Installing GHC is slow. Possibly use cache?

[UlyssesZh]

Installing GHC is slow. Is it possible to utilize caches if the versions of ghcup and cabal to be installed are exactly the one already installed before?

[unhammer]

I'd like to do this too. I saw commercialhaskell/stack#5754 (comment) claim to be able to cache ghcup ghc's, but when I tried something like that on windows-latest with

  - name: Cache GHC installation
    uses: actions/cache@1bd1e32a3bdc45362d1e726936510720a7c30a57 # v4.2.0
    id: ghcup
    with:
      path: |
        C:\tools\${{ env.GHC_VERSION }}
        C:\ghcup\bin\*
        C:\ghcup\cache\*
        C:\ghcup\config.yaml
        C:\ghcup\ghc\${{ env.GHC_VERSION }}
      key: ghcup--${{ env.GHC_VERSION }}

I see

  Attempting to access tool ghc at location C:/ghcup/bin
  Succeeded accessing tool ghc at location C:/ghcup/bin
  C:\ghcup\bin\ghcup.exe set ghc 9.2.8
  [ Warn  ] New GHCup version available: 0.1.40.0. To upgrade, run 'ghcup upgrade'
  [ Info  ] verifying digest of: gs.exe
  [ Error ] [�
  C:\ghcup\bin\ghcup.exe unset ghc
  [ Info  ] verifying digest of: gs.exe
  [ Info  ] GHC successfully unset
  Attempting to install ghc 9.2.8 using chocolatey
  ::stop-commands::***
  C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe choco install ghc --version 9.2.8 --allow-multiple-versions --ignore-dependencies --no-progress --limit-output
  Installing the following packages:
  ghc
  By installing, you accept licenses for the packages.
  Downloading package from source 'https://community.chocolatey.org/api/v2/'

as if it's there, but not verified, or something like that?