Fix building with older ghc

Should work with 6.10 to 7.10

Author: dcoutts

Codec/Compression/Zlib/Internal.hs

@@ -1,5 +1,7 @@
 {-# LANGUAGE CPP, RankNTypes, DeriveDataTypeable, BangPatterns #-}
+#if __GLASGOW_HASKELL__ >= 702
 {-# LANGUAGE Trustworthy #-}
+#endif
 -----------------------------------------------------------------------------
 -- |
 -- Copyright   :  (c) 2006-2014 Duncan Coutts

Codec/Compression/Zlib/Stream.hsc

@@ -1,4 +1,7 @@
-{-# LANGUAGE ForeignFunctionInterface, DeriveDataTypeable, DeriveGeneric #-}
+{-# LANGUAGE CPP, ForeignFunctionInterface, DeriveDataTypeable #-}
+#if __GLASGOW_HASKELL__ >= 702
+{-# LANGUAGE DeriveGeneric #-}
+#endif
 -----------------------------------------------------------------------------
 -- |
 -- Copyright   :  (c) 2006-2014 Duncan Coutts
@@ -119,7 +122,9 @@ import Control.Monad.ST.Strict
 #endif
 import Control.Exception (assert)
 import Data.Typeable (Typeable)
+#if __GLASGOW_HASKELL__ >= 702
 import GHC.Generics (Generic)
+#endif
 #ifdef DEBUG
 import System.IO (hPutStrLn, stderr)
 #endif
@@ -565,7 +570,11 @@ fromFlush Finish    = #{const Z_FINISH}
 -- variations.
 --
 data Format = GZip | Zlib | Raw | GZipOrZlib
-  deriving (Eq, Ord, Enum, Bounded, Show, Typeable, Generic)
+  deriving (Eq, Ord, Enum, Bounded, Show, Typeable
+#if __GLASGOW_HASKELL__ >= 702
+              , Generic
+#endif
+           )
 
 {-# DEPRECATED GZip       "Use gzipFormat. Format constructors will be hidden in version 0.7"       #-}
 {-# DEPRECATED Zlib       "Use zlibFormat. Format constructors will be hidden in version 0.7"       #-}
@@ -610,7 +619,11 @@ formatSupportsDictionary _    = False
 -- | The compression method
 --
 data Method = Deflated
-  deriving (Eq, Ord, Enum, Bounded, Show, Typeable, Generic)
+  deriving (Eq, Ord, Enum, Bounded, Show, Typeable
+#if __GLASGOW_HASKELL__ >= 702
+              , Generic
+#endif
+           )
 
 {-# DEPRECATED Deflated "Use deflateMethod. Method constructors will be hidden in version 0.7" #-}
 
@@ -634,7 +647,11 @@ data CompressionLevel =
   | BestSpeed
   | BestCompression
   | CompressionLevel Int
-  deriving (Eq, Show, Typeable, Generic)
+  deriving (Eq, Show, Typeable
+#if __GLASGOW_HASKELL__ >= 702
+              , Generic
+#endif
+           )
 
 {-# DEPRECATED DefaultCompression "Use defaultCompression. CompressionLevel constructors will be hidden in version 0.7" #-}
 {-# DEPRECATED NoCompression      "Use noCompression. CompressionLevel constructors will be hidden in version 0.7"      #-}
@@ -694,7 +711,11 @@ data WindowBits = WindowBits Int
                                     -- is defined with and used by the tests.
                                     -- It makse sense because the default value
                                     -- is is also the max value at 15.
-  deriving (Eq, Show, Typeable, Generic)
+  deriving (Eq, Show, Typeable
+#if __GLASGOW_HASKELL__ >= 702
+              , Generic
+#endif
+           )
 
 {-# DEPRECATED DefaultWindowBits  "Use defaultWindowBits. WindowBits constructors will be hidden in version 0.7" #-}
 --FIXME: cannot deprecate constructor named the same as the type
@@ -750,7 +771,11 @@ data MemoryLevel =
   | MinMemoryLevel
   | MaxMemoryLevel
   | MemoryLevel Int
-  deriving (Eq, Show, Typeable, Generic)
+  deriving (Eq, Show, Typeable
+#if __GLASGOW_HASKELL__ >= 702
+              , Generic
+#endif
+           )
 
 {-# DEPRECATED DefaultMemoryLevel "Use defaultMemoryLevel. MemoryLevel constructors will be hidden in version 0.7" #-}
 {-# DEPRECATED MinMemoryLevel     "Use minMemoryLevel. MemoryLevel constructors will be hidden in version 0.7"     #-}
@@ -800,7 +825,11 @@ data CompressionStrategy =
     DefaultStrategy
   | Filtered
   | HuffmanOnly
-  deriving (Eq, Ord, Enum, Bounded, Show, Typeable, Generic)
+  deriving (Eq, Ord, Enum, Bounded, Show, Typeable
+#if __GLASGOW_HASKELL__ >= 702
+              , Generic
+#endif
+           )
 
 {-
 -- -- only available in zlib 1.2 and later, uncomment if you need it.

zlib.cabal

@@ -43,9 +43,13 @@ library
   else
     default-language: Haskell2010
   other-extensions: CPP, ForeignFunctionInterface, RankNTypes, BangPatterns,
-                    DeriveDataTypeable, DeriveGeneric
-  build-depends:   base >= 3 && < 5,
+                    DeriveDataTypeable
+  if impl(ghc >= 7.2)
+    other-extensions: DeriveGeneric
+  build-depends:   base >= 4 && < 5,
                    bytestring >= 0.9 && < 0.12
+  if impl(ghc >= 7.2 && < 7.6)
+    build-depends: ghc-prim
   includes:        zlib.h
   ghc-options:     -Wall -fwarn-tabs
   if !os(windows)