-Wtype-equality-out-of-scope for use type equality (GHC 9.10)

[andreasabel]

There is a new warning with GHC 9.10:

src/WithIndex.hs:264:27: warning: [GHC-12003] [-Wtype-equality-out-of-scope]
    • The ‘~’ operator is out of scope.
      Assuming it to stand for an equality constraint.
    • NB: ‘~’ used to be built-in syntax but now is a regular type operator
          exported from Data.Type.Equality and Prelude.
      If you are using a custom Prelude, consider re-exporting it.
    • This will become an error in a future GHC release.
    |
264 |   default itraverse :: (i ~ Int, Applicative f) => (i -> a -> f b) -> t a -> f (t b)
    |            

[phadej]

It's a warning. Won't fix until it's an issue.

I'll remove ghc-options: -Wall from the .cabal file (and move it to cabal.project), so you won't see it when building your dependencies.