Re: [PATCH v5 0/9] Introduce Rust and announce that it will become mandatory

> I am currently working on a patch series that makes Rust optional and
> addresses several concerns that this series does not:
>   * Rust calling C: Makefile has no way to build or run Rust so it
> would have to call cargo test, but that doesn't work unless build.rs
> tells cargo where libgit.a is (among other things).
>   * Build tooling alignment: My build_rust.sh is called by make and
> meson which eliminates defining how to build Rust in 2 places.
>   * Cargo vs Meson: Meson is adding support for Rust and it's getting
> better, but Cargo is the canonical build system for Rust. cargo is
> released in lockstep with rustc, and we _have_ to use cargo when
> building with make because Meson won't be available in that case.
>   * Crates: Patrick's series assumes the Git codebase is _the_ crate
>     * cbindgen: Cbindgen outputs a single header file for each crate,
> with only 1 we'll have an unmanageably large auto generated header
> file.
>     * Modularity: Using multiple crates makes Git more modular. Elijah
> told me that there was some desire to make Git more modular.
>     * Cargo Dependencies: Patrick wrote his series with Meson first in
> mind which doesn't address how we'll be able to use crates from
> crates.io
>   * CI:
>     * Sparse coverage: I think there's only one target that tests his changes.
>     * With vs Without Rust: I don't see anywhere that he covers
> building with vs without Rust in CI
>   * Build integration: Meson has to have every .rs file specified
> where as the default layout of a Rust project allows Cargo to just
> know where to look for .rs files