    String ->
+    LImportDecl GhcPs ->
+    Maybe (Located [LIE GhcPs]) ->
+    DynFlags ->
+    TransformT (Either String) (LImportDecl GhcPs)
+extendHiding symbol (L l idecls) mlies df = do
+    L l' lies <- case mlies of
+        Nothing -> flip L [] <$> uniqueSrcSpanT
+        Just pr -> pure pr
+    let hasSibling = not $ null lies
+    src <- uniqueSrcSpanT
+    top <- uniqueSrcSpanT
+    rdr <- liftParseAST df symbol
+    let lie = L src $ IEName rdr
+        x = L top $ IEVar noExtField lie
+    when hasSibling $
+      addTrailingCommaT (last lies)
+    addSimpleAnnT x (DP (0, if hasSibling then 1 else 0)) []
+    addSimpleAnnT rdr dp00 $ unqalDP $ hasParen symbol
+    -- Parens are attachted to `lies`, so if `lies` was empty previously,
+    -- we need change the ann key from `[]` to `:` to keep parens and other anns.
+    unless hasSibling $
+      transferAnn (L l' lies) (L l' [x]) id
+    return $ L l idecls {ideclHiding = Just (True, L l' $ lies ++ [x])}
+
+deleteFromImport ::
+    String ->
+    LImportDecl GhcPs ->
+    Located [LIE GhcPs] ->
+    DynFlags ->
+    TransformT (Either String) (LImportDecl GhcPs)
+deleteFromImport symbol (L l idecls) (L lieLoc lies) _ =
+    pure $ L l $ idecls
+        { ideclHiding = Just (False, L lieLoc deletedLies)
+        }
+    where
+        deletedLies =
+            mapMaybe killLie lies
+        killLie :: LIE GhcPs -> Maybe (LIE GhcPs)
+        killLie v@(L _ (IEVar _ (L _ (unIEWrappedName -> nam))))
+            | nam == symbol  = Nothing
+            | otherwise = Just v
+        killLie v@(L _ (IEThingAbs _ (L _ (unIEWrappedName -> nam))))
+            | nam == symbol = Nothing
+            | otherwise = Just v
+
+        killLie (L lieL (IEThingWith xt ty@(L _ (unIEWrappedName -> nam)) wild cons flds))
+            | nam == symbol = Nothing
+            | otherwise = Just $
+                L lieL $ IEThingWith xt ty wild
+                  (filter ((/= symbol) . unIEWrappedName . unLoc) cons)
+                  (filter ((/= symbol) . unpackFS . flLabel . unLoc) flds)
+        killLie v = Just v
+
+

From a0682573823fcbdcd51adb6f56174b831ed8c674 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 04:05:32 +0900
Subject: [PATCH 03/43] Removes Unuseds

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 20e1b00bae..27b72478c5 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -767,19 +767,6 @@ suggestImportDisambiguation exportsMap (L _ HsModule {hsmodImports}) diag@Diagno
                 <> T.pack (moduleNameString qual)
                 <> "."
                 <> symbol
-        lookupExportMap binding mod
-            | Just match <- Map.lookup binding (getExportsMap exportsMap)
-              , [(ident, _)] <- filter (\(_, m) -> mod == m) (Set.toList match) =
-                Just ident
-            -- fallback to using GHC suggestion even though it is not always correct
-            | otherwise =
-                Just
-                    IdentInfo
-                        { name = binding
-                        , rendered = binding
-                        , parent = Nothing
-                        , isDatacon = False
-                        }
 
 disambiguateSymbol ::
     Diagnostic ->

From e506ddf6050d713fe652096c67e104f1f72356e7 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 04:14:57 +0900
Subject: [PATCH 04/43] Redundant extension

---
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index 1abcc8f560..cfacb96099 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE EmptyCase #-}
 {-# LANGUAGE DerivingStrategies #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE OverloadedStrings #-}

From a995c5e5af33a034e50bd788cc415a054f801c5a Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 04:21:03 +0900
Subject: [PATCH 05/43] linting

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 27b72478c5..50ce5ad7ff 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -49,16 +49,16 @@ import Development.IDE.Types.Location
 import Development.IDE.Types.Options
 import Ide.PluginUtils (subRange)
 import Ide.Types
+import Language.Haskell.GHC.ExactPrint.Transform (uniqueSrcSpanT)
 import qualified Language.Haskell.LSP.Core as LSP
 import Language.Haskell.LSP.Types
 import Language.Haskell.LSP.VFS
 import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
-import Retrie.GHC (fsLit, mkRealSrcLoc, mkRealSrcSpan)
+import Retrie (unpackFS)
+import Retrie.GHC (fsLit, mkRealSrcLoc, mkRealSrcSpan, mkVarOcc)
 import Safe (atMay)
 import Text.Regex.TDFA (mrAfter, (=~), (=~~))
-import Retrie (unpackFS)
-import Retrie.GHC (mkVarOcc)
-import Language.Haskell.GHC.ExactPrint.Transform (uniqueSrcSpanT)
+
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
   (defaultPluginDescriptor plId)
@@ -126,7 +126,7 @@ suggestExactAction exportsMap df ps x =
     [ suggestConstraint df (astA ps) x
     , suggestImplicitParameter (astA ps) x
     , suggestExtendImport exportsMap (astA ps) x
-    , suggestImportDisambiguation exportsMap (astA ps) x
+    , suggestImportDisambiguation (astA ps) x
     ]
 
 suggestAction
@@ -720,11 +720,10 @@ oneAndOthers = go
 
 -- | Suggests disambiguation for ambiguous symbols.
 suggestImportDisambiguation ::
-    ExportsMap ->
     ParsedSource ->
     Diagnostic ->
     [(T.Text, [Rewrite])]
-suggestImportDisambiguation exportsMap (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
+suggestImportDisambiguation (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | Just [ambiguous] <-
         matchRegexUnifySpaces
             _message

From 169db8f62740891fb903d612ea139cee8720152d Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 04:25:37 +0900
Subject: [PATCH 06/43] Makes HLint happy

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs       | 11 +++++------
 .../Development/IDE/Plugin/CodeAction/ExactPrint.hs   |  5 ++---
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 50ce5ad7ff..29cc24a478 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -3,7 +3,6 @@
 
 {-# LANGUAGE DuplicateRecordFields #-}
 {-# LANGUAGE CPP                   #-}
-{-# LANGUAGE LambdaCase #-}
 #include "ghc-api-version.h"
 
 -- | Go to the definition of a variable.
@@ -316,8 +315,8 @@ suggestDeleteUnusedBinding
             let findSig (L (RealSrcSpan l) (SigD _ sig)) = findRelatedSigSpan indexedContent name l sig
                 findSig _ = []
             in
-              [extendForSpaces indexedContent $ toRange l]
-              ++ concatMap findSig hsmodDecls
+              extendForSpaces indexedContent (toRange l) :
+              concatMap findSig hsmodDecls
           _ -> concatMap (findRelatedSpanForMatch indexedContent name) matches
       findRelatedSpans _ _ _ = []
 
@@ -392,7 +391,7 @@ suggestDeleteUnusedBinding
         then
           let findSig (L (RealSrcSpan l) sig) = findRelatedSigSpan indexedContent name l sig
               findSig _ = []
-          in [extendForSpaces indexedContent $ toRange l] ++ concatMap findSig lsigs
+          in extendForSpaces indexedContent (toRange l) : concatMap findSig lsigs
         else concatMap (findRelatedSpanForMatch indexedContent name) matches
       findRelatedSpanForHsBind _ _ _ _ = []
 
@@ -727,7 +726,7 @@ suggestImportDisambiguation (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | Just [ambiguous] <-
         matchRegexUnifySpaces
             _message
-            "^Ambiguous occurrence ‘([^’]+)’"
+            "Ambiguous occurrence ‘([^’]+)’"
       , Just modules <-
             map last
                 <$> allMatchRegexUnifySpaces _message "imported from ‘([^’]+)’" =
@@ -773,7 +772,7 @@ disambiguateSymbol ::
     GenLocated SrcSpan (ImportDecl GhcPs) ->
     HidingMode ->
     [Rewrite]
-disambiguateSymbol Diagnostic {..} (T.unpack -> symbol) (L loc _) = \case
+disambiguateSymbol Diagnostic {..} (T.unpack -> symbol) (L loc _) h = case h of
     (HideOthers hiddens0) ->
         [ hideSymbol symbol idecl
         | idecl <- sortOn (Down . getLoc) hiddens0
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index cfacb96099..b186b19a6f 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -150,9 +150,8 @@ appendConstraint constraintT = go
       lTop <- uniqueSrcSpanT
       let context = L lContext [constraint]
       addSimpleAnnT context (DP (0, 1)) $
-        [ (G AnnDarrow, DP (0, 1))
-        ]
-          ++ concat
+        (G AnnDarrow, DP (0, 1))
+        : concat
             [ [ (G AnnOpenP, dp00),
                 (G AnnCloseP, dp00)
               ]

From 4e92ee9f70e06ad9a87da1bc8f361869a7013eb0 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 04:41:20 +0900
Subject: [PATCH 07/43] tweak for transfer annotation logic (not working)

---
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index b186b19a6f..1b7c71ad0d 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -334,10 +334,8 @@ extendHiding symbol (L l idecls) mlies df = do
       addTrailingCommaT (last lies)
     addSimpleAnnT x (DP (0, if hasSibling then 1 else 0)) []
     addSimpleAnnT rdr dp00 $ unqalDP $ hasParen symbol
-    -- Parens are attachted to `lies`, so if `lies` was empty previously,
-    -- we need change the ann key from `[]` to `:` to keep parens and other anns.
-    unless hasSibling $
-      transferAnn (L l' lies) (L l' [x]) id
+    unless hasSibling $ forM_ mlies $ \lies0 ->
+      transferAnn lies0 (L l' [x]) id
     return $ L l idecls {ideclHiding = Just (True, L l' $ lies ++ [x])}
 
 deleteFromImport ::

From 72477dda6998fac96329173fab00543990484ef1 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 22:40:56 +0900
Subject: [PATCH 08/43] Initial implementation done

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 158 ++++++++++++------
 .../IDE/Plugin/CodeAction/ExactPrint.hs       |  65 +++++--
 2 files changed, 159 insertions(+), 64 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 29cc24a478..bf94a4b944 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -17,17 +17,20 @@ import Bag (isEmptyBag)
 import Control.Applicative ((<|>))
 import Control.Arrow (second, (>>>))
 import Control.Concurrent.Extra (readVar)
+import Control.Lens (foldMapBy, (^.))
 import Control.Monad (guard, join)
 import Data.Char
+import Data.Coerce (coerce)
+import qualified Data.DList as DL
 import Data.Function
 import Data.Functor
 import qualified Data.HashMap.Strict as Map
 import qualified Data.HashSet as Set
+import Data.Hashable (Hashable)
 import Data.List.Extra
 import Data.List.NonEmpty (NonEmpty ((:|)))
 import qualified Data.List.NonEmpty as NE
 import Data.Maybe
-import Data.Ord (Down (Down))
 import qualified Data.Rope.UTF16 as Rope
 import qualified Data.Text as T
 import Development.IDE.Core.RuleTypes
@@ -46,18 +49,18 @@ import Development.IDE.Plugin.TypeLenses (suggestSignature)
 import Development.IDE.Types.Exports
 import Development.IDE.Types.Location
 import Development.IDE.Types.Options
+import qualified GHC.LanguageExtensions as Lang
 import Ide.PluginUtils (subRange)
 import Ide.Types
-import Language.Haskell.GHC.ExactPrint.Transform (uniqueSrcSpanT)
 import qualified Language.Haskell.LSP.Core as LSP
 import Language.Haskell.LSP.Types
 import Language.Haskell.LSP.VFS
 import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
-import Retrie (unpackFS)
-import Retrie.GHC (fsLit, mkRealSrcLoc, mkRealSrcSpan, mkVarOcc)
+import Retrie.GHC (mkVarOcc)
 import Safe (atMay)
 import Text.Regex.TDFA (mrAfter, (=~), (=~~))
-
+import Language.Haskell.LSP.Types.Lens (start, character, end, line)
+import OccName (parenSymOcc)
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
   (defaultPluginDescriptor plId)
@@ -101,8 +104,26 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
           , Just ps <- [annotatedPS]
           , Just dynflags <- [df]
           , (title, grafts) <- suggestExactAction exportsMap dynflags ps x
-          , let edit = foldMap (either error id .
+          , let edit = foldMapBy unionWSEdit mempty (either error id .
                         rewriteToEdit dynflags uri (annsA ps)) grafts
+          ] ++
+          [mkCA title [x] edit
+          | x <- xs
+          , ps <- maybeToList annotatedPS
+          , dynflags <- maybeToList df
+          , (title, edRewrs) <-
+                suggestImportDisambiguation dynflags (astA ps) x
+          , let edit =
+                    foldMapBy unionWSEdit mempty
+                    (either
+                        (\te -> WorkspaceEdit
+                                { _changes = Just $ Map.singleton uri $ List [te]
+                                , _documentChanges = Nothing }
+                        )
+                        (either error id .
+                        rewriteToEdit dynflags uri (annsA ps))
+                    ) edRewrs
+
           ]
       actions'' = caRemoveRedundantImports parsedModule text diag xs uri
                <> actions
@@ -110,6 +131,19 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
                <> caRemoveInvalidExports parsedModule text diag xs uri
     pure $ Right $ List actions''
 
+-- | Semigroup instance just overrides duplicated keys in the first argument
+unionWSEdit :: WorkspaceEdit -> WorkspaceEdit -> WorkspaceEdit
+unionWSEdit (WorkspaceEdit a b) (WorkspaceEdit c d) =
+    -- FIXME: Want to use monoidal-containers, but it supports aeson <1.5 only...
+    WorkspaceEdit (runCatHashMap <$> fmap CatHashMap a <> fmap CatHashMap c)
+        (b <> d)
+
+newtype CatHashMap k v = CatHashMap { runCatHashMap :: Map.HashMap k v }
+instance (Eq k, Hashable k, Semigroup v) => Semigroup (CatHashMap k v) where
+  (<>) = coerce $ Map.unionWith @k @v (<>)
+instance (Eq k, Hashable k, Semigroup v) => Monoid (CatHashMap k v) where
+  mempty = CatHashMap mempty
+
 mkCA :: T.Text -> [Diagnostic] -> WorkspaceEdit -> CAResult
 mkCA title diags edit =
   CACodeAction $ CodeAction title (Just CodeActionQuickFix) (Just $ List diags) (Just edit) Nothing
@@ -125,7 +159,6 @@ suggestExactAction exportsMap df ps x =
     [ suggestConstraint df (astA ps) x
     , suggestImplicitParameter (astA ps) x
     , suggestExtendImport exportsMap (astA ps) x
-    , suggestImportDisambiguation (astA ps) x
     ]
 
 suggestAction
@@ -708,7 +741,13 @@ suggestExtendImport exportsMap (L _ HsModule {hsmodImports}) Diagnostic{_range=_
                 , parent = Nothing
                 , isDatacon = False}
 
-data HidingMode = HideOthers [LImportDecl GhcPs] | ToQualified ModuleName
+data HidingMode = HideOthers [ModuleTarget]
+                | ToQualified ModuleName
+    deriving (Show)
+
+data ModuleTarget
+    = ExistingImp (NonEmpty (LImportDecl GhcPs))
+    | ImplicitPrelude [LImportDecl GhcPs]
     deriving (Show)
 
 oneAndOthers :: [a] -> [(a, [a])]
@@ -717,12 +756,16 @@ oneAndOthers = go
         go [] = []
         go (x : xs) = (x, xs) : map (second (x :)) (go xs)
 
