How do you handle submodules in dream2nix projects?

[Avi-D-coder]

I'm trying dream2nix on this repo's Rust.
The repo has a submodule cozorocks/rocksdb. What is the right approach using the submodule in d2n builds?
What about when the submodule is in a cargo git dependency?

[DavHau]

I think either the builtin or nixpkgs git fetcher to support fetching submodules.
So how about just fetching the repo including submodules, then throwing it at dream2nix?

[Avi-D-coder]

If I have a Rust crate that depends on another crate as a git dependency that includes a submodule, then dream2nix is fetching the dependency, it's not a flake input. I'm not clear how I could explicitly fetch a crate dependency, and tell dream2nix where to find that source for the sub dependency?