unbreak cabal haddock --disable-documentation

[ulysses4ever]

Trying to fix my fault from #8259 (thanks @andreasabel for noticing): cabal haddock --disable-documentation seems to work as expected with this patch.

Below is a description of a problem I initially had but no more. Preserved for historical interest.

---

But the testsuite is not cooperating. I see two options: you, guys, help me or allow me to ditch the test.

Here's the deal with the test:

main = cabalTest . withRepo "repo" . fails $
    cabal "haddock" ["--disable-documentation", "B"]

should work, but it fails even when

❯ cabal run cabal-tests -- --with-cabal=(cabal list-bin cabal) cabal-testsuite/PackageTests/NewHaddock/DisableDoc/cabal.test.hs --accept

I see the output I'm expecting to see, in particular:

 100% (  2 /  2) in 'B'
Warning: B: could not find link destinations for:

        - A.a

but the output ends with

cabal-tests: callProcess: /nix/store/glag1h91br1sqk489rzzp6mvmxf0pmiy-ghc-9.0.2/bin/runghc-9.0.2 "--" "--ghc-arg=-i" "--ghc-arg=-no-user-package-db" "--ghc-arg=-package-db" "--ghc-arg=/home/artem/.cabal/store/ghc-9.0.2/package.db" "--ghc-arg=-package-db" "--ghc-arg=/home/artem/tmp/cabal/enable-doc-regress/cabal/dist-newstyle/packagedb/ghc-9.0.2" "--ghc-arg=-package-id" "--ghc-arg=Cabal-3.9.0.0-inplace" "--ghc-arg=-package-id" "--ghc-arg=Cabal-syntax-3.9.0.0-inplace" "--ghc-arg=-package-id" "--ghc-arg=async-2.2.4-2b04cd6dcc0fc474e0072aec3462b9c67410113d7befe87d8f668b6a29dfe996" "--ghc-arg=-package-id" "--ghc-arg=base-4.15.1.0" "--ghc-arg=-package-id" "--ghc-arg=cabal-testsuite-3-inplace" "--ghc-arg=-package-id" "--ghc-arg=clock-0.8.3-12cb68ccaf6e6206378be8082c1ee7435ae9bbce4022f1012bd6cd3e5c8fc2aa" "--ghc-arg=-package-id" "--ghc-arg=exceptions-0.10.4" "--ghc-arg=-package-id" "--ghc-arg=filepath-1.4.2.1" "--ghc-arg=-package-id" "--ghc-arg=optparse-applicative-0.16.1.0-72520bdb9dc24ef310719d7357cf6ce0dac24c8b958b2d2663b3d141a87f2fd6" "--ghc-arg=-package-id" "--ghc-arg=process-1.6.14.0-42e0058a6e7535eea211d226cecb5365b21bf90abcca43d0f0527ff0319ccdca" "--ghc-arg=-package-id" "--ghc-arg=transformers-0.5.6.2" "cabal-testsuite/PackageTests/NewHaddock/DisableDoc/cabal.test.hs" "--builddir" "/home/artem/tmp/cabal/enable-doc-regress/cabal/dist-newstyle/build/x86_64-linux/ghc-9.0.2/cabal-testsuite-3" "cabal-testsuite/PackageTests/NewHaddock/DisableDoc/cabal.test.hs" "--with-cabal" "/home/artem/tmp/cabal/enable-doc-regress/cabal/dist-newstyle/build/x86_64-linux/ghc-9.0.2/cabal-install-3.9.0.0/x/cabal/build/cabal/cabal" "--accept" (exit 1): failed

Which is no good, as far as I understand. If I remove fails in the .hs file, the failure in the end seems to be the same. So, I'm probably using fails wrong?..

---

Please include the following checklist in your PR:

• [x] Patches conform to the coding conventions.
• [x] Any changes that could be relevant to users have been recorded in the changelog.
• [x] The documentation has been updated, if necessary.

Please also shortly describe how you tested your change. Bonus points for added tests!

[ulysses4ever]

More or less, what I see locally reproduces in the CI: https://github.com/haskell/cabal/runs/7571243588?check_suite_focus=true

[Mikolaj]

Is Warning: B: could not find link destinations for a hard error that exits with 1, or is it just a warning after which you continue?

[ulysses4ever]

@Mikolaj wow, I was positive that removing fails didn't change the output and was still saying "fail" but now it's not. SO, removing fails works and if I --accept output and remove the patch, then the test fails, so it's good. Waiting for CI.

[ulysses4ever]

@Mikolaj does it need a changelog entry?

[Mikolaj]

@Mikolaj does it need a changelog entry?

I don't think so. You are fixing a change that wasn't yet released, so nobody's going to know. :)

[ulysses4ever]

Right, I forgot #8259 wasn't backported to 3.8.