we have this in cargo.nix:

    //
      lib.optionalAttrs (stdenv.buildPlatform.rust.rustcTarget != stdenv.hostPlatform.rust.rustcTarget)
        {
          HOST_PKG_CONFIG_PATH = "${pkgsBuildBuild.pkg-config}/bin/pkg-config";
        }

Looks like rustfmt is broken on x86_64-darwin on nixos-25.05:

https://buildbot.nix-community.org/#/builders/2847/builds/5266/steps/1/logs/stdio (from Nixvim CI)

With staging-next done, we can do https://github.com/NixOS/nixpkgs/pull/421558 now

This is just the removal of the usages, not the removal of the logic.

For the logic, should we make setting useFetchCargoVendor a warning/error in 25.11?
We could just remove the logic completely, but then people might not remove it from their out-of-tree derivations...

With staging-next done, we can do https://github.com/NixOS/nixpkgs/pull/421558 now

This is just the removal of the usages, not the removal of the logic.

For the logic, should we make setting useFetchCargoVendor a warning/error in 25.11?
We could just remove the logic completely, but then people might not remove it from their out-of-tree derivations...
Or, since we didn't have too long of a period where useFetchCargoVendor was forced to be set to true manually, we should just remove it without warnings.