+isPreludeImplicit :: DynFlags -> Bool
+isPreludeImplicit = xopt Lang.ImplicitPrelude
+
 -- | Suggests disambiguation for ambiguous symbols.
 suggestImportDisambiguation ::
+    DynFlags ->
     ParsedSource ->
     Diagnostic ->
-    [(T.Text, [Rewrite])]
-suggestImportDisambiguation (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
+    [(T.Text, [Either TextEdit Rewrite])]
+suggestImportDisambiguation df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | Just [ambiguous] <-
         matchRegexUnifySpaces
             _message
@@ -734,28 +777,38 @@ suggestImportDisambiguation (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | otherwise = []
     where
         locDic =
-            Map.fromList $
+            fmap (NE.fromList . DL.toList) $
+            Map.fromListWith (<>) $
                 map
                     ( \i@(L _ idecl) ->
                         ( T.pack $ moduleNameString $ unLoc $ ideclName idecl
-                        , i
+                        , DL.singleton i
                         )
                     )
                     hsmodImports
+        toModuleTarget "Prelude"
+            | isPreludeImplicit df
+             = Just $ ImplicitPrelude $
+                maybe [] NE.toList (Map.lookup "Prelude" locDic)
+        toModuleTarget mName = ExistingImp <$> Map.lookup mName locDic
+
         suggestions symbol mods
-            | Just targets <- mapM (`Map.lookup` locDic) mods =
+            | Just targets <- mapM toModuleTarget mods =
+                sortOn fst
                 [ ( renderUniquify mode modNameText symbol
-                  , disambiguateSymbol diag symbol lidecl mode
+                  , disambiguateSymbol df ps diag symbol mode
                   )
-                | (lidecl@(L _ ImportDecl {..}), restImports) <- oneAndOthers targets
-                , let modName = unLoc ideclName
+                | (modTarget, restImports) <- oneAndOthers targets
+                , let modName = targetModuleName modTarget
                       modNameText = T.pack $ moduleNameString modName
                 , mode <-
+                    HideOthers restImports :
                     [ ToQualified qual
-                    | L _ qual <- maybeToList ideclAs
+                    | ExistingImp imps <- [modTarget]
+                    , L _ qual <- nubOrd $ mapMaybe (ideclAs . unLoc)
+                        $ NE.toList imps
                     ]
-                        ++ [HideOthers restImports]
-                        ++ [ToQualified modName]
+                    ++ [ToQualified modName]
                 ]
             | otherwise = []
         renderUniquify HideOthers {} modName symbol =
@@ -766,41 +819,52 @@ suggestImportDisambiguation (L _ HsModule {hsmodImports}) diag@Diagnostic {..}
                 <> "."
                 <> symbol
 
+targetModuleName :: ModuleTarget -> ModuleName
+targetModuleName ImplicitPrelude{} = mkModuleName "Prelude"
+targetModuleName (ExistingImp (L _ ImportDecl{..} :| _)) =
+    unLoc ideclName
+targetModuleName (ExistingImp _) =
+    error "Cannot happen!"
+
 disambiguateSymbol ::
+    DynFlags ->
+    ParsedSource ->
     Diagnostic ->
     T.Text ->
-    GenLocated SrcSpan (ImportDecl GhcPs) ->
     HidingMode ->
-    [Rewrite]
-disambiguateSymbol Diagnostic {..} (T.unpack -> symbol) (L loc _) h = case h of
+    [Either TextEdit Rewrite]
+disambiguateSymbol df pm Diagnostic {..} (T.unpack -> symbol) = \case
     (HideOthers hiddens0) ->
-        [ hideSymbol symbol idecl
-        | idecl <- sortOn (Down . getLoc) hiddens0
+        [ Right $ hideSymbol symbol idecl
+        | ExistingImp idecls <- hiddens0
+        , idecl <- NE.toList idecls
         ]
+            ++ mconcat
+                [ if null imps
+                    then [Left $ hidePreludeSymbol df symbol pm]
+                    else Right . hideSymbol symbol <$> imps
+                | ImplicitPrelude imps <- hiddens0
+                ]
     (ToQualified qualMod) ->
-        [ Rewrite (rangeToSrcSpan theFile _range) $ \_ -> do
-            spn <- uniqueSrcSpanT
-            pure
-                ( L spn $
-                    HsVar NoExt $
-                        L spn $
-                            Qual qualMod (mkVarOcc symbol) ::
-                    LHsExpr GhcPs
-                )
-        ]
-        where
-            theFile
-                | RealSrcSpan real <- loc = unpackFS $ srcSpanFile real
-                | otherwise = "<dummy>"
-
-rangeToSrcSpan :: String -> Range -> SrcSpan
-rangeToSrcSpan file range = RealSrcSpan $ rangeToRealSrcSpan file range
-
-rangeToRealSrcSpan :: String -> Range -> RealSrcSpan
-rangeToRealSrcSpan file (Range (Position startLn startCh) (Position endLn endCh)) =
-    mkRealSrcSpan
-      (mkRealSrcLoc (fsLit file) (startLn + 1) (startCh + 1))
-      (mkRealSrcLoc (fsLit file) (endLn + 1) (endCh + 1))
+        let occSym = mkVarOcc symbol
+            rdr = Qual qualMod occSym
+        in [Left $ TextEdit _range
+            $ T.pack $ showSDoc df
+            $ parenSymOcc occSym
+            $ ppr rdr]
+
+-- Couldn't make out how to add New imports by ghc-exactprint;
+-- using direct TextEdit instead.
+hidePreludeSymbol :: DynFlags -> String -> ParsedSource -> TextEdit
+hidePreludeSymbol df symbol (L _ HsModule{..}) =
+    let ran = fromJust $ srcSpanToRange $ getLoc $ last hsmodImports
+        col = ran ^. start.character
+        beg = Position (1 + (ran ^. end.line)) 0
+        symOcc = mkVarOcc symbol
+        symImp = T.pack $ showSDoc df $ parenSymOcc symOcc $ ppr symOcc
+    in TextEdit
+        (Range beg beg)
+      $ T.replicate col " " <> "import Prelude hiding (" <> symImp <> ")\n"
 
 findImportDeclByRange :: [LImportDecl GhcPs] -> Range -> Maybe (LImportDecl GhcPs)
 findImportDeclByRange xs range = find (\(L l _)-> srcSpanToRange l == Just range) xs
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index 1b7c71ad0d..f22ec0bbcf 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}
@@ -6,6 +7,7 @@
 module Development.IDE.Plugin.CodeAction.ExactPrint
   ( Rewrite (..),
     rewriteToEdit,
+    transferAnn,
 
     -- * Utilities
     appendConstraint,
@@ -18,24 +20,28 @@ where
 import Control.Applicative
 import Control.Monad
 import Control.Monad.Trans
+import Data.Char (isAlphaNum)
 import Data.Data (Data)
 import Data.Functor
 import qualified Data.HashMap.Strict as HMap
 import qualified Data.Map.Strict as Map
-import Data.Maybe (fromJust, mapMaybe)
+import Data.Maybe (fromJust, isNothing, mapMaybe)
 import qualified Data.Text as T
 import Development.IDE.GHC.Compat hiding (parseExpr)
 import Development.IDE.GHC.ExactPrint
 import Development.IDE.Types.Location
+import FieldLabel (flLabel)
 import GhcPlugins (realSrcSpanEnd, realSrcSpanStart, sigPrec)
 import Language.Haskell.GHC.ExactPrint
 import Language.Haskell.GHC.ExactPrint.Types (DeltaPos (DP), KeywordId (G), mkAnnKey)
 import Language.Haskell.LSP.Types
 import OccName
 import Outputable (ppr, showSDocUnsafe)
-import Retrie.GHC (unpackFS)
-import FieldLabel (flLabel)
-
+import Retrie.GHC (rdrNameOcc, unpackFS)
+import HeaderInfo (mkPrelImports)
+import Retrie (mkRealSrcSpan)
+import Retrie.GHC (SourceText(NoSourceText))
+import RdrName (mkRdrUnqual)
 ------------------------------------------------------------------------------
 
 -- | Construct a 'Rewrite', replacing the node at the given 'SrcSpan' with the
@@ -330,13 +336,28 @@ extendHiding symbol (L l idecls) mlies df = do
     rdr <- liftParseAST df symbol
     let lie = L src $ IEName rdr
         x = L top $ IEVar noExtField lie
-    when hasSibling $
-      addTrailingCommaT (last lies)
-    addSimpleAnnT x (DP (0, if hasSibling then 1 else 0)) []
-    addSimpleAnnT rdr dp00 $ unqalDP $ hasParen symbol
-    unless hasSibling $ forM_ mlies $ \lies0 ->
-      transferAnn lies0 (L l' [x]) id
-    return $ L l idecls {ideclHiding = Just (True, L l' $ lies ++ [x])}
+        singleHide = L l' [x]
+    when (isNothing mlies) $ do
+        addSimpleAnnT
+            singleHide
+            dp00
+            [ (G AnnHiding, DP (0, 1))
+            , (G AnnOpenP, DP (0, 1))
+            , (G AnnCloseP, DP (0, 0))
+            ]
+    addSimpleAnnT x (DP (0, 0)) []
+    addSimpleAnnT rdr dp00 $ unqalDP $ isOperator $ unLoc rdr
+    if hasSibling
+        then when hasSibling $ do
+            addTrailingCommaT x
+            addSimpleAnnT (head lies) (DP (0, 1)) []
+            unless (null $ tail lies) $
+                addTrailingCommaT (head lies) -- Why we need this?
+        else forM_ mlies $ \lies0 -> do
+            transferAnn lies0 singleHide id
+    return $ L l idecls {ideclHiding = Just (True, L l' $ x : lies)}
+    where
+        isOperator = not . all isAlphaNum . occNameString . rdrNameOcc
 
 deleteFromImport ::
     String ->
@@ -344,7 +365,14 @@ deleteFromImport ::
     Located [LIE GhcPs] ->
     DynFlags ->
     TransformT (Either String) (LImportDecl GhcPs)
-deleteFromImport symbol (L l idecls) (L lieLoc lies) _ =
+deleteFromImport symbol (L l idecls) llies@(L lieLoc lies) _ =do
+    let edited = L lieLoc deletedLies
+    when (not (null lies) && null deletedLies) $ do
+        transferAnn llies edited id
+        addSimpleAnnT edited dp00
+            [(G AnnOpenP, DP (0, 1))
+            ,(G AnnCloseP, DP (0,0))
+            ]
     pure $ L l $ idecls
         { ideclHiding = Just (False, L lieLoc deletedLies)
         }
@@ -352,19 +380,22 @@ deleteFromImport symbol (L l idecls) (L lieLoc lies) _ =
         deletedLies =
             mapMaybe killLie lies
         killLie :: LIE GhcPs -> Maybe (LIE GhcPs)
-        killLie v@(L _ (IEVar _ (L _ (unIEWrappedName -> nam))))
+        killLie v@(L _ (IEVar _ (L _ (rawIEWrapName -> nam))))
             | nam == symbol  = Nothing
             | otherwise = Just v
-        killLie v@(L _ (IEThingAbs _ (L _ (unIEWrappedName -> nam))))
+        killLie v@(L _ (IEThingAbs _ (L _ (rawIEWrapName -> nam))))
             | nam == symbol = Nothing
             | otherwise = Just v
 
-        killLie (L lieL (IEThingWith xt ty@(L _ (unIEWrappedName -> nam)) wild cons flds))
+        killLie (L lieL (IEThingWith xt ty@(L _ (rawIEWrapName -> nam)) wild cons flds))
             | nam == symbol = Nothing
             | otherwise = Just $
                 L lieL $ IEThingWith xt ty wild
-                  (filter ((/= symbol) . unIEWrappedName . unLoc) cons)
+                  (filter ((/= symbol) . rawIEWrapName . unLoc) cons)
                   (filter ((/= symbol) . unpackFS . flLabel . unLoc) flds)
         killLie v = Just v
 
-
+rawIEWrapName :: IEWrappedName RdrName -> String
+rawIEWrapName (IEName (L _ nam)) = occNameString $ rdrNameOcc nam
+rawIEWrapName (IEPattern (L _ nam)) = occNameString $ rdrNameOcc nam
+rawIEWrapName (IEType (L _ nam)) = occNameString $ rdrNameOcc nam

From 65724faa9cc157689bc3289d86004eca05a68c5e Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 22:46:34 +0900
Subject: [PATCH 09/43] Import list reorder

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs            | 5 +++--
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 5 +----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index bf94a4b944..a039dd6681 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -54,13 +54,14 @@ import Ide.PluginUtils (subRange)
 import Ide.Types
 import qualified Language.Haskell.LSP.Core as LSP
 import Language.Haskell.LSP.Types
+import Language.Haskell.LSP.Types.Lens (character, end, line, start)
 import Language.Haskell.LSP.VFS
+import OccName (parenSymOcc)
 import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
 import Retrie.GHC (mkVarOcc)
 import Safe (atMay)
 import Text.Regex.TDFA (mrAfter, (=~), (=~~))
-import Language.Haskell.LSP.Types.Lens (start, character, end, line)
-import OccName (parenSymOcc)
+
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
   (defaultPluginDescriptor plId)
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index f22ec0bbcf..dd96104f20 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -38,10 +38,7 @@ import Language.Haskell.LSP.Types
 import OccName
 import Outputable (ppr, showSDocUnsafe)
 import Retrie.GHC (rdrNameOcc, unpackFS)
-import HeaderInfo (mkPrelImports)
-import Retrie (mkRealSrcSpan)
-import Retrie.GHC (SourceText(NoSourceText))
-import RdrName (mkRdrUnqual)
+
 ------------------------------------------------------------------------------
 
 -- | Construct a 'Rewrite', replacing the node at the given 'SrcSpan' with the

From 4ed8abc2509fef004d31fc198c548248ac74a0a7 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Wed, 27 Jan 2021 22:49:28 +0900
Subject: [PATCH 10/43] Remove redundant fmt

---
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index dd96104f20..db4ee0cd0c 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -1,5 +1,4 @@
 {-# LANGUAGE DerivingStrategies #-}
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}

From 30f2f165d42776c93a9a4b1799a9879207b49c31 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Fri, 29 Jan 2021 10:39:32 +0900
Subject: [PATCH 11/43] lint

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 00dd120c97..4a122c3ed1 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -122,7 +122,7 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
                                 , _documentChanges = Nothing }
                         )
                         (-- either (Left . traceShow) Right $
-                            either (const mempty) id .
+                            fromRight mempty.
                         rewriteToEdit dynflags uri (annsA ps))
                     ) edRewrs
 

From 9e656c5201c1abfec1878d885f3b269880b24db6 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Fri, 29 Jan 2021 10:45:41 +0900
Subject: [PATCH 12/43] Missing import

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 1 +
 1 file changed, 1 insertion(+)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 4a122c3ed1..b894812137 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -61,6 +61,7 @@ import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
 import Retrie.GHC (mkVarOcc)
 import Safe (atMay)
 import Text.Regex.TDFA (mrAfter, (=~), (=~~))
+import Data.Either (fromRight)
 
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =

From d19b4fbf845d8dab919aebbe5641fc6bbcfa5a59 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 00:03:07 +0900
Subject: [PATCH 13/43] Excludes false-positive qualified imports

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 42 ++++++++++++++++++-
 .../IDE/Plugin/CodeAction/ExactPrint.hs       |  1 +
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index b894812137..3f2add02e2 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -62,6 +62,8 @@ import Retrie.GHC (mkVarOcc)
 import Safe (atMay)
 import Text.Regex.TDFA (mrAfter, (=~), (=~~))
 import Data.Either (fromRight)
+import Retrie (unpackFS)
+import FieldLabel (flLabel)
 
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
@@ -753,6 +755,10 @@ data ModuleTarget
     | ImplicitPrelude [LImportDecl GhcPs]
     deriving (Show)
 
