Remove Strict from the language extensions used for code actions

Since the code action for language extension suggestions uses substring
matching, the presence of the literal name of an extension can trigger
a false positive.

`Strict` is an identifier that occurs frequently in imports, causing
the extension to be suggested rather than the removal of a redundant
import.

src/Development/IDE/Plugin/CodeAction.hs

@@ -266,7 +266,9 @@ suggestAddExtension Diagnostic{_range=_range,..}
 
 -- | All the GHC extensions
 ghcExtensions :: Map.HashMap T.Text Extension
-ghcExtensions = Map.fromList . map ( ( T.pack . flagSpecName ) &&& flagSpecFlag ) $ xFlags
+ghcExtensions = Map.fromList . filter notStrictFlag . map ( ( T.pack . flagSpecName ) &&& flagSpecFlag ) $ xFlags
+  where
+    notStrictFlag (name, _) = name /= "Strict"
 
 suggestModuleTypo :: Diagnostic -> [(T.Text, [TextEdit])]
 suggestModuleTypo Diagnostic{_range=_range,..}

test/exe/Main.hs

@@ -818,6 +818,28 @@ removeImportTests = testGroup "remove import actions"
             , "main = B"
             ]
       liftIO $ expectedContentAfterAction @=? contentAfterAction
+  , testSession "import containing the identifier Strict" $ do
+      let contentA = T.unlines
+            [ "module Strict where"
+            ]
+      _docA <- createDoc "Strict.hs" "haskell" contentA
+      let contentB = T.unlines
+            [ "{-# OPTIONS_GHC -Wunused-imports #-}"
+            , "module ModuleB where"
+            , "import Strict"
+            ]
+      docB <- createDoc "ModuleB.hs" "haskell" contentB
+      _ <- waitForDiagnostics
+      [CACodeAction action@CodeAction { _title = actionTitle }]
+          <- getCodeActions docB (Range (Position 2 0) (Position 2 5))
+      liftIO $ "Remove import" @=? actionTitle
+      executeCodeAction action
+      contentAfterAction <- documentContents docB
+      let expectedContentAfterAction = T.unlines
+            [ "{-# OPTIONS_GHC -Wunused-imports #-}"
+            , "module ModuleB where"
+            ]
+      liftIO $ expectedContentAfterAction @=? contentAfterAction
   ]
 
 extendImportTests :: TestTree