ghcide fails when including servant-server as dep. with cannot statisfy ...

[rsoeldner]

When including servant-server as a dependeny, ghcide will print the following error:

ghcide version: 0.0.6 (GHC: 8.6.5) (PATH: /home/rsoeldner/.cabal/store/ghc-8.6.5/ghcide-0.0.6-4aa57fa4249b5929e468d2f1efb68a574c18cca14176427ab91eb114ea8962a2/bin/ghcide)
Ghcide setup tester in /home/rsoeldner/work/example.
Report bugs at https://github.com/digital-asset/ghcide/issues

Step 1/6: Finding files to test in /home/rsoeldner/work/example
Found 2 files

Step 2/6: Looking for hie.yaml files that control setup
Found 1 cradle

Step 3/6, Cradle 1/1: Implicit cradle for /home/rsoeldner/work/example
Cradle {cradleRootDir = "/home/rsoeldner/work/example", cradleOptsProg = CradleAction: default}

Step 4/6, Cradle 1/1: Loading GHC Session
Loaded package environment from /home/rsoeldner/work/example/.ghc.environment.x86_64-linux-8.6.5
ghcide: <command line>: cannot satisfy -package-id servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3: 
    servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3 is unusable due to missing dependencies:
      wai-app-static-3.1.7.1-fecbcfd54e54b19aae9409125afc0169209de51d3fc050d8e9632dc6af452750
    (use -v for more information)

I'm using the following workflow (running NixOs):

1. entering nix-shell
2. installing ghcide (cabal v2-install ghcide)
3. create new project (cabal init) and added servant and servant-server as dep
4. running cabal v2-configure --write-ghc-environment-files always for creating .ghc.env file
5. run ghcide

I have uploaded this minimal, running version to Github https://github.com/rsoeldner/ghcide-example-issue

Maybe I do somethign fundamentally wrong ?

[ndmitchell]

CC @mpickering as this sounds like hie-bios issue.

Does cabal v2-repl work for you? Can you try creating an explicit hie.yaml?

[rsoeldner]

@ndmitchell cabal v2-repl works without any issues.

Adding the following hie.yaml does not change the reported behavior:

cradle: {cabal: {component: "exe:example"}}

Running ghcide produces the following output:

ghcide version: 0.0.6 (GHC: 8.6.5) (PATH: /home/rsoeldner/.cabal/store/ghc-8.6.5/ghcide-0.0.6-4aa57fa4249b5929e468d2f1efb68a574c18cca14176427ab91eb114ea8962a2/bin/ghcide)
Ghcide setup tester in /home/rsoeldner/work/example.
Report bugs at https://github.com/digital-asset/ghcide/issues

Step 1/6: Finding files to test in /home/rsoeldner/work/example
Found 2 files

Step 2/6: Looking for hie.yaml files that control setup
Found 1 cradle

Step 3/6, Cradle 1/1: Loading ./hie.yaml

Step 4/6, Cradle 1/1: Loading GHC Session
ghcide: <command line>: cannot satisfy -package-id servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3: 
    servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3 is unusable due to missing dependencies:
      wai-app-static-3.1.7.1-fecbcfd54e54b19aae9409125afc0169209de51d3fc050d8e9632dc6af452750
    (use -v for more information)

[mpickering]

Is there a way to get ghcide to show the flags it's trying to use to start a session?

[rsoeldner]

@mpickering as far as I know, no. maybe @ndmitchell or @cocreature can help here ?

[rsoeldner]

Hi @mpickering ,

I just modified the the cradleToSession function inside exe/Main.hs to:

cradleToSession :: Cradle -> IO HscEnvEq
cradleToSession cradle = do
    cradleRes <- getCompilerOptions "" cradle
    opts <- case cradleRes of
        CradleSuccess r -> pure r
        CradleFail err -> throwIO err
        -- TODO Rather than failing here, we should ignore any files that use this cradle.
        -- That will require some more changes.
        CradleNone -> fail "'none' cradle is not yet supported"
    libdir <- getLibdir
    putStrLn $ "## Libdir: " ++ libdir
    putStrLn $ "## OPTS:" ++ (show opts)
    env <- runGhc (Just libdir) $ do
        _targets <- initSession opts
        getSession
    initDynLinker env
    newHscEnvEq env

to print our the libdir and opts parameter, see below of the output:

ghcide version: 0.0.6 (GHC: 8.6.5) (PATH: /home/rsoeldner/work/ghcide-0.0.6/dist-newstyle/build/x86_64-linux/ghc-8.6.5/ghcide-0.0.6/x/ghcide/build/ghcide/ghcide)
Ghcide setup tester in /home/rsoeldner/work/ghcide-0.0.6.
Report bugs at https://github.com/digital-asset/ghcide/issues

