Installation fails with GHC < 8

[ivanperez-keera]

I recently had to go to GHC 7.10* to compile a game that uses X11, and installation failed due to the change from -fno-warn-unused-binds to -Wno-unused-binds.

This is probably very low priority, but it would be great if the cabal files of X11-1.10* prevented installation with older GHCs so cabal picked X11-1.9.2, which was the latest version that used a flag compatible with GHC 7.10. Alternatively, you could also do:

  if impl(ghc >= 8)
    ghc-options: -Wno-unused-binds
  else
    ghc-options: -fno-warn-unused-binds

although you may not want to have to keep that around for very old, unsupported versions of GHC, which would be perfectly understandable.

*There was an outstanding bug in the GHC 8.* series that made some games break with GHC 8.*.

[slotThe]

I think this was bumped because we dropped support for these older GHC versions in xmonad and -contrib. If the name of the flag is really the only reason why X11 does not compile in 7.10 right now, I don't see a reason why we shouldn't make that distinction in the cabal file

[ivanperez-keera]

With the change above, X11-1.10.1 compiles with GHC 7.10.3 and the game I mentioned above works.

[liskin]

We can either add the condition or just switch back to only using -fno-warn-* if that's still supported in GHC 9. Would be nice to open a PR that does either and also adds GHC 7.10 to the test matrix. The X11 library is unlikely to see significant changes, so supporting older GHCs shouldn't be a problem.

[ivanperez-keera]

I don't have GHC 9 to try it, but everything in the docs seems to suggest that the syntax is with -W. I see no reference to -fno-warn-* flags anymore.

I can submit a PR including the condition and GHC 7.10 in the matrix.

Does anything need to change in https://github.com/xmonad/X11/blob/master/.github/workflows/haskell-ci.yml#L47-L48? (note: I have zero experience with github actions, which I guess it's what that's for).

[liskin]

I don't have GHC 9 to try it, but everything in the docs seems to suggest that the syntax is with -W. I see no reference to -fno-warn-* flags anymore.

Those references weren't there in 8.10 docs either and I vaguely remember it still worked, so I'd say the easiest way is to just let the CI check it for us. :-)

Does anything need to change in https://github.com/xmonad/X11/blob/master/.github/workflows/haskell-ci.yml#L47-L48? (note: I have zero experience with github actions, which I guess it's what that's for).

This one's generated automatically from tested-with in .cabal by running haskell-ci regenerate. I can regenerate that for you now that I'm back home with proper internet access.

[liskin]

I made a revision on Hackage for both 1.10 and 1.10.1 that bounds base to GHC8+ and I'll now release 1.10.2 that restores compat with GHC7.

[ivanperez-keera]

Awesome! Thanks!

Sorry that I couldn't submit even a simple PR. It's been a crazy time.

[liskin]

FYI: we're dropping GHC 7.10 support at last, but base bound should correctly be bumped now - #105