`cabal haddock` rebuilds (all?) the dependencies since cabal-install-3.9.0.0 (or 3.8?)

[phadej]

E.g. trying with tree-diff

% ~/.ghcup/bin/cabal-3.9.0.0 build   
Up to date

but then

% ~/.ghcup/bin/cabal-3.9.0.0 haddock
Build profile: -w ghc-8.6.5 -O1
In order, the following will be built (use -v for more details):
 - StateVar-1.2.2 (lib) (requires build)
 - attoparsec-0.14.4 (lib:attoparsec-internal) (requires build)
 - base-compat-0.12.2 (lib) (requires build)
 - base-orphans-0.8.7 (lib) (requires build)
 - bytestring-builder-0.10.8.2.0 (lib) (requires build)
 - colour-2.3.5 (lib) (requires build)
 - data-array-byte-0.1.0.1 (lib) (requires build)
 - dlist-1.0 (lib) (requires build)
 - generically-0.1 (lib) (requires build)
 - indexed-traversable-0.1.2 (lib) (requires build)
 - integer-logarithms-1.0.3.1 (lib) (requires build)
 - primitive-0.7.4.0 (lib) (requires build)
 - splitmix-0.1.0.4 (lib) (requires build)
 - tagged-0.8.6.1 (lib) (requires build)
 - th-abstraction-0.4.5.0 (lib) (requires build)
 - transformers-compat-0.7.2 (lib) (requires build)
 - vector-stream-0.1.0.0 (lib) (requires build)
 - contravariant-1.5.5 (lib) (requires build)
 - ansi-terminal-0.11.4 (lib) (requires build)
 - hashable-1.4.2.0 (lib) (requires build)
 - random-1.2.1.1 (lib) (requires build)
 - distributive-0.6.2.1 (lib) (requires build)
 - vector-0.13.0.0 (lib) (requires build)
 - ansi-wl-pprint-0.6.9 (lib) (requires build)
 - unordered-containers-0.2.19.1 (lib) (requires build)
 - time-compat-1.9.6.1 (lib) (requires build)
 - text-short-0.1.5 (lib) (requires build)
 - scientific-0.3.7.0 (lib) (requires build)
 - data-fix-0.3.2 (lib) (requires build)
 - OneTuple-0.3.1 (lib) (requires build)
 - uuid-types-1.0.5 (lib) (requires build)
 - QuickCheck-2.14.2 (lib) (requires build)
 - comonad-5.0.8 (lib) (requires build)
 - charset-0.3.9 (lib) (requires build)
 - attoparsec-0.14.4 (lib) (requires build)
 - indexed-traversable-instances-0.1.1.1 (lib) (requires build)
 - base-compat-batteries-0.12.2 (lib) (requires build)
 - bifunctors-5.5.14 (lib) (requires build)
 - parsers-0.12.11 (lib) (requires build)
 - witherable-0.4.2 (lib) (requires build)
 - semigroupoids-5.3.7 (lib) (requires build)
 - assoc-1.0.2 (lib) (requires build)
 - these-1.1.1.1 (lib) (requires build)
 - strict-0.4.0.1 (lib) (requires build)
 - semialign-1.2.0.1 (lib) (requires build)
 - aeson-2.1.1.0 (lib) (requires build)
 - tree-diff-0.2.2 (lib) (configuration changed)
Starting     base-orphans-0.8.7 (lib)
Starting     bytestring-builder-0.10.8.2.0 (lib)
Starting     data-array-byte-0.1.0.1 (lib)
Starting     colour-2.3.5 (lib)
...

This is bad regression. (I didn't use 3.8.1.0 as it was broken otherwise, so cannot tell if it's already broken too).

[phadej]

Oh, it tries to build haddocks for all the dependencies too? And then occasionally fails when they are not buildable. :O

like (with GHC-8.4.4 - older GHCs have buggier haddocks):

Error: cabal-3.9.0.0: Failed to build documentation for vector-0.13.0.0 (which is required by test:cabal-parsers-golden from cabal-install-parsers-0.5, bench:cabal-parsers-bench from cabal-install-parsers-0.5 and others).

[phadej]

So I guess this is intentional https://github.com/haskell/cabal/blob/master/changelog.d/issue-7462, but how to not do this, changelog doesn't tell.

[Mikolaj]

Guessing: "--disable-documentation"? Perhaps the PR has some discussion.

[Mikolaj]

But agreed, this needs to be spelled out.

[phadej]

#7462 (comment) says that --disable-documentation doesn't work. Let's see what CI setup reports if I add --disable-documentation.

[Mikolaj]

#8330 supposedly fixes it.

[phadej]

Ok, seems that issue is lacking documentation (in the changelog). The --disable-documentation reverts the behavior to previous (which is what I want in CI).

I'm not a fan of #7462 change, as you can control that by having documentation: True in ~/.cabal/config (or at least you should ). As building dependencies always with documentation would save you building them twice.

I wouldn't changed the default for cabal haddock, but I guess that ship has sailed.

I'm sad there is no way to control the cabal haddock default behavior, I expect to mostly use --disable-documentation, as I use cabal haddock to check that formatting is correct, and appreciate fast (initial) feedback. (I lookup docs on Hackage, not that much locally, tbh).

[Mikolaj]

Thank you for the investigation. I've noted down to improve this bit of release notes (mention --disable-documentation) at release time.

[ulysses4ever]

Can someone explain me why #7462 is mentioned here while the OP does not mention cabal haddock but rather cabal build. #7462 is supposed to only affect cabal haddock. Does it affect cabal build somehow?

[Mikolaj]

@ulysses4ever: the second code snippet has cabal haddock.

[ulysses4ever]

@Mikolaj oh, my bad, thank you! I think I will change the title of the issue so that it mentions haddock too.