Attempt to fix #4731

Author: Aster89

plugins/hls-class-plugin/src/Ide/Plugin/Class/ExactPrint.hs

@@ -24,9 +24,7 @@ makeEditText :: Monad m => ParsedModule -> DynFlags -> AddMinimalMethodsParams -
 makeEditText pm df AddMinimalMethodsParams{..} = do
     mDecls <- MaybeT . pure $ traverse (makeMethodDecl df) methodGroup
     let ps =
-#if !MIN_VERSION_ghc(9,9,0)
             makeDeltaAst $
-#endif
                 pm_parsed_source pm
 
         old = T.pack $ exactPrint ps

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

@@ -44,6 +44,8 @@ codeActionTests = testGroup
       , "Add placeholders for all missing methods"
       , "Add placeholders for all missing methods with signature(s)"
       ]
+  , goldenWithClass "Creates a placeholder for '<>'" "T8" "diamond" $
+      getActionByTitle "Add placeholders for '<>'"
   , goldenWithClass "Creates a placeholder for '=='" "T1" "eq" $
       getActionByTitle "Add placeholders for '=='"
   , goldenWithClass "Creates a placeholder for '/='" "T1" "ne" $

plugins/hls-class-plugin/test/testdata/T8.diamond.expected.hs

@@ -0,0 +1,6 @@
+data Set a = Set
+
+instance Semigroup (Set a) where
+  (<>) = _
+
+instance Monoid (Set a) where

plugins/hls-class-plugin/test/testdata/T8.hs

@@ -0,0 +1,5 @@
+data Set a = Set
+
+instance Semigroup (Set a) where
+
+instance Monoid (Set a) where