using ghc-mod with stack: cabal-helper-wrapper: ghc: readCreateProcess: runInteractiveProcess: exec: does not exist (No such file or directory)

[deflexor]

Just did fresh install of stack, then haskell via stack setup, then configured emacs as described here: https://github.com/serras/emacs-haskell-tutorial/blob/master/tutorial.md

Then after starting emacs and opening .hs file got this error message:

cabal-helper-wrapper: ghc: readCreateProcess: runInteractiveProcess: exec: does not exist (No such file or directory)
ghc-mod: GMEProcess "readProcessStderrChan" "/home/deflexor/.stack/global/.stack-work/install/x86_64-linux/lts-3.9/7.10.2/libexec/cabal-helper-wrapper" ["/tmp/hhi","/tmp/hhi/.stack-work/dist/x86_64-linux/Cabal-1.22.4.0"] (Left 1)
cabal-helper-wrapper: ghc: readCreateProcess: runInteractiveProcess: exec: does not exist (No such file or directory)
ghc-mod: GMEProcess "readProcessStderrChan" "/home/deflexor/.stack/global/.stack-work/install/x86_64-linux/lts-3.9/7.10.2/libexec/cabal-helper-wrapper" ["/tmp/hhi","/tmp/hhi/.stack-work/dist/x86_64-linux/Cabal-1.22.4.0"] (Left 1)

There is no dist subdirectory in project dir. GHC, version 7.10.2

[DanielG]

Okay so it's complaining the ghc executable does not exist.

My guess is you installed ghc-mod using stack, you're using Stack's --install-ghc builtin GHC thing. Therefore the GHC that Stack installed is not on your PATH and you're trying to use ghc-mod in a project that is not a Stack project.

Easy fix: just add any version of ghc to your PATH. It's only needed to build cabal-helper's runtime wrapper thing so anything that is old enough to be compatible with whatever version of Cabal is in your projects will do. (this most likely means 7.8 or 7.10 or so since you're using Stack)

[DanielG]

Maybe we ought to check if ghc exists on the path and ask stack for one (if it's installed) when we can't find it. Should be relatively easy to add if anyone wants to shoot me a PR.

[DanielG]

(Note to self: remember to remove wiki entry when this is resolved: https://github.com/kazu-yamamoto/ghc-mod/wiki#cabal-helper-wrapper-ghc--does-not-exist)

[nrolland]

if that's an easy fix, it would probably be a good opportunity to make it an introduction to ghc-mod structure to see how you would investigate about this. that would give other contributors a map of where things are

[codygman]

Is anyone working on this? It looks like a nice weekend (maybe less) project.

[DanielG]

Actually I just tested this and it works even if you don't have a system wide ghc installed.

https://github.com/kazu-yamamoto/ghc-mod/blob/master/Language/Haskell/GhcMod/CabalHelper.hs#L123

patchStackPrograms looks on Stack's bin-path and uses the path to it's GHC instead.

@codygman are you getting the same error as well? It might be something I fixed in git so do try the version from master if so.

[DanielG]

I think this is fixed in master just reopen if I'm wrong.

[x-ji]

Still not working for me. I instlaled ghc-mod with stack, resolver version lts-4.0. Do I have to manually install ghc-mod via master branch instead of using stack then? However when I tried to run stack init/stack install in the downloaded repo, it says some of the dependencies can't be met.

[DanielG]

Ah that's interesting, I can reproduce this but only when .stack-work doesn't exists yet. So after the first run it works just fine.

[codygman]

That's interesting.
On Jan 10, 2016 11:18 AM, "Daniel Gröber" notifications@github.com wrote:

Ah that's interesting, I can reproduce this but only when .stack-work
doesn't exists yet.

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Reply to this email directly or view it on GitHub
#660 (comment).

[DanielG]

Ah I found the cause writeAutogenFiles from cabal-helper doesn't allow passing down Programs so I forgot doing it there. I think I can make a minor upgrade that should be able to go into stackage.

[DanielG]

Gah now I have to maintain a stable branch for stackage too. Anyways give it a go:

$ git clone https://github.com/DanielG/ghc-mod -b stable-5.4 ghc-mod-stable-5.4
$ cd ghc-mod-stable-5.4
$ stack install

[DanielG]

So this is going into 5.5 not sure if we're going to do a minor release for 5.4 too.

[codygman]

👍 thanks for your hard work!

On Sun, Jan 17, 2016 at 1:16 PM, Daniel Gröber notifications@github.com
wrote:

Closed #660 #660.

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#660 (comment).