enable gadt for ghc-9.12

Author: GuillaumedeVolpiano

docs/support/ghc-version-support.md

@@ -17,7 +17,7 @@ Support status (see the support policy below for more details):
 
 | GHC version  | Last supporting HLS version                                                          | Support status |
 | ------------ | ------------------------------------------------------------------------------------ | -------------- |
-| 9.12.2       | [latest](https://github.com/haskell/haskell-language-server/releases/latest)         | basic support  |
+| 9.12.2       | [latest](https://github.com/haskell/haskell-language-server/releases/latest)         | full support   |
 | 9.10.1       | [latest](https://github.com/haskell/haskell-language-server/releases/latest)         | full support   |
 | 9.8.4        | [latest](https://github.com/haskell/haskell-language-server/releases/latest)         | full support   |
 | 9.8.2        | [2.9.0.1](https://github.com/haskell/haskell-language-server/releases/tag/2.9.0.1)   | deprecated     |

docs/support/plugin-support.md

@@ -54,7 +54,7 @@ For example, a plugin to provide a formatter which has itself been abandoned has
 | `hls-explicit-fixity-plugin`         | 2    |                          |
 | `hls-explicit-record-fields-plugin`  | 2    |                          |
 | `hls-fourmolu-plugin`                | 2    |                          |
-| `hls-gadt-plugin`                    | 2    | 9.12.2                   |
+| `hls-gadt-plugin`                    | 2    |                          |
 | `hls-hlint-plugin`                   | 2    | 9.10.1                   |
 | `hls-module-name-plugin`             | 2    |                          |
 | `hls-notes-plugin`                   | 2    |                          |

plugins/hls-gadt-plugin/src/Ide/Plugin/GHC.hs

@@ -18,6 +18,9 @@ import           Development.IDE.GHC.Compat.ExactPrint
 import           GHC.Parser.Annotation                   (DeltaPos (..),
                                                           EpAnn (..),
                                                           EpAnnComments (EpaComments))
+#if MIN_VERSION_ghc(9,11,0)
+import           GHC.Parser.Annotation                   (EpToken(..))
+#endif
 import           Ide.PluginUtils                         (subRange)
 import           Language.Haskell.GHC.ExactPrint.Parsers (parseDecl)
 
@@ -217,7 +220,11 @@ prettyGADTDecl df decl =
         adjustDataDecl DataDecl{..} = DataDecl
             { tcdDExt = adjustWhere tcdDExt
             , tcdDataDefn = tcdDataDefn
-                { dd_cons =
+                { 
+#if MIN_VERSION_ghc(9,11,0)
+                dd_ext = adjustDefnWhere (dd_ext tcdDataDefn),
+#endif
+                dd_cons =
                       fmap adjustCon (dd_cons tcdDataDefn)
                 }
             , ..
@@ -228,7 +235,7 @@ prettyGADTDecl df decl =
         adjustCon :: LConDecl GP -> LConDecl GP
 #if MIN_VERSION_ghc(9,11,0)
         adjustCon (L _ r) =
-            let delta = EpaDelta (UnhelpfulSpan UnhelpfulNoLocationInfo) (DifferentLine 1 3) []
+            let delta = EpaDelta (UnhelpfulSpan UnhelpfulNoLocationInfo) (DifferentLine 1 2) []
             in L (EpAnn delta (AnnListItem []) (EpaComments [])) r
 #elif MIN_VERSION_ghc(9,9,0)
         adjustCon (L _ r) =
@@ -255,11 +262,24 @@ prettyGADTDecl df decl =
                 else AddEpAnn ann l
             )
 #endif
+
+#if MIN_VERSION_ghc(9,11,0)
+        adjustDefnWhere annDataDefn
+          | andd_where annDataDefn == NoEpTok = annDataDefn
+          | otherwise = annDataDefn {andd_where = andd_where'}
+          where
+            (EpTok (EpaSpan aw)) = andd_where annDataDefn
+            andd_where' = EpTok (EpaDelta aw (SameLine 1) []) 
+#endif
         -- Remove the first extra line if exist
         removeExtraEmptyLine s = case stripInfix "\n\n" s of
             Just (x, xs) -> x <> "\n" <> xs
             Nothing      -> s
 
+#if MIN_VERSION_ghc(9,11,0)
+
+#endif
+
 wrap :: forall a. WrapXRec GP a => a -> XRec GP a
 wrap = wrapXRec @GP
 wrapCtxt = id