Cabal postCopy hook doesn't get run

[mgsloan]

stack install nearly works for building ghcjs, but it doesn't use runhaskell Setup.hs copy to install the binaries, and so the ghcjs wrapper scripts don't get installed. See the ghcjs Setup.hs file

[snoyberg]

That's very strange, are you suing that runhaskell Setup.hs install is not calling the postCopy hook?

[mgsloan]

Ahah, that is indeed exactly what's happening: https://mail.haskell.org/pipermail/cabal-devel/2010-July/006535.html

Summary is that runhaskell Setup.hs install doesn't call the postCopy hook, just the postInst hook. So, given that this behavior isn't going to change, I'd say this is a bug with GHCJS's Setup.hs. I'll open a PR fixing that.

[mgsloan]

PR for ghcjs: ghcjs/ghcjs#402

[mgsloan]

Ok, that worked for stack build, but not for stack install, since for install, it copies the binaries here. GHCJS's postCopy / postInstall hook adds more files to the bin directory and uses absolute paths in the wrapper scripts, so in order for it to work correctly, it also needs to be invoked for the final part of

So, it seems like the right thing to do is to invoke runhaskell Setup.hs copy, but this doesn't seem to directly work out. I've tried using Cabal copy with the flags that I'd think would make it work, but I get:

mgsloan@computer:~/user/Downloads/ghcjs-0.1.0$ runhaskell Setup.hs copy --destdir=~/.stack/programs/x86_64-linux/ghcjs-0.1.0_ghc-7.10.2/ --builddir=.stack-work/dist/x86_64-linux/Cabal-1.22.4.0/
Installing library in
~/.stack/programs/x86_64-linux/ghcjs-0.1.0_ghc-7.10.2/home/mgsloan/user/Downloads/ghcjs-0.1.0/.stack-work/install/x86_64-linux/lts-3.4/7.10.2/lib/x86_64-linux-ghc-7.10.2/ghcjs-0.1.0-DQPG8NNmyXW45lzfCqtgbc
Installing executable(s) in
~/.stack/programs/x86_64-linux/ghcjs-0.1.0_ghc-7.10.2/home/mgsloan/user/Downloads/ghcjs-0.1.0/.stack-work/install/x86_64-linux/lts-3.4/7.10.2/bin
Warning: The directory
~/.stack/programs/x86_64-linux/ghcjs-0.1.0_ghc-7.10.2/home/mgsloan/user/Downloads/ghcjs-0.1.0/.stack-work/install/x86_64-linux/lts-3.4/7.10.2/bin
is not in the system search path.

Note the path ~/.stack/programs/x86_64-linux/ghcjs-0.1.0_ghc-7.10.2/home/mgsloan/user/Downloads/ghcjs-0.1.0/.stack-work/install/x86_64-linux/lts-3.4/7.10.2/lib/x86_64-linux-ghc-7.10.2/ghcjs-0.1.0-DQPG8NNmyXW45lzfCqtgbc - looks like what's happening is that the configured install dir is getting appended with the requested destination dir. So, I think we'd need to do another configure in order to use copy for this.

@snoyberg thoughts?

[snoyberg]

I don't get it.

1. Why do you need to use stack install for ghcjs? Keeping it local to the resolver seems correct to me.
2. What's wrong with the original absolute paths being used? Does something actually break?

[mgsloan]

1. Keeping it local to the resolver doesn't work for a few reasons:

   • Which resolver would we look in for our copy of ghcjs? We know to use GHCJS when you specify the ghcjs-0.1.0_ghc-7.10.2 resolver. Which snapshot do we look in for GHCJS?

   • I'm reusing the existing code for maintaining tools in ~/.stack/programs/

   • It's fine to not have it be resolver-local, as long as we

     • Add a stack.yaml file to ghcjs (I found that simply resolver: lts-3.4 was good enough)

     This way, there will always be a canonical set of dependencies for a given ghcjs version.

2. Nothing breaks with the original absolute paths, except that initially they pointed into /tmp/! Infact, my current workaround is to unpack the source tarball into a folder such as .stack/programs/x86_64-linux/ghcjs-0.1.0_ghc-7.10.2/src. Then, I use stack --local-bin-path=... install.

Besides these specific details related to setting up GHCJS, here's the problem:

stack install doesn't invoke Setup.hs when copying binaries to the local-bin-path. It does, however, invoke it when copying them to local-install-root.

[mgsloan]

Looks like this will be resolved by #848