cabal v2-update behaves strangely even with index-state set

[Fuuzetsu]

Describe the bug
I have a cabal.project.freeze file present with index-state value. If I run cabal v2-update, sometimes it uses the right index-state value the first time. If I re-run cabal v2-update without any changes, it will fetch latest Hackage. Re-running cabal v2-update fetches the latest hackage.

If I then specify the index-state value manually to cabal v2-update, on first run it will still show that it's using most recent Hackage snapshot. When I re-run the command, it finally uses the index-state.

To Reproduce
Steps to reproduce the behavior:

$ grep index-state cabal.project.freeze 
index-state: hackage.haskell.org 2021-01-04T03:29:50Z

$ cabal v2-update
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-04T03:29:50Z

$ cabal v2-update
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-14T01:36:23Z

$ cabal v2-update
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-14T01:36:23Z

Here I give up and use the value explicitly.

$ cabal v2-update hackage.haskell.org,2021-01-04T03:29:50Z
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-14T01:36:23Z

$ cabal v2-update hackage.haskell.org,2021-01-04T03:29:50Z
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-04T03:29:50Z

$ cabal v2-update hackage.haskell.org,2021-01-04T03:29:50Z
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-04T03:29:50Z

So now I'm at the index state I actually wanted. If I now run cabal v2-update without arguments, on first run it keeps the original index and on subsequent runs in starts using latest Hackage.

$ cabal v2-update
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-04T03:29:50Z

$ cabal v2-update
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-14T01:36:23Z

$ cabal v2-update
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-01-14T01:36:23Z

Expected behavior
If I use cabal v2-update in a directory with cabal.project.freeze with index-state set, I expect it to use the value.

Alternatively it should always fetch the latest hackage.

What I do not expect to happen is that running cabal v2-update twice with exactly the same arguments (or none) jumps between two different indices.

System information

$ uname -a
Linux aya 5.4.83 #1-NixOS SMP Fri Dec 11 12:23:33 UTC 2020 x86_64 GNU/Linux

$ ghc --numeric-version
8.8.3

$ cabal --numeric-version
3.4.0.0

To be more precise, I'm using 3.4.0.0-rc4.

[Fuuzetsu]

I checked the ~/.cabal/packages/hackage.haskell.org/01-index.timestamp file.

After running cabal v2-update it always says HEAD.

After running cabal v2-update hackage.haskell.org,2021-01-04T03:29:50Z it always says 2021-01-04T03:29:50Z.

So the behaviour seems consistent, just the messages seems completely wrong: probably it's showing the index state that we were using, not the one we are using currently.

[andreabedini]

The following exchange between me and cabal just happened. I don't have a index-state set in cabal.project so the conditions seem a bit simpler. I am actually not in a cabal project at all.

[~] cabal update
Downloading the latest package list from hackage.haskell.org
Updated package list of hackage.haskell.org to the index-state 2021-03-25T13:49:23Z
To revert to previous state run:
    cabal v2-update 'hackage.haskell.org,2021-03-20T04:12:58Z'

[~] cabal v2-update 'hackage.haskell.org,2021-03-20T04:12:58Z'
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-03-25T13:49:23Z

[~] cat ~/.cabal/packages/hackage.haskell.org/01-index.timestamp
2021-03-20T04:12:58Z

[~] cabal v2-update 'hackage.haskell.org,2021-03-20T04:12:58Z'
Downloading the latest package list from hackage.haskell.org
Package list of hackage.haskell.org is up to date at index-state 2021-03-20T04:12:58Z

Yeah, the message seems completely wrong.

[andreabedini]

This should have been fixed by #7934. Feel free to re-open if the issue persist.