Fix completion for record dot syntax when record isn't known (#4619)

* Fix completion for record dot syntax when record isn't known

* Comment fix, fix test

* Appease pre-commit

Author: samuel-williams-da

ghcide-test/exe/CompletionTests.hs

@@ -33,7 +33,6 @@ import           Test.Hls.Util
 import           Test.Tasty
 import           Test.Tasty.HUnit
 
-
 tests :: TestTree
 tests
   = testGroup "completion"
@@ -61,6 +60,7 @@ completionTest :: HasCallStack => String -> [T.Text] -> Position -> [(T.Text, Co
 completionTest name src pos expected = testSessionSingleFile name "A.hs" (T.unlines src) $ do
     docId <- openDoc "A.hs" "haskell"
     _ <- waitForDiagnostics
+
     compls <- getAndResolveCompletions docId pos
     let compls' = [ (_label, _kind, _insertText, _additionalTextEdits) | CompletionItem{..} <- compls]
     let emptyToMaybe x = if T.null x then Nothing else Just x
@@ -211,7 +211,38 @@ localCompletionTests = [
 
         compls <- getCompletions doc (Position 0 15)
         liftIO $ filter ("AAA" `T.isPrefixOf`) (mapMaybe _insertText compls) @?= ["AAAAA"]
-        pure ()
+        pure (),
+    completionTest
+        "polymorphic record dot completion"
+        [ "{-# LANGUAGE OverloadedRecordDot #-}"
+        , "module A () where"
+        , "data Record = Record"
+        , "  { field1 :: Int"
+        , "  , field2 :: Int"
+        , "  }"
+        , -- Without the following, this file doesn't trigger any diagnostics, so completionTest waits forever
+          "triggerDiag :: UnknownType"
+        , "foo record = record.f"
+        ]
+        (Position 7 21)
+        [("field1", CompletionItemKind_Function, "field1", True, False, Nothing)
+        ,("field2", CompletionItemKind_Function, "field2", True, False, Nothing)
+        ],
+    completionTest
+        "qualified polymorphic record dot completion"
+        [ "{-# LANGUAGE OverloadedRecordDot #-}"
+        , "module A () where"
+        , "data Record = Record"
+        , "  { field1 :: Int"
+        , "  , field2 :: Int"
+        , "  }"
+        , "someValue = undefined"
+        , "foo = A.someValue.f"
+        ]
+        (Position 7 19)
+        [("field1", CompletionItemKind_Function, "field1", True, False, Nothing)
+        ,("field2", CompletionItemKind_Function, "field2", True, False, Nothing)
+        ]
     ]
 
 nonLocalCompletionTests :: [TestTree]

ghcide/src/Development/IDE/Plugin/Completions/Logic.hs

@@ -878,7 +878,9 @@ getCompletionPrefixFromRope pos@(Position l c) ropetext =
           [] -> Nothing
           (x:xs) -> do
             let modParts = reverse $ filter (not .T.null) xs
-                modName = T.intercalate "." modParts
+                -- Must check the prefix is a valid module name, else record dot accesses treat
+                -- the record name as a qualName for search and generated imports
+                modName = if all (isUpper . T.head) modParts then T.intercalate "." modParts else ""
             return $ PosPrefixInfo { fullLine = curLine, prefixScope = modName, prefixText = x, cursorPos = pos }
 
 completionPrefixPos :: PosPrefixInfo -> Position