Shim out writeCharArray# when bounds checking is on

bytebuild.cabal

@@ -45,6 +45,7 @@ library
     Data.Bytes.Builder.Bounded.Unsafe
   other-modules:
     Compat
+    Op
   reexported-modules:
     Data.Bytes.Chunks
   build-depends:
@@ -68,8 +69,10 @@ library
       hs-source-dirs: src-9.0
   if flag(checked)
     build-depends: primitive-checked >= 0.7 && <0.8
+    hs-source-dirs: src-checked
   else
     build-depends: primitive >= 0.7 && <0.8
+    hs-source-dirs: src-unchecked
   ghc-options: -Wall -O2
   hs-source-dirs: src
   default-language: Haskell2010

src-checked/Op.hs

@@ -1,8 +1,12 @@
+{-# language MagicHash #-}
+{-# language UnboxedTuples #-}
+
 module Op
   ( writeCharArray#
   ) where
 
 import GHC.Exts ((<#),(>=#))
+import GHC.Int (Int(I#))
 import qualified GHC.Exts as Exts
 
 writeCharArray# :: Exts.MutableByteArray# s -> Exts.Int# -> Exts.Char# -> Exts.State# s -> Exts.State# s 
@@ -11,4 +15,4 @@ writeCharArray# arr i v st = case i <# 0# of
   _ -> case Exts.getSizeofMutableByteArray# arr st of
     (# st', sz #) -> case i >=# sz of
       1# -> error ("writeCharArray#: index " ++ show (I# i) ++ " >= length " ++ show (I# sz))
-      _ -> Exts.writeInt8Array# arr i (Exts.intToInt8# v) st'
+      _ -> Exts.writeCharArray# arr i v st'

src-unchecked/Op.hs

@@ -1,3 +1,5 @@
+{-# language MagicHash #-}
+
 module Op
   ( writeCharArray#
   ) where