There's a merged pull request on the void-packages repository

Rust 1.40
https://github.com/void-linux/void-packages/pull/17684

Description:
Testing:

- [x] x86_64
- [x] x86_64-musl
- [x] ppc*
- [x] aarch64(-musl)
- [x] armv7l(-musl)
- [x] Firefox builds

Depends on https://github.com/void-linux/void-packages/pull/17671