ConstPtr.hs

{-# LANGUAGE CPP #-}

module Botan.Bindings.ConstPtr (
    ConstPtr(..)
  ) where

#if MIN_VERSION_base (4,18,0)
import           Foreign.C.ConstPtr
#else
import           Data.Data
import           Data.Kind
import           Foreign.Ptr
import           Foreign.Storable
#endif

#if !(MIN_VERSION_base (4,18,0))

-- NOTE: Taken from Foreign.C.ConstPtr, more or less
-- NOTE: Raises a warning on older base / compilers if the shim
--       is a `newtype` instead of a `type`, because the special
--       logic for const pointers didn't exist yet
-- SEE: https://gitlab.haskell.org/ghc/ghc/-/issues/22043
-- AFFECTS:
--  botan_error_description
--  botan_error_last_exception_message
--  botan_x509_cert_validation_status
--  botan_version_string
type ConstPtr :: Type -> Type
type role ConstPtr phantom
newtype ConstPtr a = ConstPtr { unConstPtr :: Ptr a }
    deriving stock (Data)
    deriving newtype (Eq, Ord, Storable)

instance Show (ConstPtr a) where
    showsPrec d (ConstPtr p) = showParen (d > 10) $ showString "ConstPtr " . showsPrec 11 p

#endif