[Libguestfs] Cargo edition problem with Debian 11

[alan somers]

IMHO this is a design bug in Debian.  Sure, they need to create
packages for any Rust crate that needs to install executable or .so
files.  But crates like nbdkit don't install anything.  They're only
used to build other Rust crates, and only used at compile time.  They
can simply be fetched during the package building process.  I really
don't know what Debian is doing by packaging this crate.  Is it
actually trying to install the ramdisk example?

On Fri, Jan 13, 2023 at 7:27 AM Richard W.M. Jones <rjones at redhat.com> wrote:
>
> On Fri, Jan 13, 2023 at 07:17:14AM -0700, alan somers wrote:
> > I think we should downgrade predicates-tree to 1.0.5 or older.  I can
> > submit a PR for that.  What does "rustc --version" show you?
>
> Unfortunately our configure script doesn't collect that information
> (it should do! - I'll fix that in a moment).
>
> But based on it being Debian 11 ("bullseye") it's likely to be:
>
> https://packages.debian.org/bullseye/rustc
> Package: rustc (1.48.0+dfsg1-2)
>
> Which is pretty ancient ...
>
> Rich.
>
> > On Fri, Jan 13, 2023 at 2:41 AM Richard W.M. Jones <rjones at redhat.com> wrote:
> > >
> > >
> > > https://gitlab.com/nbdkit/nbdkit/-/jobs/3598390121
> > >
> > > ----------------------------------------------------------------------
> > > cargo build --release --example ramdisk
> > >  Downloading crates ...
> > >   Downloaded float-cmp v0.9.0
> > >   Downloaded downcast v0.11.0
> > >   Downloaded mockall_derive v0.11.3
> > >   Downloaded itertools v0.10.5
> > >   Downloaded aho-corasick v0.7.20
> > >   Downloaded predicates-tree v1.0.7
> > > error: failed to parse manifest at `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/predicates-tree-1.0.7/Cargo.toml`
> > > Caused by:
> > >   failed to parse the `edition` key
> > > Caused by:
> > >   this version of Cargo is older than the `2021` edition, and only supports `2015` and `2018` editions.
> > > ----------------------------------------------------------------------
> > >
> > > nbdkit itself uses edition = 2018, but this seems to affects one of
> > > the dependencies.
> > >
> > > I'm not sure how to solve this, but one ideas I had is in ./configure
> > > to check if the cargo/rust we're trying to use doesn't support some
> > > base edition (eg. latest edition supported < 2021) then we would
> > > disable rust bindings.
> > >
> > > Unfortunately actually getting the latest supported edition seems
> > > hard.  The best I could find is parsing this which doesn't seem ideal:
> > >
> > > $ rustc --help |& grep -- --edition
> > >         --edition 2015|2018|2021|2024
> > >
> > > What do you think?
> > >
> > > Rich.
> > >
> > > --
> > > Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> > > Read my programming and virtualization blog: http://rwmj.wordpress.com
> > > libguestfs lets you edit virtual machines.  Supports shell scripting,
> > > bindings from many languages.  http://libguestfs.org
> > >
>
> --
> Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
> Read my programming and virtualization blog: http://rwmj.wordpress.com
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>