[gpm]

Right, that's usually described as "forwards compatibility", and yes, rust the language doesn't attempt to supply it. And yes, rustup is in fact a (the) solution for users. Distros increasingly package it because it is the recommended way to use the rust compiler (e.g. if you're on the latest ubuntu or any of its derivatives you can install it with apt instead of curl|sh).

A decent portion of projects, especially bigger ones, will try to support stables going back a few versions, but at best they're just changing the timeline slightly. This is really intended to help packaging for distributions, not users. Users should just use a compiler at least as up-to-date as the software they are trying to build.

[superkuh]

Exactly. rustc has a lifetime of about 3 months. gcc has a lifetime of about 5-10 years. Perl's interpreter has a lifetime of about 20 years.

edit since I can't reply: The difference is that Perl devs don't immediately use the new features (and Perl 6 is not Perl). Bash too constantly gets incompatible (forwards) changes, but no Bash dev is so inconsiderate as to use these as they want their software to actually run on people's machines.

That's my entire point: rust's immature/bleeding edge dev culture causes the problem. rustc could be okay, but the culture is too bleeding edge for using rust software now. Maybe in a decade it'll settle down.

[gpm]

Perl 5 introduced forwards incompatible changes less than a year ago. Perl 6 was so backwards incompatible that after 20 years of work they renamed the language to something else - it last had forwards incompatible changes sometime in january.

Not only are these not meaningfully better, they're also the opposite of what I would hold out as a "successful versioning model".

Rustc lasts until you are using software that depends on a more modern version of rustc, just like any dependency. Then you upgrade it - which just like any dependency with backwards compatibility - is painless (and in fact entirely transparent if you use tooling like rustup).