The Rust core team has released the stable version of 1.15, bringing with it the highly anticipated custom derive, allowing code-generating crates like Serde and Diesel to work ergonomically.
In the notes to RFC 1681 the motivation for custom derive is explained. Some large projects in the ecosystem today, such as serde and diesel, effectively require the nightly channel of the Rust compiler. Although most projects have an alternative to work on stable Rust, this tends to be far less ergonomic and comes with its own set of downsides, and empirically it has not been enough to push the nightly users to stable as well…
The good news, however, is that this class of projects which require nightly Rust almost all require nightly for the reason of procedural macros.
