Rust 1.40
The continuing improvements to procedural macros are great!<p>I do a fair amount of integration with C, and the work the rust team is doing for procedural macros has helped <i>a lot</i>. Being able to use them in an extern blocks will surely help more.<p>Like many, I have a wish list that I complain about sometimes, but I feel bad about complaining because rust has done so much to improve my use case I don't know where to begin. I should write up a blog post about all of the difficulty I had, and how each release since around 1.28 has introduced features that solved these problems one by one.<p>To me, Rust/C interop is the killer feature. Not only is it a low-level language that can be used instead of C, it can also be used to <i>extend</i> C applications. I'm sure it was not easy to do this well, but what a great strategic decision by the rust team to spend the effort on it!