Re: Rust and Q-branching

[Jonathan Perkin <jperkin%joyent.com@localhost>]

* On 2021-09-03 at 13:10 BST, Greg Troxel wrote:

> It is really unfortunate that the rust world thinks it is ok to depend
> on really recent rust.  1.54.0 was only released 36 days ago.  So
> separately from our stability concerns about updates close to freeze, I
> don't think it's a problem to defer those updates until after branching.

I know I'm biased in favour of Rust, which may cloud my judgement, but I 
think it's important to realise that software in general is moving 
towards more frequent releases and a more aggressive expectation of 
things being up-to-date, and it's just something we're going to have to 
deal with or be left behind.

Rust developers and users primarily use "rustup" to handle their 
toolchain, and will generally switch to the latest version with a simple 
"rustup update" on the same day it is released.  When you're used to 
that workflow, it's unfortunate, but 36 days feels like an eternity.

In terms of Rust releases, other than having to produce the necessary 
bootstraps, this should not in theory affect any package builds.  Rust 
has a very strict notion of "editions":

  https://doc.rust-lang.org/edition-guide/editions/index.html

so if there is some software that builds ok on rust 1.N but not 1.N+1 or 
even 1.N+47 then that is a bug in that software, i.e. it hasn't 
correctly specified which edition it is targeting.

That of course doesn't excuse drive-by updates, and we should be as 
careful as possible, but it should mean we can be more confident that as 
long as Rust itself builds on all important platforms we should be good 
to go, at least compared to some other languages.

--
Jonathan Perkin  -  Joyent, Inc.  -  www.joyent.com