Enable tests for ghc 9 and promote ghcVersion check

[jneira]

• Promote GhcVersion datatype and ghcVersion function to ghcide to make it available to all the codebase
• Use them to replace CPP for code which paths compile for several ghc versions
• Add GHC90 version and remove GHC84 (as we dont support it anymore)
• Include test execution for ghc-9.0 and windows and macos (we could remove macos after a succesful execution, as we are not testing it for any version)

[pepeiborra]

This is very nice, thank you @jneira !!
To prevent the MIN_VERSION macros from coming back, I would also remove the CPP extension pragmas and remove the modules from the allowlist in the ghcide hlint file.

[jneira]

This is very nice, thank you @jneira !!
To prevent the MIN_VERSION macros from coming back, I would also remove the CPP extension pragmas and remove the modules from the allowlist in the ghcide hlint file.

Hmm, afaics the unique module where i could remove CPP language pragma was ghcide/session-loader/Development/IDE/Session.hs and it was not listed in the modules where CPP is allowed:

haskell-language-server/ghcide/.hlint.yaml

Lines 88 to 110 in ce15ff6

	# Shady extensions
	- name: CPP
	within:
	- Development.IDE.Compat
	- Development.IDE.Core.FileStore
	- Development.IDE.Core.Compile
	- Development.IDE.Core.Rules
	- Development.IDE.Core.Tracing
	- Development.IDE.GHC.Compat
	- Development.IDE.GHC.ExactPrint
	- Development.IDE.GHC.Orphans
	- Development.IDE.GHC.Util
	- Development.IDE.Import.FindImports
	- Development.IDE.LSP.Outline
	- Development.IDE.Spans.Calculate
	- Development.IDE.Spans.Documentation
	- Development.IDE.Spans.Common
	- Development.IDE.Spans.AtPoint
	- Development.IDE.Plugin.CodeAction
	- Development.IDE.Plugin.Completions
	- Development.IDE.Plugin.Completions.Logic
	- Development.IDE.Types.Location
	- Main

But hlint should warn about that, so surely i am missing something

[jneira]

I've marked circleci job and the ubuntu test job for 9.0.1 as required
EDIT: Also the build for macos and ghc 8.10.5

[jneira]

We have a succesful run with tests included for ghc-9.0.1 and macos: https://github.com/haskell/haskell-language-server/pull/2001/checks?check_run_id=2997169971
So i am gonna disable tests for it too 😢

[pepeiborra]

I guess we still need CPP around imports and other non-expression sections

[jneira]

The test job for windows and ghc-9.0.1 is getting stuck in the last builds 😟