Fix exporting operator pattern synonym (#4420)

* Add tests for export unused top binding code action

For symbolic pattern synonyms, type families and type classes

* Parenthesize symbolic pattern synonyms in add export code action

* Refactor printExport

* Remove superfluous tests

* Revert implementation to correct one

Author: pbrinkmeier

plugins/hls-refactor-plugin/src/Development/IDE/Plugin/CodeAction.hs

@@ -769,7 +769,7 @@ suggestExportUnusedTopBinding srcOpt ParsedModule{pm_parsed_source = L _ HsModul
 
     printExport :: ExportsAs -> T.Text -> T.Text
     printExport ExportName x    = parenthesizeIfNeeds False x
-    printExport ExportPattern x = "pattern " <> x
+    printExport ExportPattern x = "pattern " <> parenthesizeIfNeeds False x
     printExport ExportFamily x  = parenthesizeIfNeeds True x
     printExport ExportAll x     = parenthesizeIfNeeds True x <> "(..)"
 

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

@@ -3413,6 +3413,19 @@ exportUnusedTests = testGroup "export unused actions"
       , "module A (pattern Foo) where"
       , "pattern Foo a <- (a, _)"
       ]
+    , testSession "unused pattern synonym operator" $ template
+      [ "{-# OPTIONS_GHC -Wunused-top-binds #-}"
+      , "{-# LANGUAGE PatternSynonyms #-}"
+      , "module A () where"
+      , "pattern x :+ y = (x, y)"
+      ]
+      (R 3 0 3 12)
+      "Export ‘:+’"
+      [ "{-# OPTIONS_GHC -Wunused-top-binds #-}"
+      , "{-# LANGUAGE PatternSynonyms #-}"
+      , "module A (pattern (:+)) where"
+      , "pattern x :+ y = (x, y)"
+      ]
     , testSession "unused data type" $ template
       [ "{-# OPTIONS_GHC -Wunused-top-binds #-}"
       , "module A () where"