Step 1/6: Finding files to test in /home/rsoeldner/work/ghcide-0.0.6
Found 2 files

Step 2/6: Looking for hie.yaml files that control setup
Found 1 cradle

Step 3/6, Cradle 1/1: Loading /home/rsoeldner/work/example/hie.yaml

Step 4/6, Cradle 1/1: Loading GHC Session
Cradle {cradleRootDir = "/home/rsoeldner/work/example", cradleOptsProg = CradleAction: cabal}
## Libdir: /nix/store/npw9cl22d89yach0lk18m93jiipx42rz-ghc-8.6.5/lib/ghc-8.6.5

## OPTS:ComponentOptions {componentOptions = ["-fbuilding-cabal-package","-O0","-outputdir","/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/example-tmp","-odir","/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/example-tmp","-hidir","/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/example-tmp","-stubdir","/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/example-tmp","-i","-i/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/example-tmp","-i/home/rsoeldner/work/example/.","-i/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/autogen","-i/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/global-autogen","-I/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/autogen","-I/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/global-autogen","-I/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/example-tmp","-optP-include","-optP/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/build/example/autogen/cabal_macros.h","-hide-all-packages","-Wmissing-home-modules","-no-user-package-db","-package-db","/home/rsoeldner/.cabal/store/ghc-8.6.5/package.db","-package-db","/home/rsoeldner/work/example/dist-newstyle/packagedb/ghc-8.6.5","-package-db","/home/rsoeldner/work/example/dist-newstyle/build/x86_64-linux/ghc-8.6.5/example-0.1.0.0/x/example/package.conf.inplace","-package-id","base-4.12.0.0","-package-id","servant-0.16.2-ec01031ffd8f923d66f9d2f492dddcb2951f8eceee29c58dffc326f82eab3dcd","-package-id","servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3","-XHaskell2010","./Main.hs","-hide-all-packages"], componentDependencies = ["example.cabal","cabal.project"]}


ghcide: <command line>: cannot satisfy -package-id servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3: 
    servant-server-0.16.2-60a275bf83d1527b502d21b0db5b200a68977694dd0fe8bab84edc3a5e354fb3 is unusable due to missing dependencies:
      wai-app-static-3.1.7.1-fecbcfd54e54b19aae9409125afc0169209de51d3fc050d8e9632dc6af452750
    (use -v for more information)

[mpickering]

And what is in /nix/store/npw9cl22d89yach0lk18m93jiipx42rz-ghc-8.6.5/lib/ghc-8.6.5?

My guess is that not servant-server because ghcide is setting the wrong libdir.

[rsoeldner]

correct, the path contains basic haskell libs (mtl, stm, time, text,) but nothing related to servant nor servant-server.

Shouldn't the libdir be set to the path where cabal v2-build fetched the dependencies?

[ndmitchell]

Currently we use the libdir from the ghc-paths library, unless you are in Nix, in which case we use the Nix variable - see https://github.com/digital-asset/ghcide/blob/master/exe/Main.hs#L58. You are in Nix but not using the Nix ghc which confuses our heuristic. My guess is we should have hie-bios tell us the right libdir itself, and hie-bios should do that by calling ghc --print-libdir to ask for it and putting it in the Cradle. That accounts for the fact that Nix changes the libdir by altering the ghc on the $PATH, which means our environment variable trick can die (which is what goes wrong here).

[fendor]

We solved the problem in hie by selecting the used ghc version based on the cradle type and then calling ghc --print-libdir and stack ghc -- --print-libdir respectively. I agree that it makes sense to add this to a cradle definition in hie-bios.
Responsible code:
https://github.com/haskell/haskell-ide-engine/blob/master/hie-plugin-api/Haskell/Ide/Engine/Cradle.hs#L91

Usage:
https://github.com/haskell/haskell-ide-engine/blob/master/hie-plugin-api/Haskell/Ide/Engine/Cradle.hs#L147

We encountered some problems with calling cabal exec -- ghc --print-libdir because this only works after the project has been at least configured.
I think we can upstream a lot of this code into the cradle definition.

[rsoeldner]

@ndmitchell thank you for investigating this. Setting the env inside my nix-shell with export NIX_GHC_LIBDIR=$(ghc --print-libdir) fixed most issues. One missing is related to https://github.com/haskell/haskell-ide-engine/issues/1093 which I can ignore.

[domenkozar]

Duplicates https://github.com/hercules-ci/ghcide-nix/issues/26

[jneira]

I think there were some changes to make nix work after this issue: @rsoeldner could you check if it is resolved with lastest ghcide version?

[rsoeldner]

@jneira havent encountered this issue again, thanks!