Add the ExtendedLiterals extension

(cherry picked from commit 6c720dd8)

Cabal-syntax/src/Language/Haskell/Extension.hs

@@ -677,6 +677,9 @@ data KnownExtension =
   -- | Enable data types for which an unlifted or levity-polymorphic result kind is inferred.
   | UnliftedDatatypes
 
+  | -- | Enable syntax for primitive numeric literals, e.g. @3#Int8@
+    ExtendedLiterals
+
   -- | Enable syntax for primitive numeric literals, e.g. @3#Int8@
   | ExtendedLiterals
 

editors/vim/syntax/cabal.vim

@@ -181,6 +181,7 @@ syn keyword cabalExtension contained
   \ ExplicitForAll
   \ ExplicitNamespaces
   \ ExtendedDefaultRules
+  \ ExtendedLiterals
   \ ExtensibleRecords
   \ ExtendedLiterals
   \ FieldSelectors