Support transformers-0.6 and mtl-2.3

[phadej]

Looks like that relaxing bounds is enough.

[Mikolaj]

Actually, to have (full) effect, this requires a bump in hackage-security and a release or revision of it: haskell/hackage-security#272

[Mikolaj]

That seems to be the case for cabal-install, but in CI it affects all, because they are built together, so old versions are forced, because cabal-install depends on hackage-security that depends on old transformers and mtl. Oh well.

[phadej]

The CI was capable to build only Cabal and its tests, to allow testing Cabal as soon as there is new stuff (GHC, deps). I hope it's still the case. (allowing flexibility was a reason the templating was done in Haskell, and not YAML).

[Mikolaj]

That makes sense, but I can't find a CI job running with newest GHC and compiling Cabal without cabal-install. @jneira, @andreabedini, is there such a job? The idea is that, unburdened by cabal-install dep constraints, it can catch early incompatibilities with newer versions of packages, GHC-related in particular. Testing packages introduce their own bounds, so perhaps it would make sense to compile without Cabal tests first, and then with tests and run them. Thoughts?

[phadej]

that what e.g. (from 3.2 branch)

cabal/cabal-dev-scripts/src/GenValidate.hs

Line 31 in 48bf107

, GhcJob "7.8.4" False "--lib-only" False ["8.8.3"] libSteps

job did, similar lib-only jobs were used for most recent GHC at the time too.

Implementation wise it was to run a subset of validate.sh steps, so shouldn't be difficult to (re)implement if it gone missing.

[andreabedini]

We can, see #8151

[Mikolaj]

@phadej: thank you for the tip. Now that we actually understand what the "--lib-only" was for and that it wasn't supposed to stick with the same GHC forever, we can improve the new setup. :)

[Bodigrim]

@Mikolaj what are the next steps here? Unless Cabal package allows transformers-0.6, the latter cannot be bundled as a GHC boot library, so almost everyone is tied to transformers-0.5, which is a shame, because transformers-0.6 has been around since July 2021.

At this point we do not really care about cabal-install or hackage-security, they may stick to older infrastructure for a while. But to bump a GHC submodule all boot libraries must be compatible with each other, and I believe Cabal is the last blocker for this to happen.

[Mikolaj]

@Bodigrim: current master branch is fine, right? So it's the matter of including it in GHC? I have no problem with including today's snapshot in GHC, for now, but the final version for GHC 9.6 is tracked at #8571.

[Mikolaj]

Oh, I see, master branch is fine after we merge #8610.

Still. Is that all or may I help further?