Sync from rust c9228570668803e3e6402770d55f23a12c9ae686
Sync from rust c9228570668803e3e6402770d55f23a12c9ae686

graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust