How fast can one realistically expect to be able to build decent quality system-level rust code, provided the person is already familiar with C-style programming languages and has 0 rust experience ?
> All survey participants are professional software developers (or a related field), employed at Google. While some of them had prior Rust experience (about 13%), most of them are coming from C/C++, Python, Java, Go, or Dart.
> Based on our studies, more than 2/3 of respondents are confident in contributing to a Rust codebase within two months or less when learning Rust. Further, a third of respondents become as productive using Rust as other languages in two months or less. Within four months, that number increased to over 50%. Anecdotally, these ramp-up numbers are in line with the time we’ve seen for developers to adopt other languages, both inside and outside of Google.
> Overall, we’ve seen no data to indicate that there is any productivity penalty for Rust relative to any other language these developers previously used at Google.
That should get you started to writing decent code, maybe not aways idiomatic or neatly structured. That might take a few more weeks or months (depending on your interest domains and their inherent complexities). But like with all skills, it's an endless journey; you'll keep getting better as you're increasingly more familiar with the tools.
For ABI Rust has an explicit way to say "Lay this out the way C does" which works for things that you could have done in C. How is everything else laid out? Not your business. So again, your C expertise applies.
Neither Rust nor C formally have agreed pointer provenance rules, if you've learned things that are promised to work in this domain in C most of them also work in Rust. Most things aren't promised to work in C, Aria's Strict Provenance experiment and associated APIs are more than you're going to get from ISO C any time soon.
Aliasing rules are stricter in Rust than C, but also I'd argue much simpler. So that seems not to be a huge amount of extra work.