`--hoogle` flag of `haddock-project` makes no difference

[ozkutuk]

Describe the bug
I am not exactly sure what the expected outcome of cabal haddock-project --hoogle is, but from what I can tell, the --hoogle flag makes no difference at all.

To Reproduce
Steps to reproduce the behavior:

$ cabal haddock-project --output=docs
$ cabal haddock-project --output=docs-hoogle --hoogle
$ meld docs docs-hoogle  # or any other diff tool that can diff directories

Expected behavior
--hoogle flag should have an effect

System information

• Operating system: NixOS
• cabal: 3.12.1.0
• ghc: 9.6.5

[ulysses4ever]

Cc @coot

[coot]

I don't use hoogle myself, so it would be nice to get a contribution from sb who knows what to expect 😉.

[ulysses4ever]

Oh, so that's another instance of a flag not implemented but silently swallowed. Unfortunately, it's a common issue that we have in Cabal code base after the introduction of v2 interface.

PRs welcome for implementing cabal haddock-project --hoogle.

[ozkutuk]

I was thinking maybe cabal haddock-project --hoogle could generate a single hoogle database for all the packages involved rather than individual databases for each package (like cabal haddock --haddock-hoogle does). However, this doesn't seem necessary; pointing hoogle to the top-level documentation directory works just fine, AFAICT it collects all the hoogle databases from each individual package:

$ hoogle generate --database=db.hoo --local=docs/
# the generated database has all the packages, can be observed by running a server:
$ hoogle server --local --database=db.hoo

Maybe the best thing to do is to remove the --hoogle flag from haddock-project altogether? (or maybe @kokobd has some ideas to integrate some stuff from cabal-hoogle under this flag?)

[ulysses4ever]

Maybe the best thing to do is to remove the --hoogle flag from haddock-project

My previous message was trying to suggest that it’s easier said than done.

[coot]

I was thinking maybe cabal haddock-project --hoogle could generate a single hoogle database for all the packages involved rather than individual databases for each package (like cabal haddock --haddock-hoogle does).

Yes, that's the right way to do it for haddock-project.