[bug#39309] [PATCH WIP] gnu: add stack.

[John Soo]

Hi Tim,

> At this point, it might be worth joining the Nix folks on that issue,
> and suggesting a patch to Cabal to call “hsc2hs” with deduplicated
> flags.  It will help that the other deduplication code was written by
> the same person who filed the bug you linked to earlier.  Once the patch
> lands, we can apply it to our Cabal and then Stack will build.  Yay!

Sorry I'm a bit confused by all this. I guess if we can rely on a
patch into cabal that would be the least effort, right?
Is there already a patch to deduplicate flags passed to hsc2hs?  Do we
need to comment anywhere or express support?

- John