Fix -Wall and -Wunused-packages in change-type-signature plugin (haskell#3970)

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Co-authored-by: Michael Peyton Jones <[email protected]>

Author: 3 people

plugins/hls-change-type-signature-plugin/hls-change-type-signature-plugin.cabal

@@ -22,7 +22,11 @@ source-repository head
     type:     git
     location: https://github.com/haskell/haskell-language-server.git
 
+common warnings
+  ghc-options: -Wall -Wunused-packages
+
 library
+  import: warnings
   exposed-modules:  Ide.Plugin.ChangeTypeSignature
   hs-source-dirs:   src
   build-depends:
@@ -34,9 +38,7 @@ library
     , syb
     , text
     , transformers
-    , unordered-containers
     , containers
-  ghc-options: -Wall
   default-language: Haskell2010
   default-extensions:
     ConstraintKinds
@@ -50,18 +52,17 @@ library
 
 
 test-suite tests
+  import:           warnings
   type:             exitcode-stdio-1.0
   default-language: Haskell2010
   hs-source-dirs:   test
   main-is:          Main.hs
-  ghc-options:      -threaded -rtsopts -with-rtsopts=-N -fno-ignore-asserts -Wall
+  ghc-options:      -threaded -rtsopts -with-rtsopts=-N -fno-ignore-asserts
   build-depends:
     , base                 >=4.12 && < 5
     , filepath
     , hls-change-type-signature-plugin
     , hls-test-utils       == 2.6.0.0
-    , lsp
-    , QuickCheck
     , regex-tdfa
     , text
   default-extensions:

plugins/hls-change-type-signature-plugin/src/Ide/Plugin/ChangeTypeSignature.hs

@@ -46,7 +46,7 @@ codeActionHandler plId ideState _ CodeActionParams {_textDocument = TextDocument
 getDecls :: MonadIO m => PluginId -> IdeState -> NormalizedFilePath -> ExceptT PluginError m [LHsDecl GhcPs]
 getDecls (PluginId changeTypeSignatureId) state =
     runActionE (T.unpack changeTypeSignatureId <> ".GetParsedModule") state
-    . (fmap (hsmodDecls . unLoc . pm_parsed_source))
+    . fmap (hsmodDecls . unLoc . pm_parsed_source)
     . useE GetParsedModule
 
 -- | Text representing a Declaration's Name

plugins/hls-change-type-signature-plugin/test/Main.hs

@@ -95,8 +95,8 @@ goldenChangeSignature fp = goldenWithHaskellDoc def changeTypeSignaturePlugin (f
 
 codeActionTest :: FilePath -> Int -> Int -> TestTree
 codeActionTest fp line col = goldenChangeSignature fp $ \doc -> do
-    void $ waitForDiagnostics  -- code actions are triggered from Diagnostics
-    void $ waitForAllProgressDone  -- apparently some tests need this to get the CodeAction to show up
+    void waitForDiagnostics  -- code actions are triggered from Diagnostics
+    void waitForAllProgressDone  -- apparently some tests need this to get the CodeAction to show up
     actions <- getCodeActions doc (pointRange line col)
     foundActions <- findChangeTypeActions actions
     liftIO $ length foundActions @?= 1