`Natural` is not exported from `clash-prelude-1.9.0`'s `Clash.Prelude` GHC 9.0.2 (and lower?)

[lmbollen]

Found on the clash-vexriscv repo:
https://github.com/clash-lang/clash-vexriscv/actions/runs/8615733120/job/23611920320
9.2.8 and 9.4.8 do pass.
9.0.2:

 [4 of 8] Compiling VexRiscv.Random  ( src/VexRiscv/Random.hs, /__w/clash-vexriscv/clash-vexriscv/dist-newstyle/build/x86_64-linux/ghc-9.0.2/clash-vexriscv-0.1/build/VexRiscv/Random.o, /__w/clash-vexriscv/clash-vexriscv/dist-newstyle/build/x86_64-linux/ghc-9.0.2/clash-vexriscv-0.1/build/VexRiscv/Random.dyn_o )

src/VexRiscv/Random.hs:42:16: error:
    Not in scope: type constructor or class ‘Natural’
   |
42 | genNatural :: (Natural, Natural) -> IO Natural
   |                ^^^^^^^

src/VexRiscv/Random.hs:42:25: error:
    Not in scope: type constructor or class ‘Natural’
   |
42 | genNatural :: (Natural, Natural) -> IO Natural
   |                         ^^^^^^^

src/VexRiscv/Random.hs:42:40: error:
    Not in scope: type constructor or class ‘Natural’
   |
42 | genNatural :: (Natural, Natural) -> IO Natural
   |                                        ^^^^^^^
Error: cabal: Failed to build clash-vexriscv-0.1.

Error: Process completed with exit code 1.

[DigitalBrains1]

Ah, we get that as a stray export from GHC.TypeLits. I'm not sure it's even supposed to be exported from our Prelude, but we do

clash-compiler/clash-prelude/src/Clash/Prelude.hs

Line 139 in a26bb9e

, module GHC.TypeLits

so we get that. The risks of exporting modules you don't control!

[leonschoorl]

We're reexporting a lot of things from GHC.TypeLits that we probably shouldn't.
For example since GHC-9.6 this includes: natSing :: KnownNat n => GHC.TypeNats.SNat n
Which uses a SNat that's different from clash-prelude's own Clash.Promoted.Nat.SNat.

[DigitalBrains1]

Fixing any of this is an API change, though :-(