+targetImports :: ModuleTarget -> [LImportDecl GhcPs]
+targetImports (ExistingImp ne) = NE.toList ne
+targetImports (ImplicitPrelude xs) = xs
+
 oneAndOthers :: [a] -> [(a, [a])]
 oneAndOthers = go
     where
@@ -811,17 +817,49 @@ suggestImportDisambiguation df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic
                     , L _ qual <- nubOrd $ mapMaybe (ideclAs . unLoc)
                         $ NE.toList imps
                     ]
-                    ++ [ToQualified modName]
+                    ++ [ToQualified modName
+                        | any (occursUnqualified symbol . unLoc)
+                            (targetImports modTarget)
+                        || case modTarget of
+                            ImplicitPrelude{} -> True
+                            _ -> False
+                        ]
                 ]
             | otherwise = []
         renderUniquify HideOthers {} modName symbol =
-            "Use the import from " <> modName <> " for " <> symbol <> ", hiding other imports"
+            "Use " <> modName <> " for " <> symbol <> ", hiding other imports"
         renderUniquify (ToQualified qual) _ symbol =
             "Replace with qualified: "
                 <> T.pack (moduleNameString qual)
                 <> "."
                 <> symbol
 
+occursUnqualified :: T.Text -> ImportDecl GhcPs -> Bool
+occursUnqualified symbol ImportDecl{..}
+    | isNothing ideclAs = Just False /=
+            -- I don't find this particularly comprehensible,
+            -- but HLint suggested me to do so...
+        (ideclHiding <&> \(isHiding, L _ ents) ->
+            let occurs = any ((symbol `symbolOccursIn`) . unLoc) ents
+            in isHiding && not occurs || not isHiding && occurs
+        )
+occursUnqualified _ _ = False
+
+symbolOccursIn :: T.Text -> IE GhcPs -> Bool
+symbolOccursIn symb = \case
+   IEVar _ (L _ n) -> rawIEWrapName n == T.unpack symb
+   IEThingAbs _ (L _ n) -> rawIEWrapName n == T.unpack symb
+   IEThingAll _ (L _ n) -> rawIEWrapName n == T.unpack symb
+   IEThingWith _ (L _ n) _ ents flds ->
+    rawIEWrapName n == T.unpack symb
+    || any ((== T.unpack symb) . rawIEWrapName . unLoc) ents
+    || any ((== T.unpack symb) . unpackFS . flLabel . unLoc) flds
+   IEModuleContents{} -> False
+   IEGroup{} -> False
+   IEDoc{} -> False
+   IEDocNamed{} -> False
+   XIE{} -> False
+
 targetModuleName :: ModuleTarget -> ModuleName
 targetModuleName ImplicitPrelude{} = mkModuleName "Prelude"
 targetModuleName (ExistingImp (L _ ImportDecl{..} :| _)) =
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index db4ee0cd0c..854979e952 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -7,6 +7,7 @@ module Development.IDE.Plugin.CodeAction.ExactPrint
   ( Rewrite (..),
     rewriteToEdit,
     transferAnn,
+    rawIEWrapName,
 
     -- * Utilities
     appendConstraint,

From eb3cd113326ed98887b32d0e9e93083c3c336e48 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 00:04:18 +0900
Subject: [PATCH 14/43] A first test (not enough though)

---
 ghcide/test/data/hiding/AVec.hs               | 17 +++++++++++++
 ghcide/test/data/hiding/BVec.hs               | 17 +++++++++++++
 ghcide/test/data/hiding/CVec.hs               | 17 +++++++++++++
 ghcide/test/data/hiding/DVec.hs               | 17 +++++++++++++
 ghcide/test/data/hiding/EVec.hs               | 17 +++++++++++++
 ghcide/test/data/hiding/HideFunction.hs       | 11 ++++++++
 .../HideFunction.hs.expected.A.fromList       | 11 ++++++++
 ghcide/test/data/hiding/hie.yaml              | 10 ++++++++
 ghcide/test/exe/Main.hs                       | 25 +++++++++++++++++++
 9 files changed, 142 insertions(+)
 create mode 100644 ghcide/test/data/hiding/AVec.hs
 create mode 100644 ghcide/test/data/hiding/BVec.hs
 create mode 100644 ghcide/test/data/hiding/CVec.hs
 create mode 100644 ghcide/test/data/hiding/DVec.hs
 create mode 100644 ghcide/test/data/hiding/EVec.hs
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs.expected.A.fromList
 create mode 100644 ghcide/test/data/hiding/hie.yaml

diff --git a/ghcide/test/data/hiding/AVec.hs b/ghcide/test/data/hiding/AVec.hs
new file mode 100644
index 0000000000..62dee4ca3a
--- /dev/null
+++ b/ghcide/test/data/hiding/AVec.hs
@@ -0,0 +1,17 @@
+module AVec (Vec, (++), cons, fromList, snoc) where
+
+import Prelude hiding ((++))
+
+data Vec a
+
+(++) :: Vec a -> Vec a -> Vec a
+(++) = undefined
+
+fromList :: [a] -> Vec a
+fromList = undefined
+
+cons :: a -> Vec a -> Vec a
+cons = undefined
+
+snoc :: Vec a -> a -> Vec a
+snoc = undefined
diff --git a/ghcide/test/data/hiding/BVec.hs b/ghcide/test/data/hiding/BVec.hs
new file mode 100644
index 0000000000..3f2a1ab259
--- /dev/null
+++ b/ghcide/test/data/hiding/BVec.hs
@@ -0,0 +1,17 @@
+module BVec (Vec, (++), cons, fromList, snoc) where
+
+import Prelude hiding ((++))
+
+data Vec a
+
+(++) :: Vec a -> Vec a -> Vec a
+(++) = undefined
+
+fromList :: [a] -> Vec a
+fromList = undefined
+
+cons :: a -> Vec a -> Vec a
+cons = undefined
+
+snoc :: Vec a -> a -> Vec a
+snoc = undefined
diff --git a/ghcide/test/data/hiding/CVec.hs b/ghcide/test/data/hiding/CVec.hs
new file mode 100644
index 0000000000..b943c786bd
--- /dev/null
+++ b/ghcide/test/data/hiding/CVec.hs
@@ -0,0 +1,17 @@
+module CVec (Vec, (++), cons, fromList, snoc) where
+
+import Prelude hiding ((++))
+
+data Vec a
+
+(++) :: Vec a -> Vec a -> Vec a
+(++) = undefined
+
+fromList :: [a] -> Vec a
+fromList = undefined
+
+cons :: a -> Vec a -> Vec a
+cons = undefined
+
+snoc :: Vec a -> a -> Vec a
+snoc = undefined
diff --git a/ghcide/test/data/hiding/DVec.hs b/ghcide/test/data/hiding/DVec.hs
new file mode 100644
index 0000000000..b293b18176
--- /dev/null
+++ b/ghcide/test/data/hiding/DVec.hs
@@ -0,0 +1,17 @@
+module DVec (Vec, (++), cons, fromList, snoc) where
+
+import Prelude hiding ((++))
+
+data Vec a
+
+(++) :: Vec a -> Vec a -> Vec a
+(++) = undefined
+
+fromList :: [a] -> Vec a
+fromList = undefined
+
+cons :: a -> Vec a -> Vec a
+cons = undefined
+
+snoc :: Vec a -> a -> Vec a
+snoc = undefined
diff --git a/ghcide/test/data/hiding/EVec.hs b/ghcide/test/data/hiding/EVec.hs
new file mode 100644
index 0000000000..456305f915
--- /dev/null
+++ b/ghcide/test/data/hiding/EVec.hs
@@ -0,0 +1,17 @@
+module EVec (Vec, (++), cons, fromList, snoc) where
+
+import Prelude hiding ((++))
+
+data Vec a
+
+(++) :: Vec a -> Vec a -> Vec a
+(++) = undefined
+
+fromList :: [a] -> Vec a
+fromList = undefined
+
+cons :: a -> Vec a -> Vec a
+cons = undefined
+
+snoc :: Vec a -> a -> Vec a
+snoc = undefined
diff --git a/ghcide/test/data/hiding/HideFunction.hs b/ghcide/test/data/hiding/HideFunction.hs
new file mode 100644
index 0000000000..ade8f63ac5
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs
@@ -0,0 +1,11 @@
+module HideFunction where
+
+import AVec (fromList)
+import BVec (fromList, (++))
+import CVec hiding (cons)
+import DVec hiding (cons, snoc)
+import EVec as E
+
+theFun = fromList
+
+theOp = (++)
diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.A.fromList b/ghcide/test/data/hiding/HideFunction.hs.expected.A.fromList
new file mode 100644
index 0000000000..b91d83f98b
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs.expected.A.fromList
@@ -0,0 +1,11 @@
+module HideFunction where
+
+import AVec (fromList)
+import BVec ( (++))
+import CVec hiding (fromList, cons)
+import DVec hiding (fromList, cons, snoc)
+import EVec as E hiding (fromList)
+
+theFun = fromList
+
+theOp = (++)
diff --git a/ghcide/test/data/hiding/hie.yaml b/ghcide/test/data/hiding/hie.yaml
new file mode 100644
index 0000000000..075686555e
--- /dev/null
+++ b/ghcide/test/data/hiding/hie.yaml
@@ -0,0 +1,10 @@
+cradle:
+    direct:
+        arguments:
+        - -Wall
+        - HideFunction.hs
+        - AVec.hs
+        - BVec.hs
+        - CVec.hs
+        - DVec.hs
+        - EVec.hs
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index d124a5e77f..b9dfd09728 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -27,6 +27,7 @@ import Development.IDE.Core.PositionMapping (fromCurrent, toCurrent, PositionRes
 import Development.IDE.Core.Shake (Q(..))
 import Development.IDE.GHC.Util
 import qualified Data.Text as T
+import qualified Data.Text.IO as T
 import Data.Typeable
 import Development.IDE.Plugin.TypeLenses (typeLensCommandId)
 import Development.IDE.Spans.Common
@@ -678,6 +679,7 @@ codeActionTests = testGroup "code actions"
   , removeImportTests
   , extendImportTests
   , suggestImportTests
+  , suggestImportDisambiguationTests
   , disableWarningTests
   , fixConstructorImportTests
   , importRenameActionTests
@@ -1460,6 +1462,29 @@ suggestImportTests = testGroup "suggest import actions"
           else
               liftIO $ [_title | CACodeAction CodeAction{_title} <- actions, _title == newImp ] @?= []
 
+suggestImportDisambiguationTests :: TestTree
+suggestImportDisambiguationTests = testGroup "suggest import disambiguation actions"
+  [ testGroup "Hiding strategy works"
+    [ testCase "Symbol" $ runInDir hidingDir $ do
+        doc <- openDoc ("HideFunction" <.> "hs") "haskell"
+        expected <- liftIO $
+            T.readFile (hidingDir </> "HideFunction" <.> "hs" <.> "expected.A.fromList")
+        void (skipManyTill anyMessage message
+            :: Session WorkDoneProgressEndNotification)
+        void waitForDiagnostics
+        liftIO $ sleep 0.5
+        contents <- documentContents doc
+        let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
+        actions <- getCodeActions doc range
+        action <- liftIO $ pickActionWithTitle "Use AVec for fromList, hiding other imports" actions
+        executeCodeAction action
+        contentAfterAction <- documentContents doc
+        liftIO $ expected @=? contentAfterAction
+    ]
+  ]
+  where
+    hidingDir = "test/data/hiding"
+
 disableWarningTests :: TestTree
 disableWarningTests =
   testGroup "disable warnings" $

From 0239aa0e718bb1f279ca38681bcea2a20d58987b Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 00:09:26 +0900
Subject: [PATCH 15/43] fmt.sh

---
 ghcide/test/exe/Main.hs | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index b9dfd09728..4fec418940 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -27,11 +27,20 @@ import Development.IDE.Core.PositionMapping (fromCurrent, toCurrent, PositionRes
 import Development.IDE.Core.Shake (Q(..))
 import Development.IDE.GHC.Util
 import qualified Data.Text as T
-import qualified Data.Text.IO as T
 import Data.Typeable
 import Development.IDE.Plugin.TypeLenses (typeLensCommandId)
 import Development.IDE.Spans.Common
 import Development.IDE.Test
+    ( canonicalizeUri,
+      diagnostic,
+      expectCurrentDiagnostics,
+      expectDiagnostics,
+      expectDiagnosticsWithTags,
+      expectNoMoreDiagnostics,
+      flushMessages,
+      standardizeQuotes,
+      waitForAction,
+      Cursor )
 import Development.IDE.Test.Runfiles
 import qualified Development.IDE.Types.Diagnostics as Diagnostics
 import Development.IDE.Types.Location
@@ -1465,10 +1474,21 @@ suggestImportTests = testGroup "suggest import actions"
 suggestImportDisambiguationTests :: TestTree
 suggestImportDisambiguationTests = testGroup "suggest import disambiguation actions"
   [ testGroup "Hiding strategy works"
-    [ testCase "Symbol" $ runInDir hidingDir $ do
+    [ testGroup "fromList"
+        [ testCase "AVec" $ withHideFunction $ \doc actions -> do
+            expected <- liftIO $
+                readFileUtf8 (hidingDir </> "HideFunction" <.> "hs" <.> "expected.A.fromList")
+            action <- liftIO $ pickActionWithTitle "Use AVec for fromList, hiding other imports" actions
+            executeCodeAction action
+            contentAfterAction <- documentContents doc
+            liftIO $ expected @=? contentAfterAction
+        ]
+    ]
+  ]
+  where
+    hidingDir = "test/data/hiding"
+    withHideFunction k = runInDir hidingDir $ do
         doc <- openDoc ("HideFunction" <.> "hs") "haskell"
-        expected <- liftIO $
-            T.readFile (hidingDir </> "HideFunction" <.> "hs" <.> "expected.A.fromList")
         void (skipManyTill anyMessage message
             :: Session WorkDoneProgressEndNotification)
         void waitForDiagnostics
@@ -1476,14 +1496,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
         contents <- documentContents doc
         let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
         actions <- getCodeActions doc range
-        action <- liftIO $ pickActionWithTitle "Use AVec for fromList, hiding other imports" actions
-        executeCodeAction action
-        contentAfterAction <- documentContents doc
-        liftIO $ expected @=? contentAfterAction
-    ]
-  ]
-  where
-    hidingDir = "test/data/hiding"
+        k doc actions
 
 disableWarningTests :: TestTree
 disableWarningTests =
@@ -2911,7 +2924,7 @@ findDefinitionAndHoverTests = let
         Position{_line = l + 1, _character = c + 1}
     in
     case map (read . T.unpack) lineCol of
-      [l,c] -> liftIO $ (adjust $ _start expectedRange) @=? Position l c
+      [l,c] -> liftIO $ adjust (_start expectedRange) @=? Position l c
       _     -> liftIO $ assertFailure $
         "expected: " <> show ("[...]" <> sourceFileName <> ":<LINE>:<COL>**[...]", Just expectedRange) <>
         "\n but got: " <> show (msg, rangeInHover)

From a6ddab25b4876f94eacac6b04211a9e3989d352a Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 00:33:02 +0900
Subject: [PATCH 16/43] Some more test cases

