From a3ed20f62f2cc1a3bd2843c856ce3d4fd98e6303 Mon Sep 17 00:00:00 2001
From: Potato Hatsue <1793913507@qq.com>
Date: Fri, 26 Feb 2021 16:03:07 +0800
Subject: [PATCH 1/2] Extract the qualified name from already imported module

---
 .../src/Development/IDE/Plugin/CodeAction.hs  | 38 ++++++++++++++++++-
 ghcide/test/exe/Main.hs                       | 13 +++++++
 2 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index bfe3221fd3..d7d948d78d 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -1195,6 +1195,11 @@ suggestNewImport packageExportsMap ParsedModule {pm_parsed_source = L _ HsModule
   | msg <- unifySpaces _message
   , Just thingMissing <- extractNotInScopeName msg
   , qual <- extractQualifiedModuleName msg
+  , qual' <-
+      extractDoesNotExportModuleName msg
+        >>= (findImportDeclByModuleName hsmodImports . T.unpack)
+        >>= ideclAs . unLoc
+        <&> T.pack . moduleNameString . unLoc
   , Just insertLine <- case hsmodImports of
         [] -> case srcSpanStart $ getLoc (head hsmodDecls) of
           RealSrcLoc s -> Just $ srcLocLine s - 1
@@ -1206,7 +1211,7 @@ suggestNewImport packageExportsMap ParsedModule {pm_parsed_source = L _ HsModule
   , extendImportSuggestions <- matchRegexUnifySpaces msg
     "Perhaps you want to add ‘[^’]*’ to the import list in the import of ‘([^’]*)’"
   = [(imp, [TextEdit (Range insertPos insertPos) (imp <> "\n")])
-    | imp <- sort $ constructNewImportSuggestions packageExportsMap (qual, thingMissing) extendImportSuggestions
+    | imp <- sort $ constructNewImportSuggestions packageExportsMap (qual <|> qual', thingMissing) extendImportSuggestions
     ]
 suggestNewImport _ _ _ = []
 
@@ -1272,6 +1277,37 @@ extractQualifiedModuleName x
   | otherwise
   = Nothing
 
+-- | If a module has been imported qualified, and we want to ues the same qualifier for other modules
+-- which haven't been imported, 'extractQualifiedModuleName' won't work. Thus we need extract the qualifier
+-- from the imported one.
+--
+-- For example, we write f = T.putStrLn, where putStrLn comes from Data.Text.IO, with the following import(s):
+-- 1.
+-- import qualified Data.Text as T
+-- 
+-- Module ‘Data.Text’ does not export ‘putStrLn’.
+--
+-- 2.
+-- import qualified Data.Text as T
+-- import qualified Data.Functor as T
+--
+-- Neither ‘Data.Functor’ nor ‘Data.Text’ exports ‘putStrLn’.
+--
+-- 3.
+-- import qualified Data.Text as T
+-- import qualified Data.Functor as T
+-- import qualified Data.Function as T
+--
+-- Neither ‘Data.Function’,
+--         ‘Data.Functor’ nor ‘Data.Text’ exports ‘putStrLn’.
+extractDoesNotExportModuleName :: T.Text -> Maybe T.Text
+extractDoesNotExportModuleName x
+  | Just [m] <- 
+    matchRegexUnifySpaces x "Module ‘([^’]*)’ does not export" 
+      <|> matchRegexUnifySpaces x "nor ‘([^’]*)’ exports"
+  = Just m
+  | otherwise
+  = Nothing
 -------------------------------------------------------------------------------------------------
 
 
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index c34e97df50..308bf534f6 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -1559,6 +1559,19 @@ suggestImportTests = testGroup "suggest import actions"
     , test True []          "f = (&) [] id"               []                "import Data.Function ((&))"
     , test True []          "f = (.|.)"                   []                "import Data.Bits (Bits((.|.)))"
     , test True []          "f = (.|.)"                   []                "import Data.Bits ((.|.))"
+    , test True 
+      ["qualified Data.Text as T"
+      ]                     "f = T.putStrLn"              []                "import qualified Data.Text.IO as T"
+    , test True 
+      [ "qualified Data.Text as T"
+      , "qualified Data.Function as T"
+      ]                     "f = T.putStrLn"              []                "import qualified Data.Text.IO as T"
+    , test True 
+      [ "qualified Data.Text as T"
+      , "qualified Data.Function as T"
+      , "qualified Data.Functor as T"
+      , "qualified Data.Data as T"
+      ]                     "f = T.putStrLn"              []                "import qualified Data.Text.IO as T"
     ]
   ]
   where

From ffba5bb024888a9d3e5c4665ad5650187f8ba50a Mon Sep 17 00:00:00 2001
From: Potato Hatsue <1793913507@qq.com>
Date: Fri, 26 Feb 2021 16:06:42 +0800
Subject: [PATCH 2/2] Minor format

---
 ghcide/src/Development/IDE/Plugin/CodeAction.hs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/ghcide/src/Development/IDE/Plugin/CodeAction.hs b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
index d7d948d78d..ac7bcf5df8 100644
--- a/ghcide/src/Development/IDE/Plugin/CodeAction.hs
+++ b/ghcide/src/Development/IDE/Plugin/CodeAction.hs
@@ -1284,7 +1284,7 @@ extractQualifiedModuleName x
 -- For example, we write f = T.putStrLn, where putStrLn comes from Data.Text.IO, with the following import(s):
 -- 1.
 -- import qualified Data.Text as T
--- 
+--
 -- Module ‘Data.Text’ does not export ‘putStrLn’.
 --
 -- 2.
@@ -1302,8 +1302,8 @@ extractQualifiedModuleName x
 --         ‘Data.Functor’ nor ‘Data.Text’ exports ‘putStrLn’.
 extractDoesNotExportModuleName :: T.Text -> Maybe T.Text
 extractDoesNotExportModuleName x
-  | Just [m] <- 
-    matchRegexUnifySpaces x "Module ‘([^’]*)’ does not export" 
+  | Just [m] <-
+    matchRegexUnifySpaces x "Module ‘([^’]*)’ does not export"
       <|> matchRegexUnifySpaces x "nor ‘([^’]*)’ exports"
   = Just m
   | otherwise