Allow disabling freeze files in cabal.project.local

[merijn]

I would like to commit a cabal.project.freeze file to my repository so that non-Haskell savvy users can easily/reliably build my Haskell code, but since I also use the repository to actively develop this would make it tricky/annoying to add new packages/change bounds, etc. while programming.

If there was a way to override/skip freeze files in cabal.project.local I could simply commit the freeze file in the repo and, in my development clone, modify the cabal.project.local that I have anyway to ignore the freeze file while developing.

[23Skidoo]

In the past, @dcoutts suggested adding an explicit include mechanism for config files: for example, cabal.project could explicitly include ~/.cabal/config and cabal.project.local, and cabal.project.local could by default include cabal.project.freeze.

Then it'd be easy to implement something like configure --ignore-freeze-file as well as extra project-local config files (see #6016 (comment)).

[hvr]

@23Skidoo How would that design allow me to ignore the existence of a .freeze or .local file (while honoring the existence of a cabal.project file) only via CLI (i.e. w/o renaming or deleting any files)

[23Skidoo]

For the .freeze file: configure --ignore-freeze-file would regenerate the .local file without the include cabal.project.freeze line. For the .local file: you'd need to edit the cabal.project file and remove the include cabal.project.local line.

We'd also need to start versioning the cabal.project file because everyone's currently relying on implicit include semantics.