---
 .../hiding/HideFunction.hs.expected.append.E  | 12 ++++++
 ...st => HideFunction.hs.expected.fromList.A} |  0
 ghcide/test/exe/Main.hs                       | 41 +++++++++++++++----
 3 files changed, 46 insertions(+), 7 deletions(-)
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs.expected.append.E
 rename ghcide/test/data/hiding/{HideFunction.hs.expected.A.fromList => HideFunction.hs.expected.fromList.A} (100%)

diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.append.E b/ghcide/test/data/hiding/HideFunction.hs.expected.append.E
new file mode 100644
index 0000000000..94d333b24a
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs.expected.append.E
@@ -0,0 +1,12 @@
+module HideFunction where
+
+import AVec (fromList)
+import BVec (fromList,)
+import CVec hiding ((++), cons)
+import DVec hiding ((++), cons, snoc)
+import EVec as E
+import Prelude hiding ((++))
+
+theFun = fromList
+
+theOp = (++)
diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.A.fromList b/ghcide/test/data/hiding/HideFunction.hs.expected.fromList.A
similarity index 100%
rename from ghcide/test/data/hiding/HideFunction.hs.expected.A.fromList
rename to ghcide/test/data/hiding/HideFunction.hs.expected.fromList.A
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 4fec418940..a9eac281d5 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1475,18 +1475,45 @@ suggestImportDisambiguationTests :: TestTree
 suggestImportDisambiguationTests = testGroup "suggest import disambiguation actions"
   [ testGroup "Hiding strategy works"
     [ testGroup "fromList"
-        [ testCase "AVec" $ withHideFunction $ \doc actions -> do
-            expected <- liftIO $
-                readFileUtf8 (hidingDir </> "HideFunction" <.> "hs" <.> "expected.A.fromList")
-            action <- liftIO $ pickActionWithTitle "Use AVec for fromList, hiding other imports" actions
-            executeCodeAction action
-            contentAfterAction <- documentContents doc
-            liftIO $ expected @=? contentAfterAction
+        [ testCase "AVec" $
+            compareHideFunctionTo
+                "Use AVec for fromList, hiding other imports"
+                "HideFunction.hs.expected.fromList.A"
+        ]
+    , testGroup "(++)"
+        [testCase "EVec" $
+            compareHideFunctionTo
+                "Use EVec for ++, hiding other imports"
+                "HideFunction.hs.expected.append.E"
         ]
     ]
+  , testGroup "Qualify strategy"
+    [ testCase "won't suggest full name for qualified module" $
+      withHideFunction $ \_ actions -> do
+        liftIO $
+            assertBool "EVec.fromList must not be suggested" $
+                "Replace with qualified: EVec.fromList" `notElem`
+                [ actionTitle
+                | CACodeAction CodeAction { _title = actionTitle } <- actions
+                ]
+        liftIO $
+            assertBool "EVec.++ must not be suggested" $
+                "Replace with qualified: EVec.++" `notElem`
+                [ actionTitle
+                | CACodeAction CodeAction { _title = actionTitle } <- actions
+                ]
+    ]
   ]
   where
     hidingDir = "test/data/hiding"
+    compareHideFunctionTo cmd expected =
+        withHideFunction $ \doc actions -> do
+            expected <- liftIO $
+                readFileUtf8 (hidingDir </> expected)
+            action <- liftIO $ pickActionWithTitle cmd actions
+            executeCodeAction action
+            contentAfterAction <- documentContents doc
+            liftIO $ expected @=? contentAfterAction
     withHideFunction k = runInDir hidingDir $ do
         doc <- openDoc ("HideFunction" <.> "hs") "haskell"
         void (skipManyTill anyMessage message

From 4816c8455000d2f5d74bdc513fdb2f87b58af922 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 01:05:26 +0900
Subject: [PATCH 17/43] More test cases

---
 .../IDE/Plugin/CodeAction/ExactPrint.hs         | 10 ++++++----
 .../hiding/HideFunction.hs.expected.fromList.B  | 11 +++++++++++
 ...unction.hs.expected.qualified.append.Prelude | 11 +++++++++++
 ...ideFunction.hs.expected.qualified.fromList.E | 11 +++++++++++
 ghcide/test/exe/Main.hs                         | 17 +++++++++++++++++
 5 files changed, 56 insertions(+), 4 deletions(-)
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs.expected.fromList.B
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs.expected.qualified.append.Prelude
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs.expected.qualified.fromList.E

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index 854979e952..fbf9d43c97 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -362,17 +362,18 @@ deleteFromImport ::
     Located [LIE GhcPs] ->
     DynFlags ->
     TransformT (Either String) (LImportDecl GhcPs)
-deleteFromImport symbol (L l idecls) llies@(L lieLoc lies) _ =do
+deleteFromImport symbol (L l idecl) llies@(L lieLoc lies) _ =do
     let edited = L lieLoc deletedLies
+        lidecl' = L l $ idecl
+            { ideclHiding = Just (False, edited)
+            }
     when (not (null lies) && null deletedLies) $ do
         transferAnn llies edited id
         addSimpleAnnT edited dp00
             [(G AnnOpenP, DP (0, 1))
             ,(G AnnCloseP, DP (0,0))
             ]
-    pure $ L l $ idecls
-        { ideclHiding = Just (False, L lieLoc deletedLies)
-        }
+    pure lidecl'
     where
         deletedLies =
             mapMaybe killLie lies
@@ -392,6 +393,7 @@ deleteFromImport symbol (L l idecls) llies@(L lieLoc lies) _ =do
                   (filter ((/= symbol) . unpackFS . flLabel . unLoc) flds)
         killLie v = Just v
 
+-- This must not belong here?
 rawIEWrapName :: IEWrappedName RdrName -> String
 rawIEWrapName (IEName (L _ nam)) = occNameString $ rdrNameOcc nam
 rawIEWrapName (IEPattern (L _ nam)) = occNameString $ rdrNameOcc nam
diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.fromList.B b/ghcide/test/data/hiding/HideFunction.hs.expected.fromList.B
new file mode 100644
index 0000000000..e131d86c1c
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs.expected.fromList.B
@@ -0,0 +1,11 @@
+module HideFunction where
+
+import AVec ()
+import BVec (fromList, (++))
+import CVec hiding (fromList, cons)
+import DVec hiding (fromList, cons, snoc)
+import EVec as E hiding (fromList)
+
+theFun = fromList
+
+theOp = (++)
diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.qualified.append.Prelude b/ghcide/test/data/hiding/HideFunction.hs.expected.qualified.append.Prelude
new file mode 100644
index 0000000000..505125f55a
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs.expected.qualified.append.Prelude
@@ -0,0 +1,11 @@
+module HideFunction where
+
+import AVec (fromList)
+import BVec (fromList, (++))
+import CVec hiding (cons)
+import DVec hiding (cons, snoc)
+import EVec as E
+
+theFun = fromList
+
+theOp = (Prelude.++)
diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.qualified.fromList.E b/ghcide/test/data/hiding/HideFunction.hs.expected.qualified.fromList.E
new file mode 100644
index 0000000000..e81909ce0f
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs.expected.qualified.fromList.E
@@ -0,0 +1,11 @@
+module HideFunction where
+
+import AVec (fromList)
+import BVec (fromList, (++))
+import CVec hiding (cons)
+import DVec hiding (cons, snoc)
+import EVec as E
+
+theFun = E.fromList
+
+theOp = (++)
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index a9eac281d5..45fe975d1b 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1479,6 +1479,11 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             compareHideFunctionTo
                 "Use AVec for fromList, hiding other imports"
                 "HideFunction.hs.expected.fromList.A"
+        , expectFailBecause "Known bug - Modifying topmost import decl adds additional newline at the top"
+        $  testCase "BVec" $
+            compareHideFunctionTo
+                "Use BVec for fromList, hiding other imports"
+                "HideFunction.hs.expected.fromList.B"
         ]
     , testGroup "(++)"
         [testCase "EVec" $
@@ -1502,6 +1507,18 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
                 [ actionTitle
                 | CACodeAction CodeAction { _title = actionTitle } <- actions
                 ]
+    , testGroup "fromList"
+        [ testCase "EVec" $
+            compareHideFunctionTo
+                "Replace with qualified: E.fromList"
+                "HideFunction.hs.expected.qualified.fromList.E"
+        ]
+    , testGroup "(++)"
+        [ testCase "Prelude" $
+            compareHideFunctionTo
+                "Replace with qualified: Prelude.++"
+                "HideFunction.hs.expected.qualified.append.Prelude"
+        ]
     ]
   ]
   where

From 3b6c048c393d5504f4c4898a01d4ab8e2b170668 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 01:27:35 +0900
Subject: [PATCH 18/43] Ah! CRLF have bitten me!

---
 ghcide/test/exe/Main.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 45fe975d1b..71f18b1cac 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1530,7 +1530,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             action <- liftIO $ pickActionWithTitle cmd actions
             executeCodeAction action
             contentAfterAction <- documentContents doc
-            liftIO $ expected @=? contentAfterAction
+            liftIO $ T.replace "\r\n" "\n" expected @=? contentAfterAction
     withHideFunction k = runInDir hidingDir $ do
         doc <- openDoc ("HideFunction" <.> "hs") "haskell"
         void (skipManyTill anyMessage message

From dff4d035b4c59351d427c0e8436a40d330c81139 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 17:31:57 +0900
Subject: [PATCH 19/43] Tentative workaround for #1274

---
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 7 ++++++-
 ghcide/test/exe/Main.hs                                    | 3 +--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index fbf9d43c97..d22c01893a 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -29,6 +29,7 @@ import Data.Maybe (fromJust, isNothing, mapMaybe)
 import qualified Data.Text as T
 import Development.IDE.GHC.Compat hiding (parseExpr)
 import Development.IDE.GHC.ExactPrint
+    ( Annotate, ASTElement(parseAST) )
 import Development.IDE.Types.Location
 import FieldLabel (flLabel)
 import GhcPlugins (realSrcSpanEnd, realSrcSpanStart, sigPrec)
@@ -68,12 +69,16 @@ rewriteToEdit dflags uri anns (Rewrite dst f) = do
           [ ( uri,
               List
                 [ TextEdit (fromJust $ srcSpanToRange dst) $
-                    T.pack $ tail $ exactPrint ast anns
+                    stripPrecedingNewline $ T.pack $ tail $ exactPrint ast anns
                 ]
             )
           ]
   pure $ WorkspaceEdit (Just editMap) Nothing
 
+stripPrecedingNewline
+    :: T.Text -> T.Text
+stripPrecedingNewline = T.dropWhile (`elem` ("\r\n" :: [Char]))
+
 srcSpanToRange :: SrcSpan -> Maybe Range
 srcSpanToRange (UnhelpfulSpan _) = Nothing
 srcSpanToRange (RealSrcSpan real) = Just $ realSrcSpanToRange real
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 71f18b1cac..c7dd2ba9da 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1479,8 +1479,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             compareHideFunctionTo
                 "Use AVec for fromList, hiding other imports"
                 "HideFunction.hs.expected.fromList.A"
-        , expectFailBecause "Known bug - Modifying topmost import decl adds additional newline at the top"
-        $  testCase "BVec" $
+        , testCase "BVec" $
             compareHideFunctionTo
                 "Use BVec for fromList, hiding other imports"
                 "HideFunction.hs.expected.fromList.B"

From 0696e5a8e5f0e506ff8eec6cbb7381bf425cbf80 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 17:53:41 +0900
Subject: [PATCH 20/43] Wait much to ensure rewrite suggestion to be collected

---
 ghcide/test/exe/Main.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index c7dd2ba9da..284a1eb0f5 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1535,7 +1535,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
         void (skipManyTill anyMessage message
             :: Session WorkDoneProgressEndNotification)
         void waitForDiagnostics
-        liftIO $ sleep 0.5
+        liftIO $ sleep 1.0
         contents <- documentContents doc
         let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
         actions <- getCodeActions doc range

From c2907ddea4fc752b9a3bef589333b8478a6a1a2d Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 17:54:01 +0900
Subject: [PATCH 21/43] Tests for type suggestion

---
 ghcide/test/data/hiding/AVec.hs               |  5 ++++-
 ghcide/test/data/hiding/BVec.hs               |  5 ++++-
 ghcide/test/data/hiding/CVec.hs               |  5 ++++-
 ghcide/test/data/hiding/DVec.hs               |  5 ++++-
 ghcide/test/data/hiding/EVec.hs               |  5 ++++-
 ghcide/test/data/hiding/HideType.hs           |  9 ++++++++
 .../test/data/hiding/HideType.hs.expected.A   |  9 ++++++++
 .../test/data/hiding/HideType.hs.expected.E   |  9 ++++++++
 ghcide/test/exe/Main.hs                       | 22 +++++++++++++++----
 9 files changed, 65 insertions(+), 9 deletions(-)
 create mode 100644 ghcide/test/data/hiding/HideType.hs
 create mode 100644 ghcide/test/data/hiding/HideType.hs.expected.A
 create mode 100644 ghcide/test/data/hiding/HideType.hs.expected.E

diff --git a/ghcide/test/data/hiding/AVec.hs b/ghcide/test/data/hiding/AVec.hs
index 62dee4ca3a..4c1ea30874 100644
--- a/ghcide/test/data/hiding/AVec.hs
+++ b/ghcide/test/data/hiding/AVec.hs
@@ -1,4 +1,5 @@
-module AVec (Vec, (++), cons, fromList, snoc) where
+{-# LANGUAGE TypeOperators #-}
+module AVec (Vec, type (@@@), (++), cons, fromList, snoc) where
 
 import Prelude hiding ((++))
 
@@ -7,6 +8,8 @@ data Vec a
 (++) :: Vec a -> Vec a -> Vec a
 (++) = undefined
 
+data (@@@) a b
+
 fromList :: [a] -> Vec a
 fromList = undefined
 
diff --git a/ghcide/test/data/hiding/BVec.hs b/ghcide/test/data/hiding/BVec.hs
index 3f2a1ab259..e086bb6ff4 100644
--- a/ghcide/test/data/hiding/BVec.hs
+++ b/ghcide/test/data/hiding/BVec.hs
@@ -1,4 +1,5 @@
-module BVec (Vec, (++), cons, fromList, snoc) where
+{-# LANGUAGE TypeOperators #-}
+module BVec (Vec, type (@@@), (++), cons, fromList, snoc) where
 
 import Prelude hiding ((++))
 
@@ -7,6 +8,8 @@ data Vec a
 (++) :: Vec a -> Vec a -> Vec a
 (++) = undefined
 
+data (@@@) a b
+
 fromList :: [a] -> Vec a
 fromList = undefined
 
diff --git a/ghcide/test/data/hiding/CVec.hs b/ghcide/test/data/hiding/CVec.hs
index b943c786bd..4a5fd3e7e9 100644
--- a/ghcide/test/data/hiding/CVec.hs
+++ b/ghcide/test/data/hiding/CVec.hs
@@ -1,4 +1,5 @@
-module CVec (Vec, (++), cons, fromList, snoc) where
+{-# LANGUAGE TypeOperators #-}
+module CVec (Vec, type (@@@), (++), cons, fromList, snoc) where
 
 import Prelude hiding ((++))
 
@@ -7,6 +8,8 @@ data Vec a
 (++) :: Vec a -> Vec a -> Vec a
 (++) = undefined
 
+data (@@@) a b
+
 fromList :: [a] -> Vec a
 fromList = undefined
 
diff --git a/ghcide/test/data/hiding/DVec.hs b/ghcide/test/data/hiding/DVec.hs
index b293b18176..a580ca907d 100644
--- a/ghcide/test/data/hiding/DVec.hs
+++ b/ghcide/test/data/hiding/DVec.hs
@@ -1,4 +1,5 @@
-module DVec (Vec, (++), cons, fromList, snoc) where
+{-# LANGUAGE TypeOperators #-}
+module DVec (Vec, (++), type (@@@), cons, fromList, snoc) where
 
 import Prelude hiding ((++))
 
@@ -7,6 +8,8 @@ data Vec a
 (++) :: Vec a -> Vec a -> Vec a
 (++) = undefined
 
+data (@@@) a b
+
 fromList :: [a] -> Vec a
 fromList = undefined
 
diff --git a/ghcide/test/data/hiding/EVec.hs b/ghcide/test/data/hiding/EVec.hs
index 456305f915..f5e0b2c269 100644
--- a/ghcide/test/data/hiding/EVec.hs
+++ b/ghcide/test/data/hiding/EVec.hs
@@ -1,4 +1,5 @@
-module EVec (Vec, (++), cons, fromList, snoc) where
+{-# LANGUAGE TypeOperators #-}
+module EVec (Vec, (++), type (@@@), cons, fromList, snoc) where
 
 import Prelude hiding ((++))
 
