Add To/FromJSONKey Void instances

Author: phadej

changelog.md

@@ -4,6 +4,7 @@ For the latest version of this document, please see [https://github.com/haskell/
 
 * Support deriving for empty datatypes (such as `Void` and `V1`)
   in `FromJSON` and `ToJSON`.
+* Add `To/FromJSONKey Void` instances
 
 ### 2.1.1.0
 

src/Data/Aeson/Types/FromJSON.hs

@@ -1542,6 +1542,10 @@ instance (FromJSON a, FromJSON b) => FromJSON (Either a b) where
 instance FromJSON Void where
     parseJSON _ = fail "Cannot parse Void"
 
+-- | @since 2.1.2.0
+instance FromJSONKey Void where
+    fromJSONKey = FromJSONKeyTextParser $ \_ -> fail "Cannot parse Void"
+
 instance FromJSON Bool where
     parseJSON (Bool b) = pure b
     parseJSON v = typeMismatch "Bool" v

src/Data/Aeson/Types/ToJSON.hs

@@ -1313,6 +1313,10 @@ instance ToJSON Void where
     toJSON = absurd
     toEncoding = absurd
 
+-- | @since 2.1.2.0
+instance ToJSONKey Void where
+    toJSONKey = ToJSONKeyText absurd absurd
+
 instance ToJSON Bool where
     toJSON = Bool
     toEncoding = E.bool