Improve action for fixing import typo

Author: jhrcek

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

@@ -700,17 +700,33 @@ suggestFillTypeWildcard Diagnostic{_range=_range,..}
         =  [("Use type signature: ‘" <> typeSignature <> "’", TextEdit _range typeSignature)]
     | otherwise = []
 
+{- Handles two variants with different formatting
+
+1. Could not find module ‘Data.Cha’
+   Perhaps you meant Data.Char (from base-4.12.0.0)
+
+2. Could not find module ‘Data.I’
+   Perhaps you meant
+      Data.Ix (from base-4.14.3.0)
+      Data.Eq (from base-4.14.3.0)
+      Data.Int (from base-4.14.3.0)
+-}
 suggestModuleTypo :: Diagnostic -> [(T.Text, TextEdit)]
 suggestModuleTypo Diagnostic{_range=_range,..}
--- src/Development/IDE/Core/Compile.hs:58:1: error:
---     Could not find module ‘Data.Cha’
---     Perhaps you meant Data.Char (from base-4.12.0.0)
     | "Could not find module" `T.isInfixOf` _message
-    , "Perhaps you meant"     `T.isInfixOf` _message = let
-      findSuggestedModules = map (head . T.words) . drop 2 . T.lines
-      proposeModule mod = ("replace with " <> mod, TextEdit _range mod)
-      in map proposeModule $ nubOrd $ findSuggestedModules _message
+    , "Perhaps you meant"     `T.isInfixOf` _message =
+      case T.splitOn "Perhaps you meant" _message of
+          [_, stuff] ->
+              [ ("replace with " <> modul, TextEdit _range modul)
+              | modul <- mapMaybe extractModule $ T.lines stuff
+              ]
+          _ -> []
     | otherwise = []
+  where
+    extractModule line = case T.words line of
+        [modul,"(from",_] -> Just modul
+        _                 -> Nothing
+    
 
 suggestFillHole :: Diagnostic -> [(T.Text, TextEdit)]
 suggestFillHole Diagnostic{_range=_range,..}

ghcide/test/exe/Main.hs

@@ -778,6 +778,7 @@ codeActionTests = testGroup "code actions"
   , suggestHideShadowTests
   , suggestImportDisambiguationTests
   , fixConstructorImportTests
+  , fixModuleImportTypoTests
   , importRenameActionTests
   , fillTypedHoleTests
   , addSigActionTests
@@ -1804,6 +1805,31 @@ extendImportTests = testGroup "extend import actions"
             contentAfterAction <- documentContents docB
             liftIO $ expectedContentB @=? contentAfterAction
 
+fixModuleImportTypoTests :: TestTree
+fixModuleImportTypoTests = testGroup "fix module import typo"
+    [ testSession "works when single module suggested" $ do
+        doc <- createDoc "A.hs" "haskell" "import Data.Cha"
+        _ <- waitForDiagnostics
+        InR action@CodeAction { _title = actionTitle } : _  <- getCodeActions doc (R 0 0 0 10)
+        liftIO $ actionTitle @?= "replace with Data.Char"
+        executeCodeAction action
+        contentAfterAction <- documentContents doc
+        liftIO $ contentAfterAction @?= "import Data.Char"
+    , testSession "works when multiple modules suggested" $ do
+        doc <- createDoc "A.hs" "haskell" "import Data.I"
+        _ <- waitForDiagnostics
+        actions <- sortOn (\(InR CodeAction{_title=x}) -> x) <$> getCodeActions doc (R 0 0 0 10)
+        let actionTitles = [ title | InR CodeAction{_title=title} <- actions ]
+        liftIO $ actionTitles @?= [ "replace with Data.Eq"
+                                  , "replace with Data.Int"
+                                  , "replace with Data.Ix"
+                                  ]
+        let InR replaceWithDataEq : _ = actions
+        executeCodeAction replaceWithDataEq
+        contentAfterAction <- documentContents doc
+        liftIO $ contentAfterAction @?= "import Data.Eq"
+    ]
+
 extendImportTestsRegEx :: TestTree
 extendImportTestsRegEx = testGroup "regex parsing"
     [