cabal new-haddock does not work for autogenerated gi-* bindings

[garetxe]

Hello,

I am having some trouble trying to generate docs for the gi-* set of libraries I maintain (autogenerated bindings for gtk and friends) using cabal new-haddock.

The bindings all use build-type: Custom, and generate the list of modules to be compiled when configuring the package using a confHook (see here), using a custom Setup.hs script. The list of modules to be compiled depends on the system compiling the library, and cannot be known in advance, hence the weird build system.

Despite the somewhat involved Setup.hs logic, both cabal new-build and cabal old-haddock have been working well in practice so far.

But cabal new-haddock seems to do nothing:

$ git clone https://github.com/haskell-gi/haskell-gi.git
$ cd haskell-gi
$ cabal new-haddock --haddock-for-hackage gi-glib
Build profile: -w ghc-8.6.1 -O1
In order, the following will be built (use -v for more details):
 - gi-glib-2.0.18 (file /home/inaki/cvs/haskell-gi/dist-newstyle/build/x86_64-linux/ghc-8.6.1/haskell-gi-0.21.5/cache/build changed)

Any advice? I would like to switch to the new workflow, but this issue has been stopping me from doing so.

[garetxe]

To elaborate a bit: the logic in the current Setup.hs way of doing things is fairly straightforward:

• We leave the exposed-modules stanza in the .cabal file out.
• We introduce a confHook that
  • Generates the bindings (if they are not already there), and returns the list of modules that have been generated.
  • Fills in the exposedModules of the library, see this line.

I would be happy to clarify further, and any suggestions on how to do this in a better way would be welcome too.

[harpocrates]

This smells like a bug, but I can get the repro to work. Both new-build and new-haddock fail with the same error message.

haskell-gi$ cabal --version
cabal-install version 2.4.1.0
compiled using version 2.4.1.0 of the Cabal library

haskell-gi$ cabal new-build gi-glib -w ghc-8.6.1 -O1

When using configuration(s) from /Users/atheriault/Documents/code/haskell-gi/cabal.project, the following errors occurred:
The package location 'bindings/GLib/gi-glib.cabal' does not exist.
The package location 'bindings/GObject/gi-gobject.cabal' does not exist.
The package location 'bindings/Atk/gi-atk.cabal' does not exist.
The package location 'bindings/Gio/gi-gio.cabal' does not exist.
The package location 'bindings/cairo/gi-cairo.cabal' does not exist.
The package location 'bindings/Pango/gi-pango.cabal' does not exist.
The package location 'bindings/PangoCairo/gi-pangocairo.cabal' does not exist.
The package location 'bindings/GdkPixbuf/gi-gdkpixbuf.cabal' does not exist.
The package location 'bindings/Gdk/gi

[garetxe]

Sorry! I forgot a step. Please try the following instead:

$ git clone https://github.com/haskell-gi/haskell-gi.git
$ cd haskell-gi
$ pushd bindings; cabal new-run genBuildInfo $(./PKGS.sh); popd
$ cabal new-haddock --haddock-for-hackage gi-glib

[harpocrates]

There are now also some cabal errors...

$ pushd bindings; cabal new-run --allow-newer genBuildInfo $(./PKGS.sh); popd
~/Code/Scratch/haskell-gi/bindings ~/Code/Scratch/haskell-gi ~/Code/Scratch
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] next goal: haskell-gi (user goal)
[__0] rejecting: haskell-gi-0.21.5 (conflict: pkg-config package
gobject-introspection-1.0>=1.32, not found in the pkg-config database)
[__0] rejecting: haskell-gi-0.21.4, haskell-gi-0.21.3, haskell-gi-0.21.2,
haskell-gi-0.21.1, haskell-gi-0.21.0, haskell-gi-0.20.3, haskell-gi-0.20.2,
haskell-gi-0.20.1, haskell-gi-0.20, haskell-gi-0.18, haskell-gi-0.17.4,
haskell-gi-0.17.3, haskell-gi-0.17.2, haskell-gi-0.17.1, haskell-gi-0.17,
haskell-gi-0.15, haskell-gi-0.14, haskell-gi-0.13, haskell-gi-0.12,
haskell-gi-0.11, haskell-gi-0.10.2, haskell-gi-0.10.1, haskell-gi-0.10,
haskell-gi-0.9, haskell-gi-0.8 (constraint from user target requires ==0.21.5)
[__0] fail (backjumping, conflict set: haskell-gi)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: haskell-gi

~/Code/Scratch/haskell-gi ~/Code/Scratch

Perhaps there's a specific commit I could try that you know works?

[garetxe]

You need to install some devel packages (since these packages are bindings to C libraries). For Fedora you can do:

sudo dnf install gobject-introspection-devel webkitgtk4-devel gtksourceview3-devel

and for Debian/Ubuntu

sudo apt-get install libgirepository1.0-dev libwebkit2gtk-4.0-dev libgtksourceview-3.0-dev

(More options are listed in here.)

Thanks for taking the time to look into this, and sorry for the complications!

[harpocrates]

Alright. I never managed to replicate this on haskell-gi, but I was able to make a simple package that reproduced this bug. The issue is in

cabal/cabal-install/Distribution/Client/ProjectBuilding.hs

Line 1172 in 6a97912

hasHaddocks = not (null (elabPkgDescription ^. componentModules name))

Looks like elabPkgDescription does not factor in changes from the conf hook. The behaviour of skipping Haddock for targets lacking exposed modules was introduced in 338c358.

[harpocrates]

I don't see how an ElaboratedConfiguredPackage could ever include information from the confHook though... Should we perhaps move this check elsewhere?