@@ -7,6 +8,8 @@ data Vec a
 (++) :: Vec a -> Vec a -> Vec a
 (++) = undefined
 
+data (@@@) a b
+
 fromList :: [a] -> Vec a
 fromList = undefined
 
diff --git a/ghcide/test/data/hiding/HideType.hs b/ghcide/test/data/hiding/HideType.hs
new file mode 100644
index 0000000000..926cedf15d
--- /dev/null
+++ b/ghcide/test/data/hiding/HideType.hs
@@ -0,0 +1,9 @@
+module HideType where
+
+import AVec (Vec, fromList)
+import BVec (fromList, (++))
+import CVec hiding (cons)
+import DVec hiding (cons, snoc)
+import EVec as E
+
+type TheType = Vec
diff --git a/ghcide/test/data/hiding/HideType.hs.expected.A b/ghcide/test/data/hiding/HideType.hs.expected.A
new file mode 100644
index 0000000000..a59de871b4
--- /dev/null
+++ b/ghcide/test/data/hiding/HideType.hs.expected.A
@@ -0,0 +1,9 @@
+module HideType where
+
+import AVec (Vec, fromList)
+import BVec (fromList, (++))
+import CVec hiding (Vec, cons)
+import DVec hiding (Vec, cons, snoc)
+import EVec as E hiding (Vec)
+
+type TheType = Vec
diff --git a/ghcide/test/data/hiding/HideType.hs.expected.E b/ghcide/test/data/hiding/HideType.hs.expected.E
new file mode 100644
index 0000000000..51fa6610b5
--- /dev/null
+++ b/ghcide/test/data/hiding/HideType.hs.expected.E
@@ -0,0 +1,9 @@
+module HideType where
+
+import AVec ( fromList)
+import BVec (fromList, (++))
+import CVec hiding (Vec, cons)
+import DVec hiding (Vec, cons, snoc)
+import EVec as E
+
+type TheType = Vec
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 284a1eb0f5..6ad2ee5735 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1490,6 +1490,18 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
                 "Use EVec for ++, hiding other imports"
                 "HideFunction.hs.expected.append.E"
         ]
+    , testGroup "Vec (type)"
+        [ testCase "AVec" $
+            compareTwo
+                "HideType.hs"
+                "Use AVec for Vec, hiding other imports"
+                "HideType.hs.expected.A"
+        , testCase "EVec" $
+            compareTwo
+                "HideType.hs"
+                "Use EVec for Vec, hiding other imports"
+                "HideType.hs.expected.E"
+        ]
     ]
   , testGroup "Qualify strategy"
     [ testCase "won't suggest full name for qualified module" $
@@ -1522,16 +1534,17 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
   ]
   where
     hidingDir = "test/data/hiding"
-    compareHideFunctionTo cmd expected =
-        withHideFunction $ \doc actions -> do
+    compareTwo original cmd expected =
+        withTarget original $ \doc actions -> do
             expected <- liftIO $
                 readFileUtf8 (hidingDir </> expected)
             action <- liftIO $ pickActionWithTitle cmd actions
             executeCodeAction action
             contentAfterAction <- documentContents doc
             liftIO $ T.replace "\r\n" "\n" expected @=? contentAfterAction
-    withHideFunction k = runInDir hidingDir $ do
-        doc <- openDoc ("HideFunction" <.> "hs") "haskell"
+    compareHideFunctionTo = compareTwo "HideFunction.hs"
+    withTarget file k = runInDir hidingDir $ do
+        doc <- openDoc file "haskell"
         void (skipManyTill anyMessage message
             :: Session WorkDoneProgressEndNotification)
         void waitForDiagnostics
@@ -1540,6 +1553,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
         let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
         actions <- getCodeActions doc range
         k doc actions
+    withHideFunction = withTarget ("HideFunction" <.> "hs")
 
 disableWarningTests :: TestTree
 disableWarningTests =

From 41d6c75bfd3e1e87d339fb3f8820ac9a1515defc Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 18:56:18 +0900
Subject: [PATCH 22/43] Slightly more wait

---
 ghcide/test/exe/Main.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 6ad2ee5735..3022c6506e 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1548,7 +1548,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
         void (skipManyTill anyMessage message
             :: Session WorkDoneProgressEndNotification)
         void waitForDiagnostics
-        liftIO $ sleep 1.0
+        liftIO $ sleep 1.5
         contents <- documentContents doc
         let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
         actions <- getCodeActions doc range

From 223808be1f0d015d346a5a5fc38b3dbcb2ea636e Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 20:20:39 +0900
Subject: [PATCH 23/43] A little smarter waiting strartegy for actions

---
 ghcide/test/exe/Main.hs | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 3022c6506e..21adda5296 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -76,6 +76,7 @@ import Control.Monad.Extra (whenJust)
 import qualified Language.Haskell.LSP.Types.Lens as L
 import Control.Lens ((^.))
 import Data.Functor
+import Numeric.Natural (Natural)
 
 main :: IO ()
 main = do
@@ -1548,13 +1549,29 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
         void (skipManyTill anyMessage message
             :: Session WorkDoneProgressEndNotification)
         void waitForDiagnostics
-        liftIO $ sleep 1.5
         contents <- documentContents doc
         let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
-        actions <- getCodeActions doc range
+        actions <- waitForAtLeatOneAction 0.5 4 doc range
         k doc actions
     withHideFunction = withTarget ("HideFunction" <.> "hs")
 
+waitForAtLeatOneAction ::
+    -- | Waiting interval
+    Double ->
+    -- | Maximum # of retry (0 for no retry at ll)
+    Natural ->
+    TextDocumentIdentifier ->
+    Range ->
+    Session [CAResult]
+waitForAtLeatOneAction wait count doc range = go count []
+    where
+        go !remain !acc = do
+            liftIO $ sleep wait
+            actions <- getCodeActions doc range
+            if not (null actions) || remain <= 0
+                then pure $ acc ++ actions
+                else go (remain - 1) (acc ++ actions)
+
 disableWarningTests :: TestTree
 disableWarningTests =
   testGroup "disable warnings" $

From 0721ef9be0cbb72f407bece59019b6ec2dd3ffe5 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 21:57:59 +0900
Subject: [PATCH 24/43] Import list slim up

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 71 +++++++++----------
 1 file changed, 34 insertions(+), 37 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 3f2add02e2..f189d970fe 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -13,34 +13,14 @@ module Development.IDE.Plugin.CodeAction
     , matchRegExMultipleImports
     ) where
 
-import Bag (isEmptyBag)
-import Control.Applicative ((<|>))
-import Control.Arrow (second, (>>>))
-import Control.Concurrent.Extra (readVar)
-import Control.Lens (foldMapBy, (^.))
-import Control.Monad (guard, join)
-import Data.Char
-import Data.Coerce (coerce)
-import qualified Data.DList as DL
-import Data.Function
-import Data.Functor
-import qualified Data.HashMap.Strict as Map
-import qualified Data.HashSet as Set
-import Data.Hashable (Hashable)
-import Data.List.Extra
-import Data.List.NonEmpty (NonEmpty ((:|)))
-import qualified Data.List.NonEmpty as NE
-import Data.Maybe
-import qualified Data.Rope.UTF16 as Rope
-import qualified Data.Text as T
-import Development.IDE.Core.RuleTypes
+import Control.Monad (join, guard)
+import Development.IDE.GHC.Compat
 import Development.IDE.Core.Rules
+import Development.IDE.Core.RuleTypes
 import Development.IDE.Core.Service
 import Development.IDE.Core.Shake
-import Development.IDE.GHC.Compat
 import Development.IDE.GHC.Error
 import Development.IDE.GHC.ExactPrint
-import Development.IDE.GHC.Util (printRdrName)
 import Development.IDE.Plugin.CodeAction.ExactPrint
 import Development.IDE.Plugin.CodeAction.PositionIndexed
 import Development.IDE.Plugin.CodeAction.RuleTypes
@@ -49,21 +29,38 @@ import Development.IDE.Plugin.TypeLenses (suggestSignature)
 import Development.IDE.Types.Exports
 import Development.IDE.Types.Location
 import Development.IDE.Types.Options
-import qualified GHC.LanguageExtensions as Lang
-import Ide.PluginUtils (subRange)
-import Ide.Types
+import qualified Data.HashMap.Strict as Map
 import qualified Language.Haskell.LSP.Core as LSP
-import Language.Haskell.LSP.Types
-import Language.Haskell.LSP.Types.Lens (character, end, line, start)
 import Language.Haskell.LSP.VFS
-import OccName (parenSymOcc)
+import Language.Haskell.LSP.Types
+import qualified Data.Rope.UTF16 as Rope
+import Data.Char
+import Data.Maybe
+import Data.List.Extra
+import Data.List.NonEmpty (NonEmpty((:|)))
+import qualified Data.List.NonEmpty as NE
+import qualified Data.Text as T
+import Text.Regex.TDFA (mrAfter, (=~), (=~~))
 import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
-import Retrie.GHC (mkVarOcc)
+import Data.Function
+import Data.Functor
+import Control.Applicative ((<|>))
 import Safe (atMay)
-import Text.Regex.TDFA (mrAfter, (=~), (=~~))
+import Bag (isEmptyBag)
+import qualified Data.HashSet as Set
+import Control.Concurrent.Extra (readVar)
+import Development.IDE.GHC.Util (printRdrName)
+import Ide.PluginUtils (subRange)
+import Ide.Types
+import Data.Hashable (Hashable)
+import qualified Data.DList as DL
+import Development.IDE.Spans.Common
+import OccName
+import Data.Coerce
 import Data.Either (fromRight)
-import Retrie (unpackFS)
-import FieldLabel (flLabel)
+import Control.Arrow
+import qualified GHC.LanguageExtensions as Lang
+import Control.Lens (foldMapBy)
 
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
@@ -852,8 +849,8 @@ symbolOccursIn symb = \case
    IEThingAll _ (L _ n) -> rawIEWrapName n == T.unpack symb
    IEThingWith _ (L _ n) _ ents flds ->
     rawIEWrapName n == T.unpack symb
-    || any ((== T.unpack symb) . rawIEWrapName . unLoc) ents
-    || any ((== T.unpack symb) . unpackFS . flLabel . unLoc) flds
+    || any ((== symb) . showNameWithoutUniques . unLoc) ents
+    || any ((== symb) . showNameWithoutUniques . unLoc) flds
    IEModuleContents{} -> False
    IEGroup{} -> False
    IEDoc{} -> False
@@ -899,8 +896,8 @@ disambiguateSymbol df pm Diagnostic {..} (T.unpack -> symbol) = \case
 hidePreludeSymbol :: DynFlags -> String -> ParsedSource -> TextEdit
 hidePreludeSymbol df symbol (L _ HsModule{..}) =
     let ran = fromJust $ srcSpanToRange $ getLoc $ last hsmodImports
-        col = ran ^. start.character
-        beg = Position (1 + (ran ^. end.line)) 0
+        col = _character $ _start ran
+        beg = Position (1 + _line (_end ran)) 0
         symOcc = mkVarOcc symbol
         symImp = T.pack $ showSDoc df $ parenSymOcc symOcc $ ppr symOcc
     in TextEdit

From 748744658564d7f2afdff9889dade14a9b95ecc6 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 21:59:05 +0900
Subject: [PATCH 25/43] Adjusted to the master

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index f189d970fe..12475a1535 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -43,6 +43,7 @@ import qualified Data.Text as T
 import Text.Regex.TDFA (mrAfter, (=~), (=~~))
 import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
 import Data.Function
+import Control.Arrow ((>>>), second)
 import Data.Functor
 import Control.Applicative ((<|>))
 import Safe (atMay)
@@ -58,7 +59,6 @@ import Development.IDE.Spans.Common
 import OccName
 import Data.Coerce
 import Data.Either (fromRight)
-import Control.Arrow
 import qualified GHC.LanguageExtensions as Lang
 import Control.Lens (foldMapBy)
 

From b5b7f03f784922a1aa6af0c5d0712db4fd6ee105 Mon Sep 17 00:00:00 2001
From: Hiromi Ishii <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 22:08:56 +0900
Subject: [PATCH 26/43] Update ghcide/src/Development/IDE/Plugin/CodeAction.hs

Co-authored-by: Pepe Iborra <pepeiborra@me.com>
---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 12475a1535..45dc2a7d65 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -136,10 +136,11 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
 -- | Semigroup instance just overrides duplicated keys in the first argument
 unionWSEdit :: WorkspaceEdit -> WorkspaceEdit -> WorkspaceEdit
 unionWSEdit (WorkspaceEdit a b) (WorkspaceEdit c d) =
-    -- FIXME: Want to use monoidal-containers, but it supports aeson <1.5 only...
     WorkspaceEdit (runCatHashMap <$> fmap CatHashMap a <> fmap CatHashMap c)
         (b <> d)
 
+-- | A monoidal hashmap
+     -- FIXME: Want to use monoidal-containers, but it supports aeson <1.5 only...
 newtype CatHashMap k v = CatHashMap { runCatHashMap :: Map.HashMap k v }
 instance (Eq k, Hashable k, Semigroup v) => Semigroup (CatHashMap k v) where
   (<>) = coerce $ Map.unionWith @k @v (<>)

From d4075dc9a529e7ae7d74e847d4dc283499cccae1 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 22:37:39 +0900
Subject: [PATCH 27/43] Rewrote using `expectDiagnostics`

---
 ghcide/test/exe/Main.hs | 47 ++++++++++++++---------------------------
 1 file changed, 16 insertions(+), 31 deletions(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 55c61b56f4..1b025316cb 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -78,7 +78,6 @@ import Control.Monad.Extra (whenJust)
 import qualified Language.Haskell.LSP.Types.Lens as L
 import Control.Lens ((^.))
 import Data.Functor
-import Numeric.Natural (Natural)
 import Data.Tuple.Extra
 
 main :: IO ()
@@ -1481,36 +1480,36 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
   [ testGroup "Hiding strategy works"
     [ testGroup "fromList"
         [ testCase "AVec" $
-            compareHideFunctionTo
+            compareHideFunctionTo [(8,9),(10,8)]
                 "Use AVec for fromList, hiding other imports"
                 "HideFunction.hs.expected.fromList.A"
         , testCase "BVec" $
-            compareHideFunctionTo
+            compareHideFunctionTo [(8,9),(10,8)]
                 "Use BVec for fromList, hiding other imports"
                 "HideFunction.hs.expected.fromList.B"
         ]
     , testGroup "(++)"
         [testCase "EVec" $
-            compareHideFunctionTo
+            compareHideFunctionTo [(8,9),(10,8)]
                 "Use EVec for ++, hiding other imports"
                 "HideFunction.hs.expected.append.E"
         ]
     , testGroup "Vec (type)"
         [ testCase "AVec" $
             compareTwo
-                "HideType.hs"
+                "HideType.hs" [(8,15)]
                 "Use AVec for Vec, hiding other imports"
                 "HideType.hs.expected.A"
         , testCase "EVec" $
             compareTwo
-                "HideType.hs"
+                "HideType.hs" [(8,15)]
                 "Use EVec for Vec, hiding other imports"
                 "HideType.hs.expected.E"
         ]
     ]
   , testGroup "Qualify strategy"
     [ testCase "won't suggest full name for qualified module" $
-      withHideFunction $ \_ actions -> do
+      withHideFunction [(8,9),(10,8)] $ \_ actions -> do
         liftIO $
             assertBool "EVec.fromList must not be suggested" $
                 "Replace with qualified: EVec.fromList" `notElem`
@@ -1525,13 +1524,13 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
                 ]
     , testGroup "fromList"
         [ testCase "EVec" $
-            compareHideFunctionTo
+            compareHideFunctionTo [(8,9),(10,8)]
                 "Replace with qualified: E.fromList"
                 "HideFunction.hs.expected.qualified.fromList.E"
         ]
     , testGroup "(++)"
         [ testCase "Prelude" $
-            compareHideFunctionTo
+            compareHideFunctionTo [(8,9),(10,8)]
                 "Replace with qualified: Prelude.++"
                 "HideFunction.hs.expected.qualified.append.Prelude"
         ]
@@ -1539,8 +1538,8 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
   ]
   where
     hidingDir = "test/data/hiding"
-    compareTwo original cmd expected =
-        withTarget original $ \doc actions -> do
+    compareTwo original locs cmd expected =
+        withTarget original locs $ \doc actions -> do
             expected <- liftIO $
                 readFileUtf8 (hidingDir </> expected)
             action <- liftIO $ pickActionWithTitle cmd actions
@@ -1548,34 +1547,20 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             contentAfterAction <- documentContents doc
             liftIO $ T.replace "\r\n" "\n" expected @=? contentAfterAction
     compareHideFunctionTo = compareTwo "HideFunction.hs"
-    withTarget file k = runInDir hidingDir $ do
+    auxFiles = ["AVec.hs", "BVec.hs", "CVec.hs", "DVec.hs", "EVec.hs"]
+    withTarget file locs k = withTempDir $ \dir -> runInDir dir $ do
+        liftIO $ mapM_ (\fp -> copyFile (hidingDir </> fp) $ dir </> fp)
+            $ file : auxFiles
         doc <- openDoc file "haskell"
         void (skipManyTill anyMessage message
             :: Session WorkDoneProgressEndNotification)
-        void waitForDiagnostics
+        void $ expectDiagnostics [(file, [(DsError, loc, "Ambiguous occurrence") | loc <- locs])]
         contents <- documentContents doc
         let range = Range (Position 0 0) (Position (length $ T.lines contents) 0)
-        actions <- waitForAtLeatOneAction 0.5 4 doc range
+        actions <- getCodeActions doc range
         k doc actions
     withHideFunction = withTarget ("HideFunction" <.> "hs")
 
