Add supported cabal-versions to the error message

Author: fendor

plugins/hls-cabal-plugin/src/Ide/Plugin/Cabal.hs

@@ -67,6 +67,9 @@ import           Text.Regex.TDFA
 import qualified Data.Text                                     ()
 import           Distribution.Parsec.Error
 import qualified Ide.Plugin.Cabal.CabalAdd                     as CabalAdd
+import qualified Data.List as List
+import qualified Distribution.CabalSpecVersion as Cabal
+import qualified Ide.Plugin.Cabal.Completion.Data as Data
 
 data Log
   = LogModificationTime NormalizedFilePath FileVersion
@@ -252,13 +255,24 @@ cabalRules recorder plId = do
                 -- We don't support the cabal version, this should not be an error, as the
                 -- user did not do anything wrong. Instead we cast it to a warning
                 regex = "Unsupported cabal-version [0-9]+.[0-9]*"
-                unsupportedCabalHelpText = "\nThe used cabal version is not fully supported by hls. This means that some functionallity might not work as expected.\nIf you face any issues try to downgrade to a supported cabal version."
+                unsupportedCabalHelpText = unlines
+                  [ "The used cabal version is not fully supported by HLS. This means that some functionality might not work as expected."
+                  , "If you face any issues try to downgrade to a supported cabal version."
+                  , ""
+                  , "Supported versions are: " <>
+                      List.intercalate ", "
+                        (fmap Cabal.showCabalSpecVersion Data.supportedCabalVersions)
+                  ]
                 errorDiags =
                   NE.toList $
                     NE.map
                       ( \pe@(PError pos text) ->
                           if text =~ regex
-                            then Diagnostics.warningDiagnostic file (Syntax.PWarning Syntax.PWTOther pos (text <> unsupportedCabalHelpText))
+                            then Diagnostics.warningDiagnostic file (Syntax.PWarning Syntax.PWTOther pos $
+                                  unlines
+                                    [ text
+                                    , unsupportedCabalHelpText
+                                    ])
                             else Diagnostics.errorDiagnostic file pe
                       )
                       pErrorNE

plugins/hls-cabal-plugin/src/Ide/Plugin/Cabal/Completion/Data.hs

@@ -23,14 +23,17 @@ import           Ide.Plugin.Cabal.LicenseSuggest                (licenseNames)
 -- Completion Data
 -- ----------------------------------------------------------------
 
+supportedCabalVersions :: [CabalSpecVersion]
+supportedCabalVersions = [CabalSpecV2_2 .. maxBound]
+
 -- | Keyword for cabal version; required to be the top line in a cabal file
 cabalVersionKeyword :: Map KeyWordName Completer
 cabalVersionKeyword =
   Map.singleton "cabal-version:" $
     constantCompleter $
       -- We only suggest cabal versions newer than 2.2
       -- since we don't recommend using older ones.
-      map (T.pack . showCabalSpecVersion) [CabalSpecV2_2 .. maxBound]
+      map (T.pack . showCabalSpecVersion) supportedCabalVersions
 
 -- | Top level keywords of a cabal file.
 --