Use data for Signed, Unsigned, Index, and BiSignalOut

GHC may insert coercions making Clash see underlying types. For the
types mentioned in the commit title, this means Clash will see either a
`Natural` or an `Integer`. These types are (for better or for worse)
represented as machine words, potentially truncating any operations. As
a concrete example, take:

    top :: Unsinged 68 -> Unsigned 68 -> Vec 1 (Unsigned 64)
    top x y = let res = x + y in res `seq` res :> Nil

Translated to core, we get:

    λ(x :: Unsigned 68) ->
    λ(y :: Unsigned 68) ->
    let
      nt :: Natural
      = +# @68 topEntity2[GlobalId] x[LocalId]
          y[LocalId]
    in case nt[LocalId] of
         _ ->
           Cons @(+ 0 1) @(Unsigned 68) @0
             (_CO_ @(~# Natural Natural (+ 0 1) (+ 0 1)))
             nt[LocalId]
             ((Λb ->
                Nil @0 @b (_CO_ @(~# Natural Natural 0 0)))
                @(Unsigned 68))

I.e., the result of `x + y` gets assinged to a binder of type `Natural`,
making the calculation truncate.

Author: martijnbastiaan

clash-prelude/src/Clash/Signal/BiSignal.hs

@@ -206,13 +206,8 @@ type role BiSignalOut nominal nominal nominal
 --
 -- as it is not safe to coerce the default behaviour, synthesis domain or width
 -- of the data in the signal.
-#if MIN_VERSION_base(4,15,0) && !MIN_VERSION_base(4,17,0)
 data BiSignalOut (ds :: BiSignalDefault) (dom :: Domain) (n :: Nat)
   = BiSignalOut ![Signal dom (Maybe (BitVector n))]
-#else
-newtype BiSignalOut (ds :: BiSignalDefault) (dom :: Domain) (n :: Nat)
-  = BiSignalOut [Signal dom (Maybe (BitVector n))]
-#endif
 
 type instance HasDomain dom1 (BiSignalOut ds dom2 n) = DomEq dom1 dom2
 type instance TryDomain t (BiSignalOut ds dom n) = 'Found dom

clash-prelude/src/Clash/Sized/Internal/Index.hs

@@ -158,17 +158,10 @@ type role Index nominal
 --
 -- as it is not safe to coerce between 'Index'es with different ranges. To
 -- change the size, use the functions in the 'Resize' class.
-#if MIN_VERSION_base(4,15,0) && !MIN_VERSION_base(4,17,0)
 data Index (n :: Nat) =
     -- | The constructor, 'I', and the field, 'unsafeToInteger', are not
     -- synthesizable.
     I { unsafeToInteger :: !Integer }
-#else
-newtype Index (n :: Nat) =
-    -- | The constructor, 'I', and the field, 'unsafeToInteger', are not
-    -- synthesizable.
-    I { unsafeToInteger :: Integer }
-#endif
   deriving (Data, Generic)
 
 {-# ANN I hasBlackBox #-}

clash-prelude/src/Clash/Sized/Internal/Signed.hs

@@ -184,17 +184,10 @@ type role Signed nominal
 --
 -- as it is not safe to coerce between different width Signed. To change the
 -- width, use the functions in the 'Clash.Class.Resize.Resize' class.
-#if (__GLASGOW_HASKELL__ >= 900 && __GLASGOW_HASKELL__ < 904) || __GLASGOW_HASKELL__ >= 912
 data Signed (n :: Nat) =
     -- | The constructor, 'S', and the field, 'unsafeToInteger', are not
     -- synthesizable.
     S { unsafeToInteger :: !Integer}
-#else
-newtype Signed (n :: Nat) =
-    -- | The constructor, 'S', and the field, 'unsafeToInteger', are not
-    -- synthesizable.
-    S { unsafeToInteger :: Integer}
-#endif
   deriving (Data, Generic)
 
 {-# ANN S hasBlackBox #-}

clash-prelude/src/Clash/Sized/Internal/Unsigned.hs

@@ -200,17 +200,10 @@ type role Unsigned nominal
 --
 -- as it is not safe to coerce between different width Unsigned. To change the
 -- width, use the functions in the 'Clash.Class.Resize.Resize' class.
-#if (__GLASGOW_HASKELL__ >= 900 && __GLASGOW_HASKELL__ < 904) || __GLASGOW_HASKELL__ >= 912
 data Unsigned (n :: Nat) =
     -- | The constructor, 'U', and the field, 'unsafeToNatural', are not
     -- synthesizable.
     U { unsafeToNatural :: !Natural }
-#else
-newtype Unsigned (n :: Nat) =
-    -- | The constructor, 'U', and the field, 'unsafeToNatural', are not
-    -- synthesizable.
-    U { unsafeToNatural :: Natural }
-#endif
   deriving (Data, Generic)
 
 {-# ANN U hasBlackBox #-}