Fix redundant import actions for names starting with _ (#2483)

* Fix redundant import actions for names starting with _

* Move CPP into compat layer

Author: Ailrun

ghcide/src/Development/IDE/GHC/Compat/Util.hs

@@ -68,7 +68,9 @@ module Development.IDE.GHC.Compat.Util (
     hGetStringBuffer,
     stringToStringBuffer,
     nextChar,
-    atEnd
+    atEnd,
+    -- * Char
+    is_ident
     ) where
 
 #if MIN_VERSION_ghc(9,0,0)
@@ -81,6 +83,7 @@ import           GHC.Data.FastString
 import           GHC.Data.Maybe
 import           GHC.Data.Pair
 import           GHC.Data.StringBuffer
+import           GHC.Parser.CharClass    (is_ident)
 import           GHC.Types.Unique
 import           GHC.Types.Unique.DFM
 import           GHC.Utils.Fingerprint
@@ -90,6 +93,7 @@ import           GHC.Utils.Panic         hiding (try)
 #else
 import           Bag
 import           BooleanFormula
+import           Ctype                   (is_ident)
 import           EnumSet
 import qualified Exception
 import           FastString

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

@@ -1525,7 +1525,7 @@ rangesForBindingImport _ _ = []
 wrapOperatorInParens :: String -> String
 wrapOperatorInParens x =
   case uncons x of
-    Just (h, _t) -> if isAlpha h then x else "(" <> x <> ")"
+    Just (h, _t) -> if is_ident h then x else "(" <> x <> ")"
     Nothing      -> mempty
 
 smallerRangesForBindingExport :: [LIE GhcPs] -> String -> [Range]

ghcide/test/exe/Main.hs

@@ -1276,19 +1276,20 @@ removeImportTests = testGroup "remove import actions"
             , "stuffB :: Integer"
             , "stuffB = 123"
             , "stuffC = ()"
+            , "_stuffD = '_'"
             ]
       _docA <- createDoc "ModuleA.hs" "haskell" contentA
       let contentB = T.unlines
             [ "{-# OPTIONS_GHC -Wunused-imports #-}"
             , "module ModuleB where"
-            , "import ModuleA (stuffA, stuffB, stuffC, stuffA)"
+            , "import ModuleA (stuffA, stuffB, _stuffD, stuffC, stuffA)"
             , "main = print stuffB"
             ]
       docB <- createDoc "ModuleB.hs" "haskell" contentB
       _ <- waitForDiagnostics
       [InR action@CodeAction { _title = actionTitle }, _]
           <- getCodeActions docB (Range (Position 2 0) (Position 2 5))
-      liftIO $ "Remove stuffA, stuffC from import" @=? actionTitle
+      liftIO $ "Remove _stuffD, stuffA, stuffC from import" @=? actionTitle
       executeCodeAction action
       contentAfterAction <- documentContents docB
       let expectedContentAfterAction = T.unlines