I maintain a dozen or two Rust libraries and programs, and close to half of them are real-world production code. Exactly one of them requires nightly Rust, and

I maintain a dozen or two Rust libraries and programs, and close to half of them are real-world production code. Exactly one of them requires nightly Rust, and that's because it uses a feature (Macros 1.1) scheduled to show up in stable in just under 6 weeks. There are two reasons not to use nightly: 1. Stuff breaks. I remember the bad old days before Rust 1.0 and its iron-clad stability guarantees. I spent my time fixing a endless stream of GitHub issues reports across a half dozen projects. Modern nightly isn't so bad, but I'm still guiltily sitting on a PR about nightly breakage (as usual). But something that works in stable Rust just keeps working. 2. Stuff goes away. Nightly only features do get removed, and then you're stuck only building with an ancient nightly build.