crane.lib.<system> attribute missing in flake outputs for revision dfd9a8dfd09db9aad544c4d3b6c47b12562544a5` (and latest) in specific Nix environment

[evanlhatch]

Describe the bug**
When using crane as a flake input, I'm encountering an error: attribute 'lib' missing when trying to access inputs.crane.lib.${system} or crane.lib.${system} within my flake.nix. This occurs when crane is pinned to revision dfd9a8dfd09db9aad544c4d3b6c47b12562544a5 (which is what my flake.lock resolves to, even after nix flake lock --update-input crane) or when attempting to use the latest from the default branch.

The flake.nix for crane at revision dfd9a8dfd09db9aad544c4d3b6c47b12562544a5 appears to correctly export lib for each system via flake-utils. However, evaluation in my environment does not yield this structure.

Steps To Reproduce

1. Create a minimal flake.nix (or use the one provided below which attempts to build a Rust project).
2. Ensure flake.lock pins crane to github:ipetkov/crane/dfd9a8dfd09db9aad544c4d3b6c47b12562544a5.
3. Attempt to evaluate or build the flake (e.g., nix build .#somePackage or nix flake check .).
4. The evaluation fails with error: attribute 'lib' missing.

nix repl Test Confirmation:
The issue is confirmed directly in nix repl:

nix-repl> craneFlake = builtins.getFlake "github:ipetkov/crane/dfd9a8dfd09db9aad544c4d3b6c47b12562544a5"
nix-repl> craneFlake.lib
error: attribute 'lib' missing
       at «string»:1:1:
            1| craneFlake.lib
             | ^

nix-repl> craneFlake.lib.x86_64-linux
error: attribute 'lib' missing
       at «string»:1:1:
            1| craneFlake.lib.x86_64-linux
             | ^

This demonstrates that the flake object for this revision, as fetched and evaluated by builtins.getFlake, does not have the expected lib attribute structure.

Expected behavior
inputs.crane.lib.${system} (or crane.lib.${system} when crane is the system-specific output) should provide the crane library for the given system, allowing access to functions like overrideToolchain, buildPackage, etc.

Screenshots or Error Logs**
(Error from nix build .#ng using the flake below)

error: attribute 'lib' missing
       at /path/to/my/project/ng/flake.nix:21:31: 
           20|
           21|           craneLibForSystem = crane.lib.${system}; # This is the access point we expect to work
             |                               ^
           22|           craneLib = craneLibForSystem.overrideToolchain rustToolchain;

My flake.nix (simplified, focusing on the crane access):

{
  description = "Minimal Flake to demonstrate crane.lib issue";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    rust-overlay.url = "github:oxalica/rust-overlay";
    crane.url = "github:ipetkov/crane"; # Lock file pins this to dfd9a8d...
  };

  outputs = { self, nixpkgs, rust-overlay, crane, ... }@inputs:
    let
      supportedSystems = [ "x86_64-linux" ]; 
      mkSystemOutputs = system:
        let
          overlays = [ (import rust-overlay) ];
          pkgs = import nixpkgs { inherit system overlays; };
          rustToolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
          
          craneLibForSystem = crane.lib.${system}; 
          craneLib = craneLibForSystem.overrideToolchain rustToolchain;

          dummyPackage = craneLib.buildPackage {
            pname = "dummy";
            version = "0.1.0";
            src = craneLib.path ./.; 
            cargoExtraArgs = "--bin dummy_bin"; 
          };
        in {
          packages = {
            default = dummyPackage;
          };
        };
      perSystemOutputs = nixpkgs.lib.genAttrs supportedSystems mkSystemOutputs;
    in {
      packages = nixpkgs.lib.mapAttrs (sn: so: so.packages) perSystemOutputs;
    };
}

(To make the above flake runnable for reproduction, a minimal rust-toolchain.toml, a dummy Cargo.toml, and src/main.rs with fn main() {} would be needed.)

My flake.lock entry for crane:

{
  "nodes": {
    "crane": {
      "locked": {
        "lastModified": 1746291859, 
        "narHash": "sha256-DdWJLA+D5tcmrRSg5Y7tp/qWaD05ATI4Z7h22gd1h7Q=",
        "owner": "ipetkov",
        "repo": "crane",
        "rev": "dfd9a8dfd09db9aad544c4d3b6c47b12562544a5",
        "type": "github"
      },
      "original": {
        "owner": "ipetkov",
        "repo": "crane",
        "type": "github"
      }
    }
    // ... other inputs from my project's flake.lock ...
  },
  "root": "root",
  "version": 7
}

Environment

• Nix version: Nix 2.28.3 (Please note this is an unusual version string)
• OS: NixOS 25.05.20250508.dda3dcd (nixos-unstable)

Additional context

• Running nix flake update or nix flake lock --update-input crane does not change the pinned revision of crane (dfd9a8d...).
• The crane flake's own flake.nix at revision dfd9a8d... appears to correctly structure its outputs to include lib per system.

Could there be an issue with how this specific revision dfd9a8d... of crane evaluates or exposes its outputs, or a compatibility problem with my Nix environment (perhaps related to the Nix version)?

Thank you for your help!

[ipetkov]

Hi @evanlhatch thanks for the report and the detailed reproduction!

The lib output was deprecated in #617 and subsequently removed in #692, so you'll need to change your configuration to use the mkLib output now. If you don't need to customize the nixpkgs instantiation you can use craneLib = inputs.crane.mkLib nixpkgs.legacyPackages.${system}; (or if you do need to customize the nixpkgs instantiation use craneLib = inputs.crane.mkLib pkgs;).

Take a look at the most recent version of any of the examples to get started. Hope this helps!

[evanlhatch]

Thanks!