-waitForAtLeatOneAction ::
-    -- | Waiting interval
-    Double ->
-    -- | Maximum # of retry (0 for no retry at ll)
-    Natural ->
-    TextDocumentIdentifier ->
-    Range ->
-    Session [CAResult]
-waitForAtLeatOneAction wait count doc range = go count []
-    where
-        go !remain !acc = do
-            liftIO $ sleep wait
-            actions <- getCodeActions doc range
-            if not (null actions) || remain <= 0
-                then pure $ acc ++ actions
-                else go (remain - 1) (acc ++ actions)
-
 disableWarningTests :: TestTree
 disableWarningTests =
   testGroup "disable warnings" $

From 130afec61e71b94bc25c48e150aed3cbba4c024c Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 22:39:43 +0900
Subject: [PATCH 28/43] Case for Prelude.++

---
 .../hiding/HideFunction.hs.expected.append.Prelude    | 11 +++++++++++
 ghcide/test/exe/Main.hs                               |  6 +++++-
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 ghcide/test/data/hiding/HideFunction.hs.expected.append.Prelude

diff --git a/ghcide/test/data/hiding/HideFunction.hs.expected.append.Prelude b/ghcide/test/data/hiding/HideFunction.hs.expected.append.Prelude
new file mode 100644
index 0000000000..0b202451f0
--- /dev/null
+++ b/ghcide/test/data/hiding/HideFunction.hs.expected.append.Prelude
@@ -0,0 +1,11 @@
+module HideFunction where
+
+import AVec (fromList)
+import BVec (fromList,)
+import CVec hiding ((++), cons)
+import DVec hiding ((++), cons, snoc)
+import EVec as E hiding ((++))
+
+theFun = fromList
+
+theOp = (++)
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 1b025316cb..f43020bd82 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1489,10 +1489,14 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
                 "HideFunction.hs.expected.fromList.B"
         ]
     , testGroup "(++)"
-        [testCase "EVec" $
+        [ testCase "EVec" $
             compareHideFunctionTo [(8,9),(10,8)]
                 "Use EVec for ++, hiding other imports"
                 "HideFunction.hs.expected.append.E"
+        , testCase "Prelude" $
+            compareHideFunctionTo [(8,9),(10,8)]
+                "Use EVec for ++, hiding other imports"
+                "HideFunction.hs.expected.append.Prelude"
         ]
     , testGroup "Vec (type)"
         [ testCase "AVec" $

From a3486ac6b069cf8a03f11197ed35ff14a318dc2f Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 22:49:26 +0900
Subject: [PATCH 29/43] Corrects test name

---
 ghcide/test/exe/Main.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index f43020bd82..44bb9b6dd7 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1495,7 +1495,7 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
                 "HideFunction.hs.expected.append.E"
         , testCase "Prelude" $
             compareHideFunctionTo [(8,9),(10,8)]
-                "Use EVec for ++, hiding other imports"
+                "Use Prelude for ++, hiding other imports"
                 "HideFunction.hs.expected.append.Prelude"
         ]
     , testGroup "Vec (type)"

From c252aca111a34cb33849b480b659c44744e26012 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sat, 30 Jan 2021 22:50:00 +0900
Subject: [PATCH 30/43] Renames `rawIEWrapName` to `unqualIEWrapName`, and
 moved to the appropriate module

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 14 +++++++------
 .../IDE/Plugin/CodeAction/ExactPrint.hs       | 20 +++++++------------
 ghcide/src/Development/IDE/Spans/Common.hs    |  8 ++++++++
 3 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 45dc2a7d65..436ed5457e 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -61,6 +61,8 @@ import Data.Coerce
 import Data.Either (fromRight)
 import qualified GHC.LanguageExtensions as Lang
 import Control.Lens (foldMapBy)
+import FieldLabel (flLabel)
+import FastString (unpackFS)
 
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
@@ -845,13 +847,13 @@ occursUnqualified _ _ = False
 
 symbolOccursIn :: T.Text -> IE GhcPs -> Bool
 symbolOccursIn symb = \case
-   IEVar _ (L _ n) -> rawIEWrapName n == T.unpack symb
-   IEThingAbs _ (L _ n) -> rawIEWrapName n == T.unpack symb
-   IEThingAll _ (L _ n) -> rawIEWrapName n == T.unpack symb
+   IEVar _ (L _ n) -> unqualIEWrapName n == symb
+   IEThingAbs _ (L _ n) -> unqualIEWrapName n == symb
+   IEThingAll _ (L _ n) -> unqualIEWrapName n == symb
    IEThingWith _ (L _ n) _ ents flds ->
-    rawIEWrapName n == T.unpack symb
-    || any ((== symb) . showNameWithoutUniques . unLoc) ents
-    || any ((== symb) . showNameWithoutUniques . unLoc) flds
+    unqualIEWrapName n == symb
+    || any ((== symb) . unqualIEWrapName . unLoc) ents
+    || any ((== symb) . T.pack . unpackFS . flLabel . unLoc) flds
    IEModuleContents{} -> False
    IEGroup{} -> False
    IEDoc{} -> False
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index d22c01893a..81ccd5085f 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -7,7 +7,6 @@ module Development.IDE.Plugin.CodeAction.ExactPrint
   ( Rewrite (..),
     rewriteToEdit,
     transferAnn,
-    rawIEWrapName,
 
     -- * Utilities
     appendConstraint,
@@ -39,6 +38,7 @@ import Language.Haskell.LSP.Types
 import OccName
 import Outputable (ppr, showSDocUnsafe)
 import Retrie.GHC (rdrNameOcc, unpackFS)
+import Development.IDE.Spans.Common
 
 ------------------------------------------------------------------------------
 
@@ -367,7 +367,7 @@ deleteFromImport ::
     Located [LIE GhcPs] ->
     DynFlags ->
     TransformT (Either String) (LImportDecl GhcPs)
-deleteFromImport symbol (L l idecl) llies@(L lieLoc lies) _ =do
+deleteFromImport (T.pack -> symbol) (L l idecl) llies@(L lieLoc lies) _ =do
     let edited = L lieLoc deletedLies
         lidecl' = L l $ idecl
             { ideclHiding = Just (False, edited)
@@ -383,23 +383,17 @@ deleteFromImport symbol (L l idecl) llies@(L lieLoc lies) _ =do
         deletedLies =
             mapMaybe killLie lies
         killLie :: LIE GhcPs -> Maybe (LIE GhcPs)
-        killLie v@(L _ (IEVar _ (L _ (rawIEWrapName -> nam))))
+        killLie v@(L _ (IEVar _ (L _ (unqualIEWrapName -> nam))))
             | nam == symbol  = Nothing
             | otherwise = Just v
-        killLie v@(L _ (IEThingAbs _ (L _ (rawIEWrapName -> nam))))
+        killLie v@(L _ (IEThingAbs _ (L _ (unqualIEWrapName -> nam))))
             | nam == symbol = Nothing
             | otherwise = Just v
 
-        killLie (L lieL (IEThingWith xt ty@(L _ (rawIEWrapName -> nam)) wild cons flds))
+        killLie (L lieL (IEThingWith xt ty@(L _ (unqualIEWrapName -> nam)) wild cons flds))
             | nam == symbol = Nothing
             | otherwise = Just $
                 L lieL $ IEThingWith xt ty wild
-                  (filter ((/= symbol) . rawIEWrapName . unLoc) cons)
-                  (filter ((/= symbol) . unpackFS . flLabel . unLoc) flds)
+                  (filter ((/= symbol) . unqualIEWrapName . unLoc) cons)
+                  (filter ((/= symbol) . T.pack . unpackFS . flLabel . unLoc) flds)
         killLie v = Just v
-
--- This must not belong here?
-rawIEWrapName :: IEWrappedName RdrName -> String
-rawIEWrapName (IEName (L _ nam)) = occNameString $ rdrNameOcc nam
-rawIEWrapName (IEPattern (L _ nam)) = occNameString $ rdrNameOcc nam
-rawIEWrapName (IEType (L _ nam)) = occNameString $ rdrNameOcc nam
diff --git a/ghcide/src/Development/IDE/Spans/Common.hs b/ghcide/src/Development/IDE/Spans/Common.hs
index e7ad090e5e..b690f84ed7 100644
--- a/ghcide/src/Development/IDE/Spans/Common.hs
+++ b/ghcide/src/Development/IDE/Spans/Common.hs
@@ -6,6 +6,7 @@
 module Development.IDE.Spans.Common (
   showGhc
 , showNameWithoutUniques
+, unqualIEWrapName
 , safeTyThingId
 , safeTyThingType
 , SpanDoc(..)
@@ -35,6 +36,7 @@ import qualified Documentation.Haddock.Parser as H
 import qualified Documentation.Haddock.Types as H
 import Development.IDE.GHC.Orphans ()
 import Development.IDE.GHC.Util
+import RdrName (rdrNameOcc)
 
 type DocMap = NameEnv SpanDoc
 type KindMap = NameEnv TyThing
@@ -52,6 +54,12 @@ showNameWithoutUniques = T.pack . prettyprint
     prettyprint x = renderWithStyle dyn (ppr x) style
     style = mkUserStyle dyn neverQualify AllTheWay
 
+-- | Shows IEWrappedName, without any modifier, qualifier or unique identifier.
+unqualIEWrapName :: IEWrappedName RdrName -> T.Text
+unqualIEWrapName (IEName (L _ nam)) = showNameWithoutUniques $ rdrNameOcc nam
+unqualIEWrapName (IEPattern (L _ nam)) = showNameWithoutUniques $ rdrNameOcc nam
+unqualIEWrapName (IEType (L _ nam)) = showNameWithoutUniques $ rdrNameOcc nam
+
 -- From haskell-ide-engine/src/Haskell/Ide/Engine/Support/HieExtras.hs
 safeTyThingType :: TyThing -> Maybe Type
 safeTyThingType thing

From f6594fdf95be64df62561e19192dc7d080b22009 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 00:26:54 +0900
Subject: [PATCH 31/43] Rewrote qualifying strategy with `Rewrite`

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 436ed5457e..a26fb51c4f 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -889,10 +889,10 @@ disambiguateSymbol df pm Diagnostic {..} (T.unpack -> symbol) = \case
     (ToQualified qualMod) ->
         let occSym = mkVarOcc symbol
             rdr = Qual qualMod occSym
-        in [Left $ TextEdit _range
-            $ T.pack $ showSDoc df
-            $ parenSymOcc occSym
-            $ ppr rdr]
+        in [Right $ Rewrite (rangeToSrcSpan nfp _range) $ \df -> do
+            liftParseAST @(HsExpr GhcPs) df $ prettyPrint $ HsVar @GhcPs noExtField
+                $ L (UnhelpfulSpan "") rdr
+            ]
 
 -- Couldn't make out how to add New imports by ghc-exactprint;
 -- using direct TextEdit instead.

From e6946941511e5c19f4bfb02f21ceb58bb23a2e90 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 02:37:16 +0900
Subject: [PATCH 32/43] Use exactprint also for hideImplicitPreludeSymbol

---
 ghcide/src/Development/IDE/GHC/Error.hs       | 18 +++++++
 .../src/Development/IDE/Plugin/CodeAction.hs  | 29 ++++------
 .../IDE/Plugin/CodeAction/ExactPrint.hs       | 54 +++++++++++--------
 .../test/data/hiding/HidePreludeIndented.hs   |  4 ++
 .../hiding/HidePreludeIndented.hs.expected    |  5 ++
 ghcide/test/exe/Main.hs                       |  5 ++
 6 files changed, 72 insertions(+), 43 deletions(-)
 create mode 100644 ghcide/test/data/hiding/HidePreludeIndented.hs
 create mode 100644 ghcide/test/data/hiding/HidePreludeIndented.hs.expected

diff --git a/ghcide/src/Development/IDE/GHC/Error.hs b/ghcide/src/Development/IDE/GHC/Error.hs
index bce5cc733f..9e06ea9a5c 100644
--- a/ghcide/src/Development/IDE/GHC/Error.hs
+++ b/ghcide/src/Development/IDE/GHC/Error.hs
@@ -17,6 +17,9 @@ module Development.IDE.GHC.Error
   , realSrcLocToPosition
   , realSrcSpanToLocation
   , srcSpanToFilename
+  , rangeToSrcSpan
+  , rangeToRealSrcSpan
+  , positionToRealSrcLoc
   , zeroSpan
   , realSpan
   , isInsideSrcSpan
@@ -39,6 +42,7 @@ import Panic
 import           ErrUtils
 import           SrcLoc
 import qualified Outputable                 as Out
+import Data.String (fromString)
 
 
 
@@ -102,6 +106,20 @@ srcSpanToLocation src = do
   -- important that the URI's we produce have been properly normalized, otherwise they point at weird places in VS Code
   pure $ Location (fromNormalizedUri $ filePathToUri' $ toNormalizedFilePath' fs) rng
 
+rangeToSrcSpan :: NormalizedFilePath -> Range -> SrcSpan
+rangeToSrcSpan = fmap RealSrcSpan . rangeToRealSrcSpan
+
+rangeToRealSrcSpan
+    :: NormalizedFilePath -> Range -> RealSrcSpan
+rangeToRealSrcSpan nfp =
+    mkRealSrcSpan
+        <$> positionToRealSrcLoc nfp . _start
+        <*> positionToRealSrcLoc nfp . _end
+
+positionToRealSrcLoc :: NormalizedFilePath -> Position -> RealSrcLoc
+positionToRealSrcLoc nfp (Position l c)=
+    mkRealSrcLoc (fromString $ fromNormalizedFilePath nfp) (l + 1) (c + 1)
+
 isInsideSrcSpan :: Position -> SrcSpan -> Bool
 p `isInsideSrcSpan` r = case srcSpanToRange r of
   Just (Range sp ep) -> sp <= p && p <= ep
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index a26fb51c4f..1bff2409bb 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -50,7 +50,7 @@ import Safe (atMay)
 import Bag (isEmptyBag)
 import qualified Data.HashSet as Set
 import Control.Concurrent.Extra (readVar)
-import Development.IDE.GHC.Util (printRdrName)
+import Development.IDE.GHC.Util (printRdrName, prettyPrint)
 import Ide.PluginUtils (subRange)
 import Ide.Types
 import Data.Hashable (Hashable)
@@ -114,8 +114,9 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
           | x <- xs
           , ps <- maybeToList annotatedPS
           , dynflags <- maybeToList df
+          , nfp <- maybeToList mbFile
           , (title, edRewrs) <-
-                suggestImportDisambiguation dynflags (astA ps) x
+                suggestImportDisambiguation nfp dynflags (astA ps) x
           , let edit =
                     foldMapBy unionWSEdit mempty
                     (either
@@ -770,11 +771,12 @@ isPreludeImplicit = xopt Lang.ImplicitPrelude
 
