GHC version support

[avdv]

• define a clear GHC version support range (keep this economical w.r.t. test coverage).

  See GHC release status page: https://gitlab.haskell.org/ghc/ghc/-/wikis/GHC-Status

• evaluate test coverage and expand where needed

  • e.g. GHC bindist patches undergo start-script tests.
  • but changes to rules are not checked on the full GHC version range

• keep up-to-date

  • GHC upgrade(s)
  • what do we do on the blockers for ARM cross-compilation support?
  • can we use tooling (dependabot/renovate) to stay up-to-date going forward?

    
    ### Tasks

• [ ] https://github.com/tweag/rules_haskell/issues/1933

• [ ] https://github.com/tweag/rules_haskell/issues/1986

• [ ] https://github.com/tweag/rules_haskell/issues/1987

• [ ] https://github.com/tweag/rules_haskell/issues/2031

• [ ] https://github.com/tweag/rules_haskell/issues/2081

• [ ] https://github.com/tweag/rules_haskell/issues/2082

• [ ] https://github.com/tweag/rules_haskell/issues/2093

[avdv]

Ideally, we should strive to support (and test) the recent stable GHC releases:

Current Stable Releases

• 9.8.1
• 9.6.3
• 9.4.8
• 9.2.8

Also, we should take into account the supported GHC versions from stackage:

• 9.2.8 -> LTS 20.26
• 9.4.8 -> LTS 21.24
• 9.6.3 -> nightly
• 9.8.1 -> nightly

Note: apparently, GHC 9.2.x has been demoted from stable to an "old" release, as it is no longer listed under "Current Stable Releases" on the download page.

[aherrmann]

@avdv is this one done now or is there still work remaining here?

[avdv]

is this one done now or is there still work remaining here?

We want to also support GHC 9.8 and eventually remove GHC 9.2 from testing since it is not a stable release anymore (but that can wait until we decide it's the right time)

[aherrmann]

@avdv Thanks for clarifying, sounds good!