Flakes break when being part of an sha256 git repository

[zilti]

I have a sha256-based git repository with a flake.nix in it. I cannot properly use my flake:

$ use flake . --impure --show-trace

warning: Git tree '/home/zilti/projects/chicken6-flake' is dirty
warning: creating lock file '/home/zilti/projects/chicken6-flake/flake.lock'
error:
       … while updating the lock file of flake 'git+file:///home/zilti/projects/chicken6-flake'

       … while fetching the input 'git+file:///home/zilti/projects/chicken6-flake'

       error: hash '198461b4bc842fde74f065402dcf42e3956eb36e8a990d2782e7b4bd861bc67a' has wrong length for hash type 'sha1'
direnv: nix-direnv: Evaluating current devShell failed. Falling back to previous environment!
direnv: export +NIX_DIRENV_DID_FALLBACK ~PATH

[zilti]

Same goes for when one's trying to use a flake as a template using nix flake new -t: This will result in fatal: mismatched algorithms: client sha1; server sha256.

[Mic92]

Where can we case the chicken6-flake?

[zilti]

Here: https://gitea.lyrion.ch/zilti/chicken6-flake/

[telometto]

Bumping this as I am experiencing the same issue. Unfortunately, though, I cannot share it because it is a secrets repo.

---

Error

nix flake update
fatal: mismatched algorithms: client sha1; server sha256
warning: could not update mtime for file '/home/zeno/.cache/nix/gitv3/0kj22dq3as8lbiyzf0f13niymkr9i90l4r8l7xrh8hc91223bi6n-shallow/refs/heads/main': changing modification time of '"/home/zeno/.cache/nix/gitv3/0kj22dq3as8lbiyzf0f13niymkr9i90l4r8l7xrh8hc91223bi6n-shallow/refs/heads/main"' (using `utimensat`): No such file or directory
error:
       … while updating the lock file of flake 'path:/home/zeno/.versioncontrol/github/projects/personal/nix-config?lastModified=1733175920&narHash=sha256-CuB/Z1PxMlawg%2Be8jOJK8mtjJa7neAxzICtNwTsJOQE%3D'

       … while updating the flake input 'mySecrets'

       … while fetching the input 'git+ssh://git@gitlab.com/<MY/REPO>.git?ref=main&shallow=1'

       error: resolving Git reference 'main': revspec 'main' not found

Flake excerpt

  inputs = {
    ...
    mySecrets = {
      url = "git+ssh://git@gitlab.com/<MY/REPO>.git?ref=main&shallow=1";
      flake = false;
    };
    ...

[miallo]

Flakes seem to have issues in general with sha256...

git init --object-format=sha256 test
cd test
nix flake init
nix build .#hello

Will throw

error:
… while fetching the input 'git+file:///home/user/test'
error: opening Git repository '"/home/user/test"': unknown object format 'sha256'

[roberth]

libgit2 has some support for sha256, but it is experimental

option(EXPERIMENTAL_SHA256     "Enable experimental SHA256 support (for R&D/testing)"  OFF)

Would enabling this affect the stability of the sha1 behaviors?

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2024-12-16-nix-team-meeting-minutes-203/57483/1