`happy` is not properly auto built in a fresh install about hadrian

[adamse]

Adding support for --with-(alex|happy): https://phabricator.haskell.org/D5307

[alpmestan]

I think you're using too old a Cabal version, because since 2.2 IIRC things that are in build-tool-depends are also installed automatically. Any chance this could be the problem?

[hvr]

cabal does build them; the problem is a different one: how to make them visible to ./configure so it can persist/record their locations in the config-settings.

Here's two ways which should work to query for the locations for the build-tools that were requested by hadrian.cabal:

$ cabal new-exec --project=$PWD/hadrian/cabal.project sh -- -c 'command -v alex'
/home/hvr/.cabal/store/ghc-8.4.4/alex-3.2.4-4006f020d0bf93fca9fc50e9f961c4a2af3341f7a44d2bfa6f7feb9c7d6e930b/bin/alex

or alternatively

$ cabal new-exec --project=$PWD/hadrian/cabal.project which -- alex
/home/hvr/.cabal/store/ghc-8.4.4/alex-3.2.4-4006f020d0bf93fca9fc50e9f961c4a2af3341f7a44d2bfa6f7feb9c7d6e930b/bin/alex

One thing I I've been missing from configure is support for --with-alex= and --with-happy=; in the past I temporarily modified PATH during the ./configure invocation until the locations were persisted; but that's not a precise method.

[alpmestan]

(@TerrorJack told me on IRC this problem is now solved.)

[TerrorJack]

@alpmestan ghc-8.4.4 has Cabal-2.2.0.1 in global pkgdb, and I'm using cabal-install-2.4.0.0 compiled using Cabal-2.4.0.1, so Cabal version should be relatively new here.

[alpmestan]

Hmm, I'm confused then. Maybe @hvr will know?

[snowleopard]

I am not sure we should consider this issue resolved.

As @hvr points out, the general solution is unclear. Others may he hit by the same problem.

[adamse]

We landed proper support for passing alex & happy to configure in https://gitlab.haskell.org/ghc/ghc/merge_requests/61

I’m happy to take a stab at fixing this ticket if we still want it?

[snowleopard]

@adamse Yes, it would be great, thank you!

Perhaps, you could open a GHC Trac ticket (or should it be a GitLab issue now?) to briefly describe the problem and proposed solution, so that it is more visible to GHC developers?

[adamse]

@snowleopard see https://ghc.haskell.org/trac/ghc/ticket/16120#ticket

[snowleopard]

@adamse Awesome, thank you! I'm therefore closing this issue.