case sensitive language pragmas fix

plugins/hls-pragmas-plugin/src/Ide/Plugin/Pragmas.hs

@@ -160,7 +160,7 @@ completion _ide _ complParams = do
             result <$> VFS.getCompletionPrefix position cnts
             where
                 result (Just pfix)
-                    | "{-# LANGUAGE" `T.isPrefixOf` VFS.fullLine pfix
+                    | "{-# language" `T.isPrefixOf` T.toLower (VFS.fullLine pfix)
                     = J.List $ map buildCompletion
                         (Fuzzy.simpleFilter (VFS.prefixText pfix) allPragmas)
                     | otherwise

plugins/hls-pragmas-plugin/test/Main.hs

@@ -256,6 +256,18 @@ completionTests =
         item ^. L.label @?= "OverloadedStrings"
         item ^. L.kind @?= Just CiKeyword
 
+
+    , testCase "completes language extensions case insensitive" $ runSessionWithServer pragmasPlugin testDataDir $ do
+      doc <- openDoc "Completion.hs" "haskell"
+      _ <- waitForDiagnostics
+      let te = TextEdit (Range (Position 0 4) (Position 0 34)) "lAnGuaGe Overloaded"
+      _ <- applyEdit doc te
+      compls <- getCompletions doc (Position 0 24)
+      let item = head $ filter ((== "OverloadedStrings") . (^. L.label)) compls
+      liftIO $ do
+        item ^. L.label @?= "OverloadedStrings"
+        item ^. L.kind @?= Just CiKeyword
+
   , testCase "completes the Strict language extension" $ runSessionWithServer pragmasPlugin testDataDir $ do
       doc <- openDoc "Completion.hs" "haskell"
       _ <- waitForDiagnostics