[bsaul]

Not sure if that's still the case, but Graydon Hoare was part of swift team. Swift also slowly introduces support of lifetime analysis with regards to concurrency, but the path they chose is pretty different : they started with an easy to use language, and moved toward advanced concurrency-related security features, trying to keep the language convenient. Rust went the other way.

This makes a lot of sense considering swift's primary target: app developers that build end-user facing software, as opposed to core system developers for rust.