fix handling of cargo.lock outside a workspace

if Cargo.toml is outside a workspace, Cargo.lock is generated in the
same directory as Cargo.toml

nix_update/update.py

@@ -308,7 +308,17 @@ def disable_copystat():
             cwd=tempdir,
         )
 
-        shutil.copy(tempdir + "/Cargo.lock", Path(filename).parent / "Cargo.lock")
+        if (
+            lockfile_in_subdir := Path(tempdir)
+            / opts.lockfile_metadata_path
+            / "Cargo.lock"
+        ).exists():
+            # if Cargo.toml is outside a workspace, Cargo.lock is generated in the same directory as Cargo.toml
+            lockfile = lockfile_in_subdir
+        else:
+            lockfile = Path(tempdir) / "Cargo.lock"
+
+        shutil.copy(lockfile, Path(filename).parent / "Cargo.lock")
 
 
 def update_composer_deps_hash(opts: Options, filename: str, current_hash: str) -> None:

tests/test_cargo_lock_generate.py

@@ -85,3 +85,50 @@ def test_with_lockfile_metadata_path(helpers: conftest.Helpers) -> None:
         assert (
             "https://github.com/lancedb/lancedb/compare/python-v0.11.0...0.12.0" in diff
         )
+
+
+def test_with_lockfile_metadata_path_outside_workspace(
+    helpers: conftest.Helpers,
+) -> None:
+    """A test for a project where the target Cargo.toml is outside a workspace.
+
+    In this case, Cargo.lock is generated in the subdirectory where Cargo.toml is located, not in the project root.
+    For example, https://github.com/lancedb/lance/blob/v0.16.1/Cargo.toml
+    """
+    with helpers.testpkgs(init_git=True) as path:
+        main(
+            [
+                "--file",
+                str(path),
+                "--commit",
+                "cargoLock.generate.with-lockfile-metadata-path-outside-workspace",
+                "--version",
+                "v0.16.1",
+                "--generate-lockfile",
+                "--lockfile-metadata-path",
+                "python",
+            ]
+        )
+        subprocess.run(
+            [
+                "nix",
+                "eval",
+                "--raw",
+                "--extra-experimental-features",
+                "nix-command",
+                "-f",
+                path,
+                "cargoLock.generate.with-lockfile-metadata-path-outside-workspace.cargoDeps",
+            ],
+            check=True,
+            text=True,
+            stdout=subprocess.PIPE,
+        ).stdout.strip()
+        diff = subprocess.run(
+            ["git", "-C", path, "show"],
+            text=True,
+            stdout=subprocess.PIPE,
+            check=True,
+        ).stdout.strip()
+        print(diff)
+        assert "https://github.com/lancedb/lance/compare/v0.15.0...v0.16.1" in diff

tests/testpkgs/cargo-lock-generate/with-lockfile-metadata-path-outside-workspace/default.nix

@@ -0,0 +1,23 @@
+{ python3Packages
+, rustPlatform
+, fetchFromGitHub
+}:
+
+python3Packages.buildPythonPackage rec {
+  pname = "pylance";
+  version = "0.15.0";
+
+  src = fetchFromGitHub {
+    owner = "lancedb";
+    repo = "lance";
+    rev = "v${version}";
+    hash = "sha256-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=";
+  };
+
+  nativeBuildInputs = [
+    rustPlatform.cargoSetupHook
+    rustPlatform.maturinBuildHook
+  ];
+
+  cargoDeps = rustPlatform.importCargoLock { lockFile = ./Cargo.lock; };
+}

tests/testpkgs/default.nix

@@ -5,6 +5,7 @@
   cargoLock.expand = pkgs.callPackage ./cargo-lock-expand { };
   cargoLock.generate.simple = pkgs.callPackage ./cargo-lock-generate/simple { };
   cargoLock.generate.with-lockfile-metadata-path = pkgs.callPackage ./cargo-lock-generate/with-lockfile-metadata-path { };
+  cargoLock.generate.with-lockfile-metadata-path-outside-workspace = pkgs.callPackage ./cargo-lock-generate/with-lockfile-metadata-path-outside-workspace { };
   cargoLock.update = pkgs.callPackage ./cargo-lock-update { };
   composer = pkgs.callPackage ./composer.nix { };
   crate = pkgs.callPackage ./crate.nix { };