non-escaping functionsの変遷を簡単に解説してる。 https://twitter.com/slava_pestov/status/1085691914328920066 (ツイート内のリンクは上記PR) (edited)

Short history of non-escaping functions:

Swift 4.1 and earlier: type checker enforcement; same ABI as escaping
Swift 4.2: new ABI - the context is a trivial pointer and not ref-counted like with escaping
now: non-escaping contexts allocated on stack https://t.co/gIl...