 -- | Suggests disambiguation for ambiguous symbols.
 suggestImportDisambiguation ::
+    NormalizedFilePath ->
     DynFlags ->
     ParsedSource ->
     Diagnostic ->
     [(T.Text, [Either TextEdit Rewrite])]
-suggestImportDisambiguation df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic {..}
+suggestImportDisambiguation nfp df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | Just [ambiguous] <-
         matchRegexUnifySpaces
             _message
@@ -805,7 +807,7 @@ suggestImportDisambiguation df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic
             | Just targets <- mapM toModuleTarget mods =
                 sortOn fst
                 [ ( renderUniquify mode modNameText symbol
-                  , disambiguateSymbol df ps diag symbol mode
+                  , disambiguateSymbol nfp ps diag symbol mode
                   )
                 | (modTarget, restImports) <- oneAndOthers targets
                 , let modName = targetModuleName modTarget
@@ -868,13 +870,13 @@ targetModuleName (ExistingImp _) =
     error "Cannot happen!"
 
 disambiguateSymbol ::
-    DynFlags ->
+    NormalizedFilePath  ->
     ParsedSource ->
     Diagnostic ->
     T.Text ->
     HidingMode ->
     [Either TextEdit Rewrite]
-disambiguateSymbol df pm Diagnostic {..} (T.unpack -> symbol) = \case
+disambiguateSymbol nfp pm Diagnostic {..} (T.unpack -> symbol) = \case
     (HideOthers hiddens0) ->
         [ Right $ hideSymbol symbol idecl
         | ExistingImp idecls <- hiddens0
@@ -882,7 +884,7 @@ disambiguateSymbol df pm Diagnostic {..} (T.unpack -> symbol) = \case
         ]
             ++ mconcat
                 [ if null imps
-                    then [Left $ hidePreludeSymbol df symbol pm]
+                    then [Right $ hideImplicitPreludeSymbol symbol pm]
                     else Right . hideSymbol symbol <$> imps
                 | ImplicitPrelude imps <- hiddens0
                 ]
@@ -894,19 +896,6 @@ disambiguateSymbol df pm Diagnostic {..} (T.unpack -> symbol) = \case
                 $ L (UnhelpfulSpan "") rdr
             ]
 
--- Couldn't make out how to add New imports by ghc-exactprint;
--- using direct TextEdit instead.
-hidePreludeSymbol :: DynFlags -> String -> ParsedSource -> TextEdit
-hidePreludeSymbol df symbol (L _ HsModule{..}) =
-    let ran = fromJust $ srcSpanToRange $ getLoc $ last hsmodImports
-        col = _character $ _start ran
-        beg = Position (1 + _line (_end ran)) 0
-        symOcc = mkVarOcc symbol
-        symImp = T.pack $ showSDoc df $ parenSymOcc symOcc $ ppr symOcc
-    in TextEdit
-        (Range beg beg)
-      $ T.replicate col " " <> "import Prelude hiding (" <> symImp <> ")\n"
-
 findImportDeclByRange :: [LImportDecl GhcPs] -> Range -> Maybe (LImportDecl GhcPs)
 findImportDeclByRange xs range = find (\(L l _)-> srcSpanToRange l == Just range) xs
 
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index 81ccd5085f..dae612c7ae 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -11,6 +11,7 @@ module Development.IDE.Plugin.CodeAction.ExactPrint
     -- * Utilities
     appendConstraint,
     extendImport,
+    hideImplicitPreludeSymbol,
     hideSymbol,
     liftParseAST,
   )
@@ -31,14 +32,15 @@ import Development.IDE.GHC.ExactPrint
     ( Annotate, ASTElement(parseAST) )
 import Development.IDE.Types.Location
 import FieldLabel (flLabel)
-import GhcPlugins (realSrcSpanEnd, realSrcSpanStart, sigPrec)
+import GhcPlugins (sigPrec)
 import Language.Haskell.GHC.ExactPrint
 import Language.Haskell.GHC.ExactPrint.Types (DeltaPos (DP), KeywordId (G), mkAnnKey)
 import Language.Haskell.LSP.Types
 import OccName
-import Outputable (ppr, showSDocUnsafe)
-import Retrie.GHC (rdrNameOcc, unpackFS)
+import Outputable (ppr, showSDocUnsafe, showSDoc)
+import Retrie.GHC (rdrNameOcc, unpackFS, mkRealSrcSpan, realSrcSpanEnd)
 import Development.IDE.Spans.Common
+import Development.IDE.GHC.Error
 
 ------------------------------------------------------------------------------
 
@@ -63,36 +65,20 @@ rewriteToEdit ::
   Rewrite ->
   Either String WorkspaceEdit
 rewriteToEdit dflags uri anns (Rewrite dst f) = do
-  (ast, (anns, _), _) <- runTransformT anns $ f dflags
+  (ast, (anns, _), _) <- runTransformT anns $ do
+      ast <- f dflags
+      ast <$ setEntryDPT ast (DP (0,0))
   let editMap =
         HMap.fromList
           [ ( uri,
               List
                 [ TextEdit (fromJust $ srcSpanToRange dst) $
-                    stripPrecedingNewline $ T.pack $ tail $ exactPrint ast anns
+                    T.pack $ exactPrint ast anns
                 ]
             )
           ]
   pure $ WorkspaceEdit (Just editMap) Nothing
 
-stripPrecedingNewline
-    :: T.Text -> T.Text
-stripPrecedingNewline = T.dropWhile (`elem` ("\r\n" :: [Char]))
-
-srcSpanToRange :: SrcSpan -> Maybe Range
-srcSpanToRange (UnhelpfulSpan _) = Nothing
-srcSpanToRange (RealSrcSpan real) = Just $ realSrcSpanToRange real
-
-realSrcSpanToRange :: RealSrcSpan -> Range
-realSrcSpanToRange real =
-  Range
-    (realSrcLocToPosition $ realSrcSpanStart real)
-    (realSrcLocToPosition $ realSrcSpanEnd real)
-
-realSrcLocToPosition :: RealSrcLoc -> Position
-realSrcLocToPosition real =
-  Position (srcLocLine real - 1) (srcLocCol real - 1)
-
 ------------------------------------------------------------------------------
 
 -- | Fix the parentheses around a type context
@@ -397,3 +383,25 @@ deleteFromImport (T.pack -> symbol) (L l idecl) llies@(L lieLoc lies) _ =do
                   (filter ((/= symbol) . unqualIEWrapName . unLoc) cons)
                   (filter ((/= symbol) . T.pack . unpackFS . flLabel . unLoc) flds)
         killLie v = Just v
+
+hideImplicitPreludeSymbol
+    :: String -> ParsedSource -> Rewrite
+hideImplicitPreludeSymbol symbol (L _ HsModule{..}) =
+    let -- We assume there is at least one import, to collide with Prelude;
+        -- otherwise (custom) Prelude must be buggy, (or preprocessor adds some collision?)
+        existingImp = last hsmodImports
+        exisImpSpan = fromJust $ realSpan $ getLoc existingImp
+        indentation = srcSpanStartCol exisImpSpan
+        beg = realSrcSpanEnd exisImpSpan
+        ran = RealSrcSpan $ mkRealSrcSpan beg beg
+    in Rewrite ran $ \df -> do
+        -- Re-labeling is needed to reflect annotations correctly
+        let symOcc = mkVarOcc symbol
+            symImp = T.pack $ showSDoc df $ parenSymOcc symOcc $ ppr symOcc
+            impStmt = "import Prelude hiding (" <> symImp <> ")"
+
+        L _ idecl0 <- liftParseAST @(ImportDecl GhcPs) df $ T.unpack impStmt
+        let idecl = L ran idecl0
+        addSimpleAnnT idecl (DP (1,indentation - 1))
+            [(G AnnImport, DP (1, indentation - 1))]
+        pure idecl
diff --git a/ghcide/test/data/hiding/HidePreludeIndented.hs b/ghcide/test/data/hiding/HidePreludeIndented.hs
new file mode 100644
index 0000000000..122b64a390
--- /dev/null
+++ b/ghcide/test/data/hiding/HidePreludeIndented.hs
@@ -0,0 +1,4 @@
+module HidePreludeIndented where
+
+   import AVec
+   op = (++)
diff --git a/ghcide/test/data/hiding/HidePreludeIndented.hs.expected b/ghcide/test/data/hiding/HidePreludeIndented.hs.expected
new file mode 100644
index 0000000000..4218338bee
--- /dev/null
+++ b/ghcide/test/data/hiding/HidePreludeIndented.hs.expected
@@ -0,0 +1,5 @@
+module HidePreludeIndented where
+
+   import AVec
+   import Prelude hiding ((++))
+   op = (++)
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 44bb9b6dd7..6d6b9538db 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1497,6 +1497,11 @@ suggestImportDisambiguationTests = testGroup "suggest import disambiguation acti
             compareHideFunctionTo [(8,9),(10,8)]
                 "Use Prelude for ++, hiding other imports"
                 "HideFunction.hs.expected.append.Prelude"
+        , testCase "AVec, indented" $
+            compareTwo "HidePreludeIndented.hs" [(3,8)]
+            "Use AVec for ++, hiding other imports"
+            "HidePreludeIndented.hs.expected"
+
         ]
     , testGroup "Vec (type)"
         [ testCase "AVec" $

From 0550b6f00894c64a3de83031663ba388597a7d35 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 02:43:36 +0900
Subject: [PATCH 33/43] Unify exact actions and `suggestImportDisambiguation`

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 42 ++++++-------------
 1 file changed, 12 insertions(+), 30 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 1bff2409bb..a21a40a004 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -58,7 +58,6 @@ import qualified Data.DList as DL
 import Development.IDE.Spans.Common
 import OccName
 import Data.Coerce
-import Data.Either (fromRight)
 import qualified GHC.LanguageExtensions as Lang
 import Control.Lens (foldMapBy)
 import FieldLabel (flLabel)
@@ -102,33 +101,14 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
         , let edit = WorkspaceEdit (Just $ Map.singleton uri $ List tedit) Nothing
         ]
       actions' =
-          [mkCA title [x] edit
-          | x <- xs
-          , Just ps <- [annotatedPS]
-          , Just dynflags <- [df]
-          , (title, grafts) <- suggestExactAction exportsMap dynflags ps x
-          , let edit = foldMapBy unionWSEdit mempty (either error id .
-                        rewriteToEdit dynflags uri (annsA ps)) grafts
-          ] ++
           [mkCA title [x] edit
           | x <- xs
           , ps <- maybeToList annotatedPS
           , dynflags <- maybeToList df
           , nfp <- maybeToList mbFile
-          , (title, edRewrs) <-
-                suggestImportDisambiguation nfp dynflags (astA ps) x
-          , let edit =
-                    foldMapBy unionWSEdit mempty
-                    (either
-                        (\te -> WorkspaceEdit
-                                { _changes = Just $ Map.singleton uri $ List [te]
-                                , _documentChanges = Nothing }
-                        )
-                        (-- either (Left . traceShow) Right $
-                            fromRight mempty.
-                        rewriteToEdit dynflags uri (annsA ps))
-                    ) edRewrs
-
+          , (title, grafts) <- suggestExactAction exportsMap nfp dynflags ps x
+          , let edit = foldMapBy unionWSEdit mempty (either error id .
+                        rewriteToEdit dynflags uri (annsA ps)) grafts
           ]
       actions'' = caRemoveRedundantImports parsedModule text diag xs uri
                <> actions
@@ -156,15 +136,17 @@ mkCA title diags edit =
 
 suggestExactAction ::
   ExportsMap ->
+  NormalizedFilePath ->
   DynFlags ->
   Annotated ParsedSource ->
   Diagnostic ->
   [(T.Text, [Rewrite])]
-suggestExactAction exportsMap df ps x =
+suggestExactAction exportsMap nfp df ps x =
   concat
     [ suggestConstraint df (astA ps) x
     , suggestImplicitParameter (astA ps) x
     , suggestExtendImport exportsMap (astA ps) x
+    , suggestImportDisambiguation nfp df (astA ps) x
     ]
 
 suggestAction
@@ -775,7 +757,7 @@ suggestImportDisambiguation ::
     DynFlags ->
     ParsedSource ->
     Diagnostic ->
-    [(T.Text, [Either TextEdit Rewrite])]
+    [(T.Text, [Rewrite])]
 suggestImportDisambiguation nfp df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | Just [ambiguous] <-
         matchRegexUnifySpaces
@@ -875,23 +857,23 @@ disambiguateSymbol ::
     Diagnostic ->
     T.Text ->
     HidingMode ->
-    [Either TextEdit Rewrite]
+    [Rewrite]
 disambiguateSymbol nfp pm Diagnostic {..} (T.unpack -> symbol) = \case
     (HideOthers hiddens0) ->
-        [ Right $ hideSymbol symbol idecl
+        [ hideSymbol symbol idecl
         | ExistingImp idecls <- hiddens0
         , idecl <- NE.toList idecls
         ]
             ++ mconcat
                 [ if null imps
-                    then [Right $ hideImplicitPreludeSymbol symbol pm]
-                    else Right . hideSymbol symbol <$> imps
+                    then [hideImplicitPreludeSymbol symbol pm]
+                    else hideSymbol symbol <$> imps
                 | ImplicitPrelude imps <- hiddens0
                 ]
     (ToQualified qualMod) ->
         let occSym = mkVarOcc symbol
             rdr = Qual qualMod occSym
-        in [Right $ Rewrite (rangeToSrcSpan nfp _range) $ \df -> do
+        in [Rewrite (rangeToSrcSpan nfp _range) $ \df -> do
             liftParseAST @(HsExpr GhcPs) df $ prettyPrint $ HsVar @GhcPs noExtField
                 $ L (UnhelpfulSpan "") rdr
             ]

From bf99f31a17d1b93a7b0969913efbb582ef884a73 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 02:48:54 +0900
Subject: [PATCH 34/43] Moves a comment to the right place

---
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index dae612c7ae..00b5fa436c 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -395,11 +395,11 @@ hideImplicitPreludeSymbol symbol (L _ HsModule{..}) =
         beg = realSrcSpanEnd exisImpSpan
         ran = RealSrcSpan $ mkRealSrcSpan beg beg
     in Rewrite ran $ \df -> do
-        -- Re-labeling is needed to reflect annotations correctly
         let symOcc = mkVarOcc symbol
             symImp = T.pack $ showSDoc df $ parenSymOcc symOcc $ ppr symOcc
             impStmt = "import Prelude hiding (" <> symImp <> ")"
 
+        -- Re-labeling is needed to reflect annotations correctly
         L _ idecl0 <- liftParseAST @(ImportDecl GhcPs) df $ T.unpack impStmt
         let idecl = L ran idecl0
         addSimpleAnnT idecl (DP (1,indentation - 1))

From d96d6126b9df7e0f6030f0df2229810d21b23765 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 02:52:41 +0900
Subject: [PATCH 35/43] Won't panic on errornous input, let HLS keep going

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index a21a40a004..ee28614485 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -107,7 +107,7 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
           , dynflags <- maybeToList df
           , nfp <- maybeToList mbFile
           , (title, grafts) <- suggestExactAction exportsMap nfp dynflags ps x
-          , let edit = foldMapBy unionWSEdit mempty (either error id .
+          , let edit = foldMapBy unionWSEdit mempty (either mempty id .
                         rewriteToEdit dynflags uri (annsA ps)) grafts
           ]
       actions'' = caRemoveRedundantImports parsedModule text diag xs uri

From 10cc8151ab02e795678b2d53a9ee35cd9b71cd48 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 03:16:40 +0900
Subject: [PATCH 36/43] No, each errornous rewrite must not be dropped
 seprately, but discarded as a whole

