Mark unused-binding diagnostic test broken on GHC 9.6

TcRnUnusedName gained structured provenance only in GHC 9.8, so 9.6
cannot identify unused top-level binds to attach the action to.

Author: crtschin

plugins/hls-export-plugin/src/Ide/Plugin/Export.hs

@@ -13,7 +13,8 @@ import           Development.IDE.Core.PluginUtils (runActionE, useE)
 import           Development.IDE.Core.Shake       (getDiagnostics)
 import           Development.IDE.GHC.Compat
 -- TcRnUnusedName (and its provenance) only became a structured diagnostic in
--- GHC 9.8. On 9.6 we cannot single out unused top-level binds this way.
+-- GHC 9.8 (GHC #20115, MR !10350). On 9.6 we cannot single out unused top-level
+-- binds this way.
 #if MIN_VERSION_ghc(9,8,0)
 import           Development.IDE.GHC.Compat.Error (_TcRnMessage,
                                                    msgEnvelopeErrorL)

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

@@ -265,7 +265,9 @@ main = defaultTestRunner $ testGroup "Export"
         ]
 
     , testGroup "Export fixes the unused-binding warning"
-        [ testCase "Export action attaches the -Wunused-top-binds diagnostic" $ runExport $ \_dir -> do
+        [ knownBrokenForGhcVersions [GHC96]
+            "TcRnUnusedName provenance is unstructured before GHC 9.8 (GHC #20115)" $
+          testCase "Export action attaches the -Wunused-top-binds diagnostic" $ runExport $ \_dir -> do
             doc <- openDoc "ExportUnusedFix.hs" "haskell"
             waitForKickDone
             actions <- rights . map toEither <$> getCodeActions doc (rangeAt 6 0)  -- on `unused`