[Pkg-rust-maintainers] Packaging advice/help wanted for anki, which has just started using some Rust

[Julian Gilbey]

Dear all,

I maintain the Python-based package "anki", which has been almost no
problem up to now.  But upstream have just started incorporating some
Rust code into it, and I've never used Rust myself.  The build
mechanism they have written involves downloading and compiling Rust
modules (I think that's what it's doing) using rustup.  Here's a piece
of the Makefile as an example:

# nightly currently required for ignoring files in rustfmt.toml
RUST_TOOLCHAIN := $(shell cat rust-toolchain)

.build/tools: requirements.txt rust-toolchain
	pip install -r requirements.txt
	rustup toolchain install $(RUST_TOOLCHAIN)
	rustup component add rustfmt-preview --toolchain $(RUST_TOOLCHAIN)
	rustup component add clippy-preview --toolchain $(RUST_TOOLCHAIN)
	@touch $@

.build/check: build
	cargo fmt -- --check
	cargo clippy -- -D warnings
	@touch $@

(This is a little weird, as there's no rule to make rust-toolchain.
Perhaps an error in the Makefile?)

So any advice on how to handle this?  There is no "rustup" package in
Debian (presumably for a good reason), but I have found the list of
available rustup components here:
https://rust-lang.github.io/rustup-components-history/
Is there any way to do this process within the existing Debian Rust
infrastructure?

Also, is there a Debian Rust Policy?  I haven't been able to find one
on a quick scan.

Many thanks,

   Julian