From a24c404444eef117a25bf247ca86312f107dd124 Mon Sep 17 00:00:00 2001
From: Poscat <poscat@mail.poscat.moe>
Date: Tue, 19 Jan 2021 23:05:07 +0800
Subject: [PATCH] Fix compatibility with older ghc versions

---
 Data/Aeson/Types/FromJSON.hs | 17 ++++++++---------
 Data/Aeson/Types/ToJSON.hs   |  2 +-
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/Data/Aeson/Types/FromJSON.hs b/Data/Aeson/Types/FromJSON.hs
index b4c65fe78..363b17a66 100644
--- a/Data/Aeson/Types/FromJSON.hs
+++ b/Data/Aeson/Types/FromJSON.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE DefaultSignatures #-}
@@ -10,7 +11,6 @@
 {-# LANGUAGE PolyKinds #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE TupleSections #-}
 {-# LANGUAGE UndecidableInstances #-}
@@ -159,8 +159,7 @@ import qualified Data.Primitive.Types as PM
 import qualified Data.Primitive.PrimArray as PM
 
 import Data.Coerce (Coercible, coerce)
-import GHC.TypeNats
-import Data.Kind (Type)
+import GHC.TypeLits
 
 parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
 parseIndexedJSON p idx value = p value <?> Index idx
@@ -1435,11 +1434,11 @@ instance ( IsRecord f isRecord
          , Constructor c
          ) => FromTaggedFlatObject arity (C1 c f) where
     parseTaggedFlatObject (tag :* p@(_ :* opts :* _)) obj
-       | tag == tag' = Just $ fmap M1 $ (unTagged @Type @isRecord) $ parseTaggedFlatObject' (cname :* p) obj
+       | tag == tag' = Just $ fmap M1 $ (unTagged :: Tagged isRecord _ -> _) $ parseTaggedFlatObject' (cname :* p) obj
        | otherwise = Nothing
      where
         tag' = pack $ constructorTagModifier opts cname
-        cname = conName (undefined :: M1 i c a p)
+        cname = conName (undefined :: M1 i c f p)
 
 class FromTaggedFlatObject' arity f isRecord where
     parseTaggedFlatObject' :: ConName :* TypeName :* Options :* FromArgs arity a
@@ -1453,7 +1452,7 @@ instance FromTaggedFlatObject' arity U1 False where
     parseTaggedFlatObject' _ _ = Tagged (pure U1)
 
 instance OVERLAPPABLE_ (PositionFromObject 1 arity f) => FromTaggedFlatObject' arity f False where
-    parseTaggedFlatObject' (_ :* p) obj = Tagged (positionFromObject (Proxy @1) p obj)
+    parseTaggedFlatObject' (_ :* p) obj = Tagged (positionFromObject (Proxy :: Proxy 1) p obj)
  
 class KnownNat n => PositionFromObject n arity f where
     positionFromObject :: Proxy n
@@ -1463,15 +1462,15 @@ class KnownNat n => PositionFromObject n arity f where
 
 instance (KnownNat n, GFromJSON arity a) => PositionFromObject n arity (S1 m a) where
     positionFromObject _ (_ :* opts :* fargs) obj =
-       explicitParseField (gParseJSON opts fargs) obj $ pack $ show $ natVal $ Proxy @n
+       explicitParseField (gParseJSON opts fargs) obj $ pack $ show $ natVal (Proxy :: Proxy n)
 
 instance ( PositionFromObject n arity f
          , PositionFromObject (n+1) arity g
          ) => PositionFromObject n arity (f :*: g) where
     positionFromObject _ p obj =
       (:*:)
-        <$> positionFromObject (Proxy @n) p obj
-        <*> positionFromObject (Proxy @(n+1)) p obj
+        <$> positionFromObject (Proxy :: Proxy n) p obj
+        <*> positionFromObject (Proxy :: Proxy (n+1)) p obj
 
 --------------------------------------------------------------------------------
 
diff --git a/Data/Aeson/Types/ToJSON.hs b/Data/Aeson/Types/ToJSON.hs
index bf791e74e..5f9c09d69 100644
--- a/Data/Aeson/Types/ToJSON.hs
+++ b/Data/Aeson/Types/ToJSON.hs
@@ -142,7 +142,7 @@ import qualified Data.Primitive.Array as PM
 import qualified Data.Primitive.SmallArray as PM
 import qualified Data.Primitive.Types as PM
 import qualified Data.Primitive.PrimArray as PM
-import GHC.TypeNats
+import GHC.TypeLits
 
 toJSONPair :: (a -> Value) -> (b -> Value) -> (a, b) -> Value
 toJSONPair a b = liftToJSON2 a (listValue a) b (listValue b)