When do Rust editions, such as 2015, reach end of life?

Question

Rust has different editions. The oldest edition is Rust 2015. The current version is Rust 2018. There is a planned release for Rust 2021. When will Rust 2015 be end of life and unsupported by rustc?

Answer 1

The official docs claim official editions will keep getting updates.

Compatibility

When a new edition becomes available in the compiler, crates must explicitly opt in to it to take full advantage. This opt in enables editions to contain incompatible changes, like adding a new keyword that might conflict with identifiers in code, or turning warnings into errors. A Rust compiler will support all editions that existed prior to the compiler's release, and can link crates of any supported editions together. Edition changes only affect the way the compiler initially parses the code. Therefore, if you're using Rust 2015, and one of your dependencies uses Rust 2018, it all works just fine. The opposite situation works as well.

Just to be clear: most features will be available on all editions. People using any edition of Rust will continue to see improvements as new stable releases are made. In some cases however, mainly when new keywords are added, but sometimes for other reasons, there may be new features that are only available in later editions. You only need to upgrade if you want to take advantage of such features.

(emphasis added)