Not working with cabal-2.4.1.0

[newhoggy]

Looks like the setup-config is located in a slightly different location when building with cabal-2.4.1.0:

$  /Users/jky/wrk/haskell-works/haskell-ide-engine-6/.stack-work/install/x86_64-osx/lts-12.14/8.4.3/bin/cabal-helper-wrapper "--with-ghc=ghc" "--with-ghc-pkg=ghc-pkg" "--with-cabal=cabal" "v1-style" "/Users/jky/wrk/haskell-works/hw-json" "/Users/jky/wrk/haskell-works/hw-json/dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1" "package-db-stack" "flags" "compiler-version" "ghc-merged-pkg-options" "config-flags" "non-default-config-flags" "ghc-src-options" "ghc-pkg-options" "ghc-lang-options" "ghc-options" "source-dirs" "entrypoints" "needs-build-output"
cabal-helper-wrapper: /Users/jky/wrk/haskell-works/hw-json/dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1/setup-config: openFile: does not exist (No such file or directory)
$ find dist-newstyle -name setup-config
dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1/t/hw-json-test/opt/setup-config
dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1/opt/setup-config

[newhoggy]

Notice that haskell-ide-engine expects the file to be located here:

dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1/setup-config

but it is actually found here:

dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1/opt/setup-config

It is unclear if it is the cabal version that is causing this difference or if it is the cabal file version, which I've specified like this:

$ head -n 1 hw-json.cabal
cabal-version:  2.2

[newhoggy]

After downgrading my cabal file to remove cabal-version: 2.2 and add cabal-version: >= 1.10, the problem still persists.

[newhoggy]

Work around:

$ cd dist-newstyle/build/x86_64-osx/ghc-8.4.3/hw-json-0.9.0.1/
$ ln -s opt/setup-config setup-config

[newhoggy]

Work around in the general case:

# haskell-ide-engine work-around
for x in $(find dist-newstyle -name setup-config | grep '/opt/setup-config$' | sed 's|/opt/setup-config$||g'); do
  ( cd $x
    ln -fs opt/setup-config setup-config
  )
done

[alanz]

@newhoggy this is a problem with new-build in general, and the interim support we have at the moment, which basically only supports the library component.

[AlexeyRaga]

Reading setup-config seems to be unreliable anyway because producing it requires new-build to be executed first. Even new-configure doesn't seem to be enough.

One of the implications is that changing the version number in a .cabal file changes the path to the file which doesn't exist until new-build is issued so the IDE reports readCreateProcess errors.
Which is not an ideal user experience.

Can it be worked around without requiring setup-config to be there?

[AlexeyRaga]

I am curious, should we be using v2-style instead in the cabal helper?
Since dist-newstyle/cache/plan.json is in an "easier" location and it is generated by cabal new-configure we could use it, and issue cabal new-configure automatically when it is not present?

I wanted to try, but I see that to v2-style I should provide something that is called Unit, which is, perhaps, looks something like <my-executable-name>-<version>-inplace and this is where I am a bit lost. Which one do I suppose to use? How do I determine the "right" executable name, assuming that there can be >1 of them in the cabal file?

Can anyone provide a direction here?

[alanz]

@AlexeyRaga , the proper new-build support is coming via https://github.com/alanz/haskell-ide-engine/tree/bleeding-edge-c-h

It sort of works at the moment, but has issues with caching, and detecting changes in the project being developed.

[AlexeyRaga]

@alanz awesome, thanks! :) Can't wait! :)

[tjarvstrand]

Any news? I'm eagerly awaiting this! :)

[alanz]

@DanielG has managed to find some time to work on this solidly in the next few months, so rather than doing my band-aid patch, we will wait for his work.

And we are hoping for some assistance from @power-fungus and @fendor too.