Cabal 3.8 does not appear to track extra-source-file rebuilds correctly

[michaelpj]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce

It's large, but here's the reproducer: https://github.com/input-output-hk/plutus

cabal build plutus-core:plutus-core
# edit plutus-core/cost-model/data/builtinCostModel.json
cabal v2-build plutus-core:plutus-core
# observe no recompliation

Expected behavior

Since there is a file that depends on plutus-core/cost-model/data/builtinCostModel.json using addDependentFile, I would expect modifying it to trigger a rebuild.

System information

• NixOS
• cabal 3.8.1
• ghc 9.2.4

Additional context

We've confirmed that this works on cabal 3.6.2, and not on 3.8.1. I've tried a few semi-random things to try and get cabal to notice the change:

• Move the file to the package root to avoid directory separators in the pattern.
• Remove all the other extra-source-files
• Explicitly add a call to addDependentFile <path> to the relevant module.
• Changing to use a wildcard match on the file extension
• Bumping the cabal-version of the cabal file
• Add the package directory to the extra-source-file path in case there was a CWD mixup and it was looking from the project root somehow.

None of these have worked.

[gbaz]

First I want to clear up a confusion. As far as I know, addDependentFile never was tracked by cabal. What did happen was there was a patch (#6889) to add extra source files to cabal's rebuild tracking. I would very much like to figure out why that seems to no longer work.

[EDIT -- for now I think I found the flag to twiddle to stop requiring the nix shell]

[gbaz]

Additionally, can it be that this tracking works in a single cabal package, but it is the introduction of multiple packages in a joint cabal-project that breaks it?

[michaelpj]

Sorry not to have a smaller reproducer, I didn't have time to make one and I thought this was better than nothing :(

I could have tested your hypotheses out for you but it looks like you found it already, which is excellent, thank you!