1 files changed, 47 insertions, 0 deletions
diff --git a/testsuite/tests/ffi/should_run/UnliftedNewtypesByteArrayOffset.hs b/testsuite/tests/ffi/should_run/UnliftedNewtypesByteArrayOffset.hs
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+++ b/testsuite/tests/ffi/should_run/UnliftedNewtypesByteArrayOffset.hs
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+{-# language ForeignFunctionInterface #-}
+{-# language GADTSyntax #-}
+{-# language KindSignatures #-}
+{-# language MagicHash #-}
+{-# language UnboxedTuples #-}
+{-# language UnliftedFFITypes #-}
+{-# language UnliftedNewtypes #-}
+
+{-# OPTIONS_GHC -O2 #-}
+
+import Data.Kind (Type)
+import Data.Word
+import GHC.Exts
+import GHC.IO
+import GHC.Word
+
+foreign import ccall unsafe "head_bytearray"
+  c_head_bytearray_a :: MutableByteArray# RealWorld -> IO Word8
+foreign import ccall unsafe "head_bytearray"
+  c_head_bytearray_b :: MyArray# -> IO Word8
+
+newtype MyArray# :: TYPE 'UnliftedRep where
+  MyArray# :: MutableByteArray# RealWorld -> MyArray#
+
+data MutableByteArray :: Type where
+  MutableByteArray :: MutableByteArray# RealWorld -> MutableByteArray
+
+main :: IO ()
+main = do
+  ba@(MutableByteArray ba#) <- luckySingleton
+  print =<< readByteArray ba 0
+  print =<< c_head_bytearray_a ba#
+  print =<< c_head_bytearray_b (MyArray# ba#)
+
+readByteArray :: MutableByteArray -> Int -> IO Word8
+readByteArray (MutableByteArray b#) (I# i#) = IO $ \s0 ->
+  case readWord8Array# b# i# s0 of
+    (# s1, w #) -> (# s1, W8# w #)
+
+-- Create a new mutable byte array of length 1 with the sole byte
+-- set to the 105.
+luckySingleton :: IO MutableByteArray
+luckySingleton = IO $ \s0 -> case newByteArray# 1# s0 of
+  (# s1, marr# #) -> case writeWord8Array# marr# 0# 105## s1 of
+    s2 -> (# s2, MutableByteArray marr# #)
+
+