$ ghc-stage2 --version
The Glorious Glasgow Haskell Compilation System, version 9.3.20210608

$ cabal build --with-compiler ghc-stage2 --allow-newer

Data/Colour/CIE.hs:80:12: error:
    Ambiguous occurrence ‘sum’
    It could refer to
       either ‘Prelude.sum’,
              imported from ‘Prelude’ at Data/Colour/CIE.hs:25:8-22
              (and originally defined in ‘Data.Foldable’)
           or ‘Data.List.sum’,
              imported from ‘Data.List’ at Data/Colour/CIE.hs:41:1-16
              (and originally defined in ‘GHC.List’)
   |
80 |    total = sum $ map fst l