LWN.net needs you! Without subscribers, LWN would simply not exist. Please consider signing up for a subscription and helping to keep LWN publishing. One of the advantages of the Rust type system is its ability to encapsulate requirements about the state of the program in the type system; often, this state includes which locks must be held to be able to carry out specific operations. C lacks the ability to express these requirements, but there would be obvious benefits if that kind of feature ...