Missing bounds for `base` break builds with QuicckCheck-2.17.0.0 (and probably more)

getDown was introduced in GHC 8.10 (base-4.14.0.0)

So, I'm getting

src/Test/QuickCheck/Arbitrary.hs:1181:32: error:
    Variable not in scope: getDown :: Down a -> a

with GHC 8.8 and GHC 8.6.

Data.Finctor.Contravariant was introduced in GHC 8.6 (base-4.12.0.0)

So, I'm getting

src/Test/QuickCheck/Arbitrary.hs:218:1: error:
    Could not find module ‘Data.Functor.Contravariant’

with GHC 8.4.

It will also bring problems down the road that transformers, containers, data-array-byte, deepseq, template-haskell are all missing (some) bounds. Also, random is outdated and uses an upper bound with trailing zeroes which is a bad idea, as rightly pointed out by cabal check.

All these issues could be fixed by a Hackage revision.

Start with the compatibility errors in src/Test/QuickCheck/Arbitrary.hs and the package dependency bounds, then run cabal check and the GHC 8.4, 8.6, and 8.8 builds linked in the report. Done means the base and other listed dependency bounds support the intended versions, obsolete random bounds are corrected, and the affected builds pass.