Summary

Move the contents of std::thread_local into std::thread. Fully remove std::thread_local from the standard library.

Motivation

Thread locals are directly related to threading. Combining the modules would reduce the number of top level modules, combine related concepts, and make browsing the docs easier. It also would have the potential to slightly reduce the number of use statementsl

Detailed design

The contents ofstd::thread_local module would be moved into to std::thread::local. Key would be renamed to LocalKey, and scoped would also be flattened, providing ScopedKey, etc. This way, all thread related code is combined in one module.

It would also allow using it as such:


# #![allow(unused_variables)]
#fn main() {
use std::thread::{LocalKey, Thread};
#}

Drawbacks

It's pretty late in the 1.0 release cycle. This is a mostly bike shedding level of a change. It may not be worth changing it at this point and staying with two top level modules in std. Also, some users may prefer to have more top level modules.

Alternatives

An alternative (as the RFC originally proposed) would be to bring thread_local in as a submodule, rather than flattening. This was decided against in an effort to keep hierarchies flat, and because of the slim contents on the thread_local module.

Unresolved questions

The exact strategy for moving the contents into std::thread