Nix 2.21 fails to build flakes when using --store

[ipetkov]

Describe the bug

I have a regression test for a project of mine which builds a flake using a different store path via --store. It suddenly started failing with the 2.21 release, but works with 2.20 just fine.

Steps To Reproduce

git clone https://github.com/ipetkov/crane.git
cd crane/extra-tests/alt-store

# Succeeds
nix run nixpkgs#legacyPackages.x86_64-linux.nixVersions.nix_2_20 \
  -- build .#default \
  --no-write-lock-file \
  --override-input crane ../.. \
  --store $(pwd)/alt-store

# Clean up
sudo rm -rf ./alt-store

# Fails
nix run nixpkgs#legacyPackages.x86_64-linux.nixVersions.nix_2_21 \
  -- build .#default \
  --no-write-lock-file \
  --override-input crane ../.. \
  --store $(pwd)/alt-store

Expected behavior

The flake should build fine with both Nix 2.20 and 2.21

Priorities

Add 👍 to issues you find important.

[ivan-tkatchev]

Extremely important issue, currently in Nix 2.21 chroot stores do not work at all.
Works correctly for Nix 2.18.2, so the regression was introduced somewhere between these two versions.

[Ericson2314]

Sounds like #9852

[fricklerhandwerk]

Triaged in Nix team meeting:

• Potential fix: Fix flake evaluation in chroot stores #10345
• Related: Regression with ~/.local/share/nix/root used as a chroot store #10331

[edolstra]

I can confirm that this is fixed by #10345.

[nixos-discourse]

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

https://discourse.nixos.org/t/2023-03-27-nix-team-meeting-134/42961/1