Fix index-state syntax in cabal.project

[andreabedini]

The index-state stanza in cabal.project is "last wins", so

index-state: 2022-12-24T00:00:00Z
index-state: cardano-haskell-packages 2022-11-02T15:34:17Z

would set the index state of hackage to HEAD.

The correct syntax to set the index-state of both repositories is

index-state:
  , hackage.haskell.org 2022-12-24T00:00:00Z
  , cardano-haskell-packages 2022-11-02T15:34:17Z

haskell.nix has trouble parsing the index-state syntax with multiple repositories, so we repeat the index-state for Hackage. Cabal will ignore the first index-state stanza anyway.

Description

Add your description here, if it fixes a particular issue please provide a
link
to the issue.

Checklist

• Commit sequence broadly makes sense
• Commits have useful messages
• New tests are added if needed and existing tests are updated
• Any changes are noted in the changelog
• Code is formatted with fourmolu (which can be run with scripts/fourmolize.sh
• Self-reviewed the diff

[lehins]

Cabal will ignore the first index-state stanza anyway.

Are you sure about this? I definitely did not observe this behavior: "would set the index state of hackage to HEAD."

I can say for sure because this repo would have problems building for a month if hackage was at HEAD. It was deliberately set to:

index-state: 2022-12-24T00:00:00Z

because starting with 26th of December our tooling was broken due to incorrect bounds on Hackage starting with this index:

index-state: 2022-12-26T00:00:00Z

It was only recently fixed, but my point still stands, if hackage was set to HEAD I would expect it to be broken.
Could you also please link to some issues on cabal or haskell.nix repos, so we know exactly why we have to do this duplicate work, and more importantly when we can stop doing.

[andreabedini]

Are you sure about this? I definitely did not observe this behavior: "would set the index state of hackage to HEAD."

100% sure, the cabal issue reference is haskell/cabal#8568. Also the prompt to fix the all the repos I can find is because it broke cardano-node today (link).

Note that if you use nix, you are always safe because haskell.nix can parse the index-state: 2022-12-24T00:00:00Z line and give you an appropriate hackage tarball. So what cabal thinks is irrelevant in that case.