Show why configuring dependencies failed

[9999years]

When act-as-setup configure fails, it doesn't indicate which dependencies are missing entirely and which ones don't satisfy the version constraints. The errors from cabal build are more informative, but aren't available in all contexts (nixpkgs Haskell builds, for example, use the act-as-setup interface). This makes it immediately clear what sort of dependency error has occurred.

Before (cabal-install 3.12.1.0):

Configuring test-pkg-0.1.0.0...
Error: [Cabal-8010]
Encountered missing or private dependencies:
    base <=4.18,
    foobar,
    test-pkg:{bar-internal, foo-internal}

After:

Configuring test-pkg-0.1.0.0...
Error: [Cabal-8010]
Encountered missing or private dependencies:
    base <=4.18 (installed: 4.19.1.0),
    foobar (missing),
    test-pkg:{bar-internal,foo-internal} (missing: :bar-internal)

Please let me know if you're interested in this patch and I can write tests and polish up the documentation.

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[geekosaur]

Unfortunately, I'm not qualified to determine whether this is logically correct, only that it looks reasonable (and being a spell checker 😛).

[9999years]

Ah, the tests are failing because they pass the exact ID of the base library (which varies per GHC version under test), and that shows up in the output. Not sure how to work around that with the expect tests.

[jasagredo]

You should probably work out how to identify those and replace them with a common string in OutputNormalizer.hs

[9999years]

@jasagredo Fixed the tests and added a new one to demonstrate the error messages I showed off in the PR description, PTAL!

[jasagredo]

I think this looks good in general 👍. I am not very knowledgeable in dependency resolution, so I cannot tell if there are other places that would need changes, but the changes that were done here look correct. Basically propagating some more information.

I added some comments, in particular I would merge those 3 new modules into Dependency.hs, but that I guess is personal preference.

[jasagredo]

Aaaarg so sorry @9999years I accidentally pressed Update branch while scrolling. Let me try to re-push your previous version.

[jasagredo]

Restored 👍

[fgaz]

This is missing a changelog entry

[9999years]

@fgaz Added a changelog entry, PTAL.

CI failure doesn't look like it's related:

curl: (28) Failed to connect to codeberg.org port 443 after 134854 ms: Connection timed out

Changelog entry added

[geekosaur]

This is an API change, so can't be backported to 3.12. Additionally, 3.10 is now frozen (largely because major merge conflicts will happen thanks to fourmolu) so no backports can be done to it.