Move Void to GHC.Base...

This change would allow `Void` to be used deeper in module graph.
For example exported from `Prelude` (though that might be already
possible).

Also this change includes a change `stimes @Void _ x = x`,
https://github.com/haskell/core-libraries-committee/issues/95

While the above is not required, maintaining old stimes behavior
would be tricky as `GHC.Base` doesn't know about `Num` or `Integral`,
which would require more hs-boot files.

2 files changed, 5 insertions, 66 deletions

diff --git a/libraries/base/Data/Data.hs b/libraries/base/Data/Data.hs
index 4ef7d00d03..b6102d4cf3 100644
--- a/libraries/base/Data/Data.hs
+++ b/libraries/base/Data/Data.hs
@@ -1187,6 +1187,9 @@ deriving instance Data Ordering
 -- | @since 4.0.0.0
 deriving instance (Data a, Data b) => Data (Either a b)
 
+-- | @since 4.8.0.0
+deriving instance Data Void
+
 -- | @since 4.0.0.0
 deriving instance Data ()
 
diff --git a/libraries/base/Data/Void.hs b/libraries/base/Data/Void.hs
index 299b4c78bf..226a9ad994 100644
--- a/libraries/base/Data/Void.hs
+++ b/libraries/base/Data/Void.hs
@@ -1,8 +1,4 @@
-{-# LANGUAGE DeriveDataTypeable #-}
-{-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE EmptyCase #-}
-{-# LANGUAGE EmptyDataDeriving #-}
-{-# LANGUAGE Safe #-}
+{-# LANGUAGE Trustworthy #-}
 
 -----------------------------------------------------------------------------
 -- |
@@ -24,64 +20,4 @@ module Data.Void
     , vacuous
     ) where
 
-import Control.Exception
-import Data.Data
-import Data.Ix
-import GHC.Generics
-import Data.Semigroup (Semigroup(..), stimesIdempotent)
-
--- $setup
--- >>> import Prelude
-
--- | Uninhabited data type
---
--- @since 4.8.0.0
-data Void deriving
-  ( Eq      -- ^ @since 4.8.0.0
-  , Data    -- ^ @since 4.8.0.0
-  , Generic -- ^ @since 4.8.0.0
-  , Ord     -- ^ @since 4.8.0.0
-  , Read    -- ^ Reading a 'Void' value is always a parse error, considering
-            -- 'Void' as a data type with no constructors.
-            --
-            -- @since 4.8.0.0
-  , Show    -- ^ @since 4.8.0.0
-  )
-
--- | @since 4.8.0.0
-instance Ix Void where
-    range _     = []
-    index _     = absurd
-    inRange _   = absurd
-    rangeSize _ = 0
-
--- | @since 4.8.0.0
-instance Exception Void
-
--- | @since 4.9.0.0
-instance Semigroup Void where
-    a <> _ = a
-    stimes = stimesIdempotent
-
--- | Since 'Void' values logically don't exist, this witnesses the
--- logical reasoning tool of \"ex falso quodlibet\".
---
--- >>> let x :: Either Void Int; x = Right 5
--- >>> :{
--- case x of
---     Right r -> r
---     Left l  -> absurd l
--- :}
--- 5
---
--- @since 4.8.0.0
-absurd :: Void -> a
-absurd a = case a of {}
-
--- | If 'Void' is uninhabited then any 'Functor' that holds only
--- values of type 'Void' is holding no values.
--- It is implemented in terms of @fmap absurd@.
---
--- @since 4.8.0.0
-vacuous :: Functor f => f Void -> f a
-vacuous = fmap absurd
+import GHC.Base (Void, absurd, vacuous)