fix: handle comma in extend import list with ghc 9.2 (#2697)

* fix: handle comma in extend import list with ghc 9.2

The comma annotation was missing.

Close #2662.

* Update ghcide/src/Development/IDE/Plugin/CodeAction/ExactPrint.hs

Co-authored-by: Pepe Iborra <pepeiborra@gmail.com>

* refactor: extract addCommaInImportList

Co-authored-by: Pepe Iborra <pepeiborra@gmail.com>
Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

Author: 3 people

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

@@ -49,7 +49,7 @@ import           GHC (AddEpAnn (..), AnnContext (..), AnnParen (..),
                       DeltaPos (SameLine), EpAnn (..), EpaLocation (EpaDelta),
                       IsUnicodeSyntax (NormalSyntax),
                       NameAdornment (NameParens), NameAnn (..), addAnns, ann, emptyComments,
-                      reAnnL, AnnList (..))
+                      reAnnL, AnnList (..), TrailingAnn (AddCommaAnn), addTrailingAnnToA)
 #endif
 import           Language.LSP.Types
 import Development.IDE.GHC.Util
@@ -374,11 +374,7 @@ extendImportTopLevel thing (L l it@ImportDecl{..})
           transferAnn (L l' lies) (L l' [x]) id
         return $ L l it{ideclHiding = Just (hide, L l' $ lies ++ [x])}
 #else
-
-        x <- pure $ setEntryDP x (SameLine $ if hasSibling then 1 else 0)
-
-        let fixLast = if hasSibling then first addComma else id
-            lies' = over _last fixLast lies ++ [x]
+        lies' <- addCommaInImportList lies x
         return $ L l it{ideclHiding = Just (hide, L l' lies')}
 #endif
 extendImportTopLevel _ _ = lift $ Left "Unable to extend the import list"
@@ -490,13 +486,39 @@ extendImportViaParent df parent child (L l it@ImportDecl{..})
       -- we need change the ann key from `[]` to `:` to keep parens and other anns.
       unless hasSibling $
         transferAnn (L l' $ reverse pre) (L l' [x]) id
+
+      let lies' = reverse pre ++ [x]
 #else
-          x :: LIE GhcPs = reLocA $ L l'' $ IEThingWith listAnn parentLIE NoIEWildcard [childLIE]
           listAnn = epAnn srcParent [AddEpAnn AnnOpenP (epl 1), AddEpAnn AnnCloseP (epl 0)]
+          x :: LIE GhcPs = reLocA $ L l'' $ IEThingWith listAnn parentLIE NoIEWildcard [childLIE]
+
+      let hasSibling = not (null pre)
+      lies' <- addCommaInImportList (reverse pre) x
 #endif
-      return $ L l it{ideclHiding = Just (hide, L l' $ reverse pre ++ [x])}
+      return $ L l it{ideclHiding = Just (hide, L l' lies')}
 extendImportViaParent _ _ _ _ = lift $ Left "Unable to extend the import list via parent"
 
+#if MIN_VERSION_ghc(9,2,0)
+-- Add an item in an import list, taking care of adding comma if needed.
+addCommaInImportList :: Monad m =>
+  -- | Initial list
+  [LocatedAn AnnListItem a]
+  -- | Additionnal item
+  -> LocatedAn AnnListItem a
+  -> m [LocatedAn AnnListItem a]
+addCommaInImportList lies x = do
+  let hasSibling = not (null lies)
+  -- Add the space before the comma
+  x <- pure $ setEntryDP x (SameLine $ if hasSibling then 1 else 0)
+
+  -- Add the comma (if needed)
+  let
+    fixLast = if hasSibling then first addComma else id
+    lies' = over _last fixLast lies ++ [x]
+
+  pure lies'
+#endif
+
 unIEWrappedName :: IEWrappedName (IdP GhcPs) -> String
 unIEWrappedName (occName -> occ) = showSDocUnsafe $ parenSymOcc occ (ppr occ)
 

ghcide/test/exe/Main.hs

@@ -1520,7 +1520,7 @@ extendImportTests = testGroup "extend import actions"
                     , "import ModuleA as A (stuffB, (.*))"
                     , "main = print (stuffB .* stuffB)"
                     ])
-        , knownBrokenForGhcVersions [GHC92] "missing comma. #2662" $ testSession "extend single line import with infix constructor" $ template
+        , testSession "extend single line import with infix constructor" $ template
             []
             ("ModuleB.hs", T.unlines
                     [ "module ModuleB where"
@@ -1534,7 +1534,7 @@ extendImportTests = testGroup "extend import actions"
                     , "import Data.List.NonEmpty (fromList, NonEmpty ((:|)))"
                     , "main = case (fromList []) of _ :| _ -> pure ()"
                     ])
-        , knownBrokenForGhcVersions [GHC92] "missing comma. #2662" $ testSession "extend single line import with prefix constructor" $ template
+        , testSession "extend single line import with prefix constructor" $ template
             []
             ("ModuleB.hs", T.unlines
                     [ "module ModuleB where"