Figure out ghc project version even if ghc is not installed

[hasufell]

Invoking haskell-language-server-wrapper --project-ghc-version may fail with:

$ haskell-language-server-wrapper --project-ghc-version                                                                           326ms  Fri 17:36
Found "/home/hasufell/git/ghcup-hs/hie.yaml" for "/home/hasufell/git/ghcup-hs/a"
Failed to get project GHC version: CradleError {cradleErrorDependencies = [], cradleErrorExitCode = ExitFailure 1, cradleErrorStderr = ["Error when calling cabal exec -v0 -- ghc --print-libdir","","cabal: Cannot find the program 'ghc'. User-specified path 'ghc-8.10.1' does\nnot refer to an executable and the program is not on the system path.\n\n"]}

when the ghc in question is not installed. That means the extension is currently unable to set up a project GHC, unless it is already installed somewhere.

This is cabal specific, but rather unergonomic.

[klauso]

I get exactly that error and it prevents me from using the VSCode Haskell extension.

Is there a workaround until this issue is properly fixed? What is the "ghc in question"? I seem to have the GHC version for my project installed already.

[hasufell]

@klauso

Please provide more info:

1. which platform are you using?
2. are you using ghcup? If so, what's the output of ghcup list?
3. do you have any other GHCs globally installed?
4. what is the output of haskell-language-server-wrapper --numeric-version and haskell-language-server-wrapper --project-ghc-version (run it in your project)
5. what's the project cradle hie.yaml? Are you using cabal or stack?
6. what is your VSCode haskell extension configuration?

[klauso]

1. Apple M1 on macOS 12.3.1
2. Yes, I'm using ghcup.

ghcup list yields:

   Tool  Version  Tags                      Notes     
✗  ghc   7.10.3   base-4.8.2.0              no-bindist
✗  ghc   8.0.2    base-4.9.1.0              no-bindist
✗  ghc   8.2.2    base-4.10.1.0             no-bindist
✗  ghc   8.4.1    base-4.11.0.0             no-bindist
✗  ghc   8.4.2    base-4.11.1.0             no-bindist
✗  ghc   8.4.3    base-4.11.1.0             no-bindist
✗  ghc   8.4.4    base-4.11.1.0             no-bindist
✗  ghc   8.6.1    base-4.12.0.0             no-bindist
✗  ghc   8.6.2    base-4.12.0.0             no-bindist
✗  ghc   8.6.3    base-4.12.0.0             no-bindist
✗  ghc   8.6.4    base-4.12.0.0             no-bindist
✗  ghc   8.6.5    base-4.12.0.0             no-bindist
✗  ghc   8.8.1    base-4.13.0.0             no-bindist
✗  ghc   8.8.2    base-4.13.0.0             no-bindist
✗  ghc   8.8.3    base-4.13.0.0             no-bindist
✗  ghc   8.8.4    base-4.13.0.0             no-bindist
✗  ghc   8.10.1   base-4.14.0.0             no-bindist
✗  ghc   8.10.2   base-4.14.1.0             no-bindist
✗  ghc   8.10.3   base-4.14.1.0             no-bindist
✗  ghc   8.10.4   base-4.14.1.0             no-bindist
✗  ghc   8.10.5   base-4.14.2.0                       
✗  ghc   8.10.6   base-4.14.3.0                       
✓  ghc   8.10.7   recommended,base-4.14.3.0           
✗  ghc   9.0.1    base-4.15.0.0             no-bindist
✗  ghc   9.0.2    base-4.15.1.0                       
✗  ghc   9.2.1    base-4.16.0.0                       
✔✔ ghc   9.2.2    latest,base-4.16.1.0                
✗  cabal 2.4.1.0                            no-bindist
✗  cabal 3.0.0.0                            no-bindist
✗  cabal 3.2.0.0                            no-bindist
✗  cabal 3.4.0.0                                      
✗  cabal 3.4.1.0                                      
✗  cabal 3.6.0.0                                      
✔✔ cabal 3.6.2.0  latest,recommended                  
✗  hls   1.1.0                              no-bindist
✗  hls   1.2.0                              no-bindist
✗  hls   1.3.0                              no-bindist
✗  hls   1.4.0                                        
✗  hls   1.5.0                                        
✗  hls   1.5.1                                        
✗  hls   1.6.0.0                                      
✗  hls   1.6.1.0                                      
✓  hls   1.7.0.0  latest,recommended                  
✗  stack 2.5.1                              no-bindist
✗  stack 2.7.1                              no-bindist
✗  stack 2.7.3                                        
✔✔ stack 2.7.5    latest,recommended                  
✔✔ ghcup 0.1.17.7 latest,recommended      

4. I have no haskell-language-server-wrapper executable/link but only a haskell-language-server-wrapper-1.7.0.0 executable (could that be part of the reason?). It reports 1.7.0.0 for --numeric-version . For --project-ghc-version I get

Found "/Users/klaus/git/dualsub/hie.yaml" for "/Users/klaus/git/dualsub/a"
Failed to get project GHC version: CradleError {cradleErrorDependencies = [], cradleErrorExitCode = ExitFailure 1, cradleErrorStderr = ["Error when calling stack setup --silent","",""]}

5. The hie.yaml looks like this:

cradle:
  stack:

I'm using Stack.

6. Do you mean the settings.json ? It looks like this:

{
    "security.workspace.trust.untrustedFiles": "open",
    "coqtop.binPath": "/Users/klaus/.opam/default/bin/ ",
    "haskell.trace.client": "debug",
    "editor.minimap.enabled": false,
    "window.zoomLevel": 1,
    "files.watcherExclude": {
        "**/.bloop": true,
        "**/.metals": true,
        "**/.ammonite": true
    },
    "haskell.manageHLS": "GHCup",
    "haskell.trace.server": "messages",
    "haskell.toolchain": {
    
    }
}

I didn't change anything in the configuration options except enabling debug messages (to investigate this error).

[hasufell]

What happens when you call stack setup in your project?

[klauso]

stack will use a sandboxed GHC it installed
For more information on paths, see 'stack path' and 'stack exec env'
To use this GHC and packages outside of a project, consider using:
stack ghc, stack ghci, stack runghc, or stack exec

[klauso]

I just managed to resolve the issue by

stack config set system-ghc --global true

[hasufell]

I suspect this issue is somehow due to stack's GHC installation on M1. Afaik, stack should provide native M1 GHC binaries, but there may be some unknown caveats. GHCup has full M1 support.

The question is: can you build your project with stack via command line and with system-ghc: false?

[klauso]

Yes, I can, but miraculously the haskell-language-server-wrapper --project-ghc-version stuff works again, too, despite me (to the best of my knowledge) not changing anything else. It's a flaky bug. Sorry for not being particularly helpful in narrowing down the cause.