[Libguestfs] Cargo edition problem with Debian 11

[Richard W.M. Jones]

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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