Nix-build, a user .gitignore and haskell issue

1

I had an issue where having *.cabal in .gitignore[1] made nix-build -A plutus-playground.server (from plutus-apps fail due to there being “No cabal file found”. Regardless of whether having *.cabal in .gitignore is a good idea, I wonder how did the issue come about – is the nix-build process adding files and commiting to repositories while building, or is it filtering inputs based on user’s .gitignore file?

[1] because of using package.yaml everywhere. This is perhaps a practice that has swung back to including .cabal files too given that stack recommends it and cabal has gotten better.

2

Ignored files are not included in the build process. In 99.999% of cases it makes no sense.

In the case of the Plutus stuff, generally lib.cleanGit or something is used. In the case of flakes, Nix natively does this.

2 Likes
3

Right, but depending on the contents of my .gitignore is a little bit of a lottery, no? Users might add things there that they want to generally ignore, but that doesn’t necessarily match what the package authors ignored.

4

Can you please share exactly what you are trying and how?

Your users gitgnore should never be considered by any fetchers.

5

I essentially ran nix-build -A plutus-playground.server from within plutus-apps repo at commit 41149926c108c71831cfe8d244c83b0ee4bf5c8a.

Had had the issue for a while and hadn’t find any solutions, but today decided to start from a clean linux user – and there it did work! so started to iterate with comment things out from my configuration.nix and running nixos-rebuild until I found the line in .gitignore.

System: nixos-version is “22.05pre345234.b2737d4980a (Quokka)”, nix-build --version is “nix-build (Nix) 2.5.1”.

6

Are you referring to a global ignore file (core.excludesfile) or .git/info/exclude? Or just a regular .gitignore file in the repo?

7

Yes, it’s the one pointed to from my ~/.gitconfig’s core.excludesfile setting.