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index ee28614485..ac9e3c44b4 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -45,7 +45,7 @@ import Outputable (Outputable, ppr, showSDoc, showSDocUnsafe)
 import Data.Function
 import Control.Arrow ((>>>), second)
 import Data.Functor
-import Control.Applicative ((<|>))
+import Control.Applicative ((<|>), Applicative (liftA2))
 import Safe (atMay)
 import Bag (isEmptyBag)
 import qualified Data.HashSet as Set
@@ -62,6 +62,7 @@ import qualified GHC.LanguageExtensions as Lang
 import Control.Lens (foldMapBy)
 import FieldLabel (flLabel)
 import FastString (unpackFS)
+import Data.Monoid (Ap(Ap, getAp))
 
 descriptor :: PluginId -> PluginDescriptor IdeState
 descriptor plId =
@@ -107,8 +108,9 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
           , dynflags <- maybeToList df
           , nfp <- maybeToList mbFile
           , (title, grafts) <- suggestExactAction exportsMap nfp dynflags ps x
-          , let edit = foldMapBy unionWSEdit mempty (either mempty id .
-                        rewriteToEdit dynflags uri (annsA ps)) grafts
+          , Right edit
+              <- [getAp $ foldMapBy (liftA2 unionWSEdit) mempty
+                      (Ap . rewriteToEdit dynflags uri (annsA ps)) grafts]
           ]
       actions'' = caRemoveRedundantImports parsedModule text diag xs uri
                <> actions

From 82345d194bb91a13eba6bae96cabdf16be2aa906 Mon Sep 17 00:00:00 2001
From: Hiromi Ishii <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 13:47:08 +0900
Subject: [PATCH 37/43] Update ghcide/src/Development/IDE/Spans/Common.hs

Co-authored-by: Potato Hatsue <berberman@yandex.com>
---
 ghcide/src/Development/IDE/Spans/Common.hs | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/ghcide/src/Development/IDE/Spans/Common.hs b/ghcide/src/Development/IDE/Spans/Common.hs
index b690f84ed7..479c908c2a 100644
--- a/ghcide/src/Development/IDE/Spans/Common.hs
+++ b/ghcide/src/Development/IDE/Spans/Common.hs
@@ -56,9 +56,7 @@ showNameWithoutUniques = T.pack . prettyprint
 
 -- | Shows IEWrappedName, without any modifier, qualifier or unique identifier.
 unqualIEWrapName :: IEWrappedName RdrName -> T.Text
-unqualIEWrapName (IEName (L _ nam)) = showNameWithoutUniques $ rdrNameOcc nam
-unqualIEWrapName (IEPattern (L _ nam)) = showNameWithoutUniques $ rdrNameOcc nam
-unqualIEWrapName (IEType (L _ nam)) = showNameWithoutUniques $ rdrNameOcc nam
+unqualIEWrapName = showNameWithoutUniques . rdrNameOcc . ieWrappedName
 
 -- From haskell-ide-engine/src/Haskell/Ide/Engine/Support/HieExtras.hs
 safeTyThingType :: TyThing -> Maybe Type

From 191df1b52549585545ae42c927660e73e049e991 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 14:30:52 +0900
Subject: [PATCH 38/43] ieNames

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 14 +-------------
 1 file changed, 1 insertion(+), 13 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index ac9e3c44b4..7435c6f833 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -832,19 +832,7 @@ occursUnqualified symbol ImportDecl{..}
 occursUnqualified _ _ = False
 
 symbolOccursIn :: T.Text -> IE GhcPs -> Bool
-symbolOccursIn symb = \case
-   IEVar _ (L _ n) -> unqualIEWrapName n == symb
-   IEThingAbs _ (L _ n) -> unqualIEWrapName n == symb
-   IEThingAll _ (L _ n) -> unqualIEWrapName n == symb
-   IEThingWith _ (L _ n) _ ents flds ->
-    unqualIEWrapName n == symb
-    || any ((== symb) . unqualIEWrapName . unLoc) ents
-    || any ((== symb) . T.pack . unpackFS . flLabel . unLoc) flds
-   IEModuleContents{} -> False
-   IEGroup{} -> False
-   IEDoc{} -> False
-   IEDocNamed{} -> False
-   XIE{} -> False
+symbolOccursIn symb = any ((== symb). showNameWithoutUniques) . ieNames
 
 targetModuleName :: ModuleTarget -> ModuleName
 targetModuleName ImplicitPrelude{} = mkModuleName "Prelude"

From 3b2b4e8978ec3326b669a0f5cd70c490bb1e3d3a Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 14:38:17 +0900
Subject: [PATCH 39/43] Makes Splice plugin compiles

---
 .../src/Ide/Plugin/Splice.hs                  | 20 ++-----------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/plugins/hls-splice-plugin/src/Ide/Plugin/Splice.hs b/plugins/hls-splice-plugin/src/Ide/Plugin/Splice.hs
index 44e6d3d3bc..373be9f919 100644
--- a/plugins/hls-splice-plugin/src/Ide/Plugin/Splice.hs
+++ b/plugins/hls-splice-plugin/src/Ide/Plugin/Splice.hs
@@ -47,12 +47,11 @@ import Ide.Plugin.Splice.Types
 import Ide.PluginUtils (mkLspCommand, responseError)
 import Development.IDE.GHC.ExactPrint
 import Ide.Types
-import Language.Haskell.GHC.ExactPrint (TransformT, setPrecedingLines, uniqueSrcSpanT)
+import Language.Haskell.GHC.ExactPrint (setPrecedingLines, uniqueSrcSpanT)
 import Language.Haskell.LSP.Core
 import Language.Haskell.LSP.Messages
 import Language.Haskell.LSP.Types
 import qualified Language.Haskell.LSP.Types.Lens as J
-import Retrie.ExactPrint (Annotated)
 import RnSplice
 import TcRnMonad
 import Data.Foldable (Foldable(foldl'))
@@ -392,10 +391,7 @@ codeAction _ state plId docId ran _ =
             ParsedModule {..} <-
                 MaybeT . runAction "splice.codeAction.GitHieAst" state $
                     use GetParsedModule fp
-            let spn =
-                    rangeToRealSrcSpan ran $
-                        fromString $
-                            fromNormalizedFilePath fp
+            let spn = rangeToRealSrcSpan fp ran
                 mouterSplice = something' (detectSplice spn) pm_parsed_source
             mcmds <- forM mouterSplice $
                 \(spliceSpan, spliceContext) ->
@@ -459,15 +455,3 @@ something' f =  go
             case f x of
               Stop -> Nothing
               resl -> foldl' (flip (<|>)) (fromSearchResult resl) (gmapQ go x)
-
-posToRealSrcLoc :: Position -> FastString -> RealSrcLoc
-posToRealSrcLoc pos fs = mkRealSrcLoc fs (line + 1) (col + 1)
-    where
-        line = _line pos
-        col = _character pos
-
-rangeToRealSrcSpan :: Range -> FastString -> RealSrcSpan
-rangeToRealSrcSpan ran fs =
-    mkRealSrcSpan
-        (posToRealSrcLoc (_start ran) fs)
-        (posToRealSrcLoc (_end ran) fs)

From d75b51eb32e09e68d832276627b5fea5c55426ff Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 16:04:53 +0900
Subject: [PATCH 40/43] Stop using nfp

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 26 +++++++------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 6cb7136d06..676e85db05 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -94,7 +94,7 @@ codeAction lsp state _ (TextDocumentIdentifier uri) _range CodeActionContext{_di
       df = ms_hspp_opts . pm_mod_summary <$> parsedModule
       actions =
         [ mkCA title  [x] edit
-        | x <- xs, (title, tedit) <- suggestAction exportsMap ideOptions mbFile parsedModule text df annotatedPS x
+        | x <- xs, (title, tedit) <- suggestAction exportsMap ideOptions parsedModule text df annotatedPS x
         , let edit = WorkspaceEdit (Just $ Map.singleton uri $ List tedit) Nothing
         ]
       actions' = caRemoveRedundantImports parsedModule text diag xs uri
@@ -120,26 +120,20 @@ rewrite _ _ _ = []
 suggestAction
   :: ExportsMap
   -> IdeOptions
-  -> Maybe NormalizedFilePath
   -> Maybe ParsedModule
   -> Maybe T.Text
   -> Maybe DynFlags
   -> Maybe (Annotated ParsedSource)
   -> Diagnostic
   -> [(T.Text, [TextEdit])]
-suggestAction packageExports ideOptions mbFile parsedModule text df annSource diag =
+suggestAction packageExports ideOptions parsedModule text df annSource diag =
     concat
    -- Order these suggestions by priority
     [ suggestSignature True diag
     , rewrite df annSource $ \_ ps -> suggestExtendImport packageExports ps diag
-    ]
-    ++ concat
-    [ rewrite df annSource $ \df ps ->
-        suggestImportDisambiguation nfp df ps diag
-    | nfp <- maybeToList mbFile
-    ] ++
-    concat [
-    suggestFillTypeWildcard diag
+    , rewrite df annSource $ \df ps ->
+        suggestImportDisambiguation df ps diag
+    , suggestFillTypeWildcard diag
     , suggestFixConstructorImport text diag
     , suggestModuleTypo diag
     , suggestReplaceIdentifier text diag
@@ -735,12 +729,11 @@ isPreludeImplicit = xopt Lang.ImplicitPrelude
 
 -- | Suggests disambiguation for ambiguous symbols.
 suggestImportDisambiguation ::
-    NormalizedFilePath ->
     DynFlags ->
     ParsedSource ->
     Diagnostic ->
     [(T.Text, [Rewrite])]
-suggestImportDisambiguation nfp df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic {..}
+suggestImportDisambiguation df ps@(L _ HsModule {hsmodImports}) diag@Diagnostic {..}
     | Just [ambiguous] <-
         matchRegexUnifySpaces
             _message
@@ -771,7 +764,7 @@ suggestImportDisambiguation nfp df ps@(L _ HsModule {hsmodImports}) diag@Diagnos
             | Just targets <- mapM toModuleTarget mods =
                 sortOn fst
                 [ ( renderUniquify mode modNameText symbol
-                  , disambiguateSymbol nfp ps diag symbol mode
+                  , disambiguateSymbol ps diag symbol mode
                   )
                 | (modTarget, restImports) <- oneAndOthers targets
                 , let modName = targetModuleName modTarget
@@ -822,13 +815,12 @@ targetModuleName (ExistingImp _) =
     error "Cannot happen!"
 
 disambiguateSymbol ::
-    NormalizedFilePath  ->
     ParsedSource ->
     Diagnostic ->
     T.Text ->
     HidingMode ->
     [Rewrite]
-disambiguateSymbol nfp pm Diagnostic {..} (T.unpack -> symbol) = \case
+disambiguateSymbol pm Diagnostic {..} (T.unpack -> symbol) = \case
     (HideOthers hiddens0) ->
         [ hideSymbol symbol idecl
         | ExistingImp idecls <- hiddens0
@@ -843,7 +835,7 @@ disambiguateSymbol nfp pm Diagnostic {..} (T.unpack -> symbol) = \case
     (ToQualified qualMod) ->
         let occSym = mkVarOcc symbol
             rdr = Qual qualMod occSym
-        in [Rewrite (rangeToSrcSpan nfp _range) $ \df -> do
+        in [Rewrite (rangeToSrcSpan "<dummy>" _range) $ \df -> do
             liftParseAST @(HsExpr GhcPs) df $ prettyPrint $ HsVar @GhcPs noExtField
                 $ L (UnhelpfulSpan "") rdr
             ]

From 13b9f2cc81580e6f70c6f089704af70ea510d17a Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 16:29:37 +0900
Subject: [PATCH 41/43] Since there is global `setEntryDPT dp00`, we don't add
 offset here

---
 ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index dd706c28b7..f1bcf1ed56 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -134,7 +134,7 @@ appendConstraint constraintT = go
       lContext <- uniqueSrcSpanT
       lTop <- uniqueSrcSpanT
       let context = L lContext [constraint]
-      addSimpleAnnT context (DP (0, 1)) $
+      addSimpleAnnT context (DP (0, 0)) $
         (G AnnDarrow, DP (0, 1))
         : concat
             [ [ (G AnnOpenP, dp00),

From 4aae21a71b22d88a847d66ffa6a432cfcac10f0c Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 22:18:52 +0900
Subject: [PATCH 42/43] Removes redundant (why warned here?)

---
 ghcide/src/Development/IDE/GHC/Orphans.hs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/GHC/Orphans.hs b/ghcide/src/Development/IDE/GHC/Orphans.hs
index be3c830794..e9a5e91538 100644
--- a/ghcide/src/Development/IDE/GHC/Orphans.hs
+++ b/ghcide/src/Development/IDE/GHC/Orphans.hs
@@ -22,7 +22,6 @@ import qualified StringBuffer               as SB
 import Data.Text (Text)
 import Data.String (IsString(fromString))
 import Retrie.ExactPrint (Annotated)
-import Data.List (foldl')
 
 
 -- Orphan instances for types from the GHC API.

From a45667b52b00d353db0a2f625e5500a5c2f00d26 Mon Sep 17 00:00:00 2001
From: Hiromi ISHII <konn.jinro@gmail.com>
Date: Sun, 31 Jan 2021 22:19:46 +0900
Subject: [PATCH 43/43] Made `hideImplicitPreludeSymbol` total

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs   | 10 ++++++----
 .../IDE/Plugin/CodeAction/ExactPrint.hs           | 15 +++++++--------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index 676e85db05..e966522373 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -828,16 +828,18 @@ disambiguateSymbol pm Diagnostic {..} (T.unpack -> symbol) = \case
         ]
             ++ mconcat
                 [ if null imps
-                    then [hideImplicitPreludeSymbol symbol pm]
+                    then maybeToList $ hideImplicitPreludeSymbol symbol pm
                     else hideSymbol symbol <$> imps
                 | ImplicitPrelude imps <- hiddens0
                 ]
     (ToQualified qualMod) ->
         let occSym = mkVarOcc symbol
             rdr = Qual qualMod occSym
-        in [Rewrite (rangeToSrcSpan "<dummy>" _range) $ \df -> do
-            liftParseAST @(HsExpr GhcPs) df $ prettyPrint $ HsVar @GhcPs noExtField
-                $ L (UnhelpfulSpan "") rdr
+         in [ Rewrite (rangeToSrcSpan "<dummy>" _range) $ \df -> do
+                liftParseAST @(HsExpr GhcPs) df $
+                    prettyPrint $
+                        HsVar @GhcPs noExtField $
+                            L (UnhelpfulSpan "") rdr
             ]
 
 findImportDeclByRange :: [LImportDecl GhcPs] -> Range -> Maybe (LImportDecl GhcPs)
diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
index f1bcf1ed56..49114c70d0 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs
@@ -39,6 +39,7 @@ import Outputable (ppr, showSDocUnsafe, showSDoc)
 import Retrie.GHC (rdrNameOcc, unpackFS, mkRealSrcSpan, realSrcSpanEnd)
 import Development.IDE.Spans.Common
 import Development.IDE.GHC.Error
+import Safe (lastMay)
 
 ------------------------------------------------------------------------------
 
@@ -376,16 +377,14 @@ deleteFromImport (T.pack -> symbol) (L l idecl) llies@(L lieLoc lies) _ =do
         killLie v = Just v
 
 hideImplicitPreludeSymbol
-    :: String -> ParsedSource -> Rewrite
-hideImplicitPreludeSymbol symbol (L _ HsModule{..}) =
-    let -- We assume there is at least one import, to collide with Prelude;
-        -- otherwise (custom) Prelude must be buggy, (or preprocessor adds some collision?)
-        existingImp = last hsmodImports
-        exisImpSpan = fromJust $ realSpan $ getLoc existingImp
-        indentation = srcSpanStartCol exisImpSpan
+    :: String -> ParsedSource -> Maybe Rewrite
+hideImplicitPreludeSymbol symbol (L _ HsModule{..}) = do
+    existingImp <- lastMay hsmodImports
+    exisImpSpan <- realSpan $ getLoc existingImp
+    let indentation = srcSpanStartCol exisImpSpan
         beg = realSrcSpanEnd exisImpSpan
         ran = RealSrcSpan $ mkRealSrcSpan beg beg
-    in Rewrite ran $ \df -> do
+    pure $ Rewrite ran $ \df -> do
         let symOcc = mkVarOcc symbol
             symImp = T.pack $ showSDoc df $ parenSymOcc symOcc $ ppr symOcc
             impStmt = "import Prelude hiding (" <> symImp <> ")"