[commit: packages/bytestring] ghc-head: Remove dubious and unnecessary use of unsafeCoerce (4cc37e8)

[git at git.haskell.org]

Repository : ssh://git at git.haskell.org/bytestring

On branch  : ghc-head
Link       : http://git.haskell.org/packages/bytestring.git/commitdiff/4cc37e85c8f4718907c9888f75666d7dd0dd4f1a

>---------------------------------------------------------------

commit 4cc37e85c8f4718907c9888f75666d7dd0dd4f1a
Author: Duncan Coutts <duncan at community.haskell.org>
Date:   Thu Oct 3 21:25:21 2013 +0100

    Remove dubious and unnecessary use of unsafeCoerce
    
    It's not needed to implement Float -> Word32.
    Also, include the name of tests in testBoundedProperty.


>---------------------------------------------------------------

4cc37e85c8f4718907c9888f75666d7dd0dd4f1a
 .../Data/ByteString/Builder/Prim/TestUtils.hs      |   27 +++++---------------
 1 file changed, 7 insertions(+), 20 deletions(-)

diff --git a/tests/builder/Data/ByteString/Builder/Prim/TestUtils.hs b/tests/builder/Data/ByteString/Builder/Prim/TestUtils.hs
index 02b7d5f..8d93262 100644
--- a/tests/builder/Data/ByteString/Builder/Prim/TestUtils.hs
+++ b/tests/builder/Data/ByteString/Builder/Prim/TestUtils.hs
@@ -82,7 +82,6 @@ import Foreign
 #endif
 
 import           System.ByteOrder
-import           Unsafe.Coerce (unsafeCoerce)
 
 #if defined(HAVE_TEST_FRAMEWORK)
 import           Test.HUnit (assertBool)
@@ -102,9 +101,9 @@ import           Test.QuickCheck (Arbitrary(..))
 testBoundedProperty :: forall a. (Arbitrary a, Show a, Bounded a)
                     => String -> (a -> Bool) -> Test
 testBoundedProperty name p = testGroup name
-  [ testProperty "arbitrary" p
-  , testCase "minBound" $ assertBool "minBound" (p (minBound :: a))
-  , testCase "maxBound" $ assertBool "minBound" (p (maxBound :: a))
+  [ testProperty name p
+  , testCase (name ++ " minBound") $ assertBool "minBound" (p (minBound :: a))
+  , testCase (name ++ " maxBound") $ assertBool "minBound" (p (maxBound :: a))
   ]
 
 -- | Quote a 'String' nicely.
@@ -355,27 +354,15 @@ float_list f  = f . coerceFloatToWord32
 double_list :: (Word64 -> [Word8]) -> Double -> [Word8]
 double_list f = f . coerceDoubleToWord64
 
--- Note that the following use of unsafeCoerce is not guaranteed to be
--- safe on GHC 7.0 and less. The reason is probably the following ticket:
---
---   http://hackage.haskell.org/trac/ghc/ticket/4092
---
--- However, that only applies if the value is loaded in a register. We
--- avoid this by coercing only boxed values and ensuring that they
--- remain boxed using a NOINLINE pragma.
---
-
--- | Super unsafe coerce a 'Float' to a 'Word32'. We have to explicitly mask
--- out the higher bits in case we are working on a 64-bit machine.
+-- | Convert a 'Float' to a 'Word32'.
 {-# NOINLINE coerceFloatToWord32 #-}
 coerceFloatToWord32 :: Float -> Word32
-coerceFloatToWord32 = (.&. maxBound) . unsafeCoerce
+coerceFloatToWord32 x = unsafePerformIO (with x (peek . castPtr))
 
--- | Super unsafe coerce a 'Double' to a 'Word64'. Currently, there are no
--- > 64 bit machines supported by GHC. But we just play it safe.
+-- | Convert a 'Double' to a 'Word64'.
 {-# NOINLINE coerceDoubleToWord64 #-}
 coerceDoubleToWord64 :: Double -> Word64
-coerceDoubleToWord64 = (.&. maxBound) . unsafeCoerce
+coerceDoubleToWord64 x = unsafePerformIO (with x (peek . castPtr))
 
 -- | Parse a variable length encoding
 parseVar :: (Num a, Bits a) => [Word8] -> (a, [Word8])