[Pkg-rust-maintainers] Bug#1051501: Bug#1051501: provide subcommand that lists debian dependencies for a crate

[Fabian Grünbichler]

On Fri, Sep 08, 2023 at 06:50:22PM +0000, Jelmer Vernooij wrote:
> Package: debcargo
> Severity: wishlist
> 
> I've packaged a few Python packages that include rust code. Since they're
> python packages, I can't just use debcargo.  However, it would be great if I
> somehow use debcargo to extract Debian dependency information from Cargo.toml.
> 
> Perhaps a subcommand for debcargo that just dumps out a list of Debian
> dependencies and the features they are relevant for?

FWIW, there's both salsa issue[0] and a draft MR[1] open for this, the
former even predates this wishlist bug. Maybe something to finish over
the holidays ;)

FWIW, as a workaround, you can use debcargo's "local crate support" to
kickstart your d/control contents.

given a dir that contains a Cargo.toml file (let's call it "foobar"),
create a debian/debcargo.toml file with the following contents:

overlay = "."
crate_src_path = ".."

and add "debian" to the excludes in Cargo.toml:

exclude = ["debian/"]

(or add it an already existing list of exclusions)

now the following command will generate the debian dir like for a
regular debcargo-packaged crate, even if "foobar" is not published on
crates.io:

debcargo package --config ./foobar/debian/debcargo.toml --no-overlay-write-back --directory ./tmp-foobar foobar 0.1.0

FWIW, since this effectively calls "cargo publish" under the hood, it
has the same restrictions w.r.t. dependencies in Cargo.toml (no
unversioned deps except for dev-dependencies which are ignored, no
path/git deps except if they have a version requirement, ..).

0: https://salsa.debian.org/rust-team/debcargo/-/issues/56
1: https://salsa.debian.org/rust-team/debcargo/-/merge_requests/49