Simple design fails to compile

[adamwalker]

Using Clash 0.99.3, compilation of the design below fails with the error:

<no location info>: error:
    Clash error call:
    Clash.Normalize(189): Expr belonging to bndr: x1536 not found

module Mod where

import Clash.Prelude

func
    :: BitVector 8
    -> BitVector 8
    -> BitVector 32
func d c
    | c == 0    = resize d
    | otherwise = 0

mod'
    :: forall dom gated sync. HiddenClockReset dom gated sync
    => Signal dom (BitVector 32)
mod' = o
    where

    x :: Signal dom (BitVector 8) = pure 0 
    y :: Signal dom (BitVector 8) = (+1) <$> z
    z :: Signal dom (BitVector 8) = pure 0

    f :: Signal dom (BitVector 8) -> Signal dom (BitVector 32)
    f = foldl1 (\x y o -> liftA2 (.|.) (x o) (y o)) 
        $  liftA2 func x
        :> liftA2 func y
        :> liftA2 func z
        :> Nil

    o = f (pure 0)

topEntity clk rst = withClockReset @System @Source @Synchronous clk rst mod'

[Jhana1]

I think there's something broken with resize
See #352

[adamwalker]

I'm not sure. If I remove the resize the bug is still there.

[leonschoorl]

So far I've reduced the test case to this:

module Mod where

import Clash.Prelude

func
    :: BitVector 8
    -> BitVector 8
    -> BitVector 32
func d c = 0

mod'
    :: forall dom gated sync. HiddenClockReset dom gated sync
    => Signal dom (BitVector 32)
mod' = o
    where

    x :: Signal dom (BitVector 8) = pure 0

    f :: Signal dom (BitVector 8) -> Signal dom (BitVector 32)
    f = foldl1 (\x y q -> liftA2 (.|.) (x q) (y q))
        $  liftA2 func x
        :> liftA2 func x
        :> liftA2 func x
        :> Nil

    o :: Signal dom (BitVector 32)
    o = f (pure 0)

topEntity clk rst = withClockReset @System @Source @Synchronous clk rst mod'

There seems to be something weird going on in Clash.Core.Evaluator during a caseCon transformation. (Adding -fclash-debug DebugApplied will make it complain about free variables being added)

It seems to add a reference to this x1536 but forgets to add the actual binding.

I'll dig some further tomorrow