build error

[sallyyu0]

Getting following errors today, Any ideas please?

Compiling lock_api v0.3.1 error[E0658]: use of unstable library feature 'iter_nth_back' --> /home/zzz/.cargo/registry/src/github.com-1ecc6299db9ec823/ipnet-2.1.0/src/ipext.rs:638:5	638	/ fn nth_back(&mut self, n: usize) -> OptionSelf::Item { 639		match *self { 640		IpAddrRange::V4(ref mut a) => a.nth_back(n).map(IpAddr::V4), 641		IpAddrRange::V6(ref mut a) => a.nth_back(n).map(IpAddr::V6), 642		} 643		}		_____^

= note: for more information, see #56995

error[E0658]: use of unstable library feature 'iter_nth_back'

... error: aborting due to 5 previous errors

For more information about this error, try rustc --explain E0658. error: Could not compile ipnet. warning: build failed, waiting for other jobs to finish... error: build failed

[krisprice]

Hi Sally, I recently merged in #13 of some iterator functions @TyPR124 contributed. To confirm this problem you’re having doesn’t occur if you set the version to use specifically 2.0.1 right?

[sallyyu0]

Hi krisprice, it happens as well. with version 2.0.1. And this just starting today. I'm wondering if any changes from compiler affected it.

[krisprice]

Can you check the version of rust you're using is 1.37.0 or later?

[sallyyu0]

it's 1.36.0

[krisprice]

nth_back was stabilized in 1.37.0, can you try updating to the latest version of rust? I think that will solve your problem.

[sallyyu0]

Right, I have 1.37.0 specified in Dockerfile so that works. But my newly built VM has cargo installed with older version. And I can't seem to update it to latest. How do I unsintall the older one before use rustup?

[krisprice]

That's going to depend on the OS you're using and its package management system, look into removing the default rust package that comes with your distribution, or look into using rustup to install rust in your home directory and just use that local copy. Let us know if you have any other issues come up. :smile: