[test] add more tests

t/basics.hs

@@ -1,4 +1,6 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE DeriveGeneric #-}
 
 import Data.Default
 import Data.Int
@@ -11,6 +13,16 @@ import qualified Data.Set as S
 import qualified Data.IntMap as IM
 import qualified Data.IntSet as IS
 import Data.Tree (Tree(..))
+import Data.Functor.Identity
+import Control.Applicative
+import Data.Proxy
+import Data.Tuple
+import GHC.Generics
+import Foreign.C.Types
+import Foreign.Ptr
+#if MIN_VERSION_base(4, 18, 0)
+import Foreign.C.ConstPtr
+#endif
 
 import Control.Monad (when)
 import Control.Monad.Reader
@@ -54,9 +66,17 @@ is    x y = ok (x == y) (show x ++ " == " ++ show y)
 -- diag s = liftIO $ do
 --     putStrLn $ "# " ++ s
 
+data T0 a b
+    = C0 a a
+    | C1
+    | C2 b
+    deriving (Eq, Show, Generic)
+
+instance (Default a) => Default (T0 a b)
+
 main :: IO ()
 main = runTest $ do
-    planTests 35
+    planTests 66
     is def ()
     is def (Nothing :: Maybe (Int, Ordering, [Float]))
     is def ""
@@ -73,6 +93,13 @@ main = runTest $ do
     is def (First Nothing :: First ())
     is def (Sum (0 :: Integer))
     is def (Product (1 :: Rational))
+    is def (Identity ())
+    is def (Const 0 :: Const Int Char)
+    is def (Proxy :: Proxy Char)
+#if MIN_VERSION_base(4, 16, 0)
+    is def (pure () :: Solo ())
+#endif
+    is def False
     is def (0 :: Int)
     is def (0 :: Integer)
     is def (0 :: Float)
@@ -88,7 +115,39 @@ main = runTest $ do
     is def (0 :: Word16)
     is def (0 :: Word32)
     is def (0 :: Word64)
+    is def (0 :: CShort)
+    is def (0 :: CUShort)
+    is def (0 :: CInt)
+    is def (0 :: CUInt)
+    is def (0 :: CLong)
+    is def (0 :: CULong)
+    is def (0 :: CLLong)
+    is def (0 :: CULLong)
+    is def (0 :: CPtrdiff)
+    is def (0 :: CSize)
+    is def (0 :: CSigAtomic)
+    is def (0 :: CIntPtr)
+    is def (0 :: CUIntPtr)
+    is def (0 :: CIntMax)
+    is def (0 :: CUIntMax)
+    is def (0 :: CClock)
+    is def (0 :: CTime)
+    is def (0 :: CUSeconds)
+    is def (0 :: CSUSeconds)
+    is def (0 :: CFloat)
+    is def (0 :: CDouble)
+    is def (0 :: IntPtr)
+    is def (0 :: WordPtr)
+#if MIN_VERSION_base(4, 10, 0)
+    is def (0 :: CBool)
+#endif
+    is def nullPtr
+    is def nullFunPtr
+#if MIN_VERSION_base(4, 18, 0)
+    is def (ConstPtr nullPtr)
+#endif
     is def ((def, def) :: ((), Maybe ((), ())))
     is def ((def, def, def) :: ((), Maybe ((), ()), [Ordering]))
     is def ((def, def, def, def) :: ((), Maybe ((), ()), [Ordering], Float))
     is def ((def, def, def, def, def, def, def) :: ((), (), (), (), (), (), ()))
+    is def (C0 0 0 :: T0 Int Char)