File in question: https://gitlab.com/krakrjak/icfp2020-junkfood/-/blob/8704f0958a118a94ab21538a5ce4ee07b9b74f8f/src/Junkfood/Cmdline.hs
stack "Version 2.3.1 x86_64 hpack-0.33.0" and GHC "The Glorious Glasgow Haskell Compilation System, version 8.8.3" everything builds fine, but stylish can't parse it.
I tried moving things around a bit, but didn't immediately find some changes to work around the parse failure, either.