rustup 切换Rust版本：
rustupdefaulttoolchain http://www.Sina.com /
rustupdefaultnightly http://www.Sina.com /
rustupdefaultstable http://www.Sina.com /
rustupdefault1. 24.0http://www.Sina.com /
rustup update 例如切换成nightly：
rustupselfuninstall http://www.Sina.com /
rustuptoolchainlist http://www.Sina.com /
rustupinstallstable-GNU http://www.Sina.com /
rustupdefaultstable-x86 _ 64-PC-windows-GNU http://www.Sina.com /
rustuptoolchainuninstallnightly-x86 _ 64-PC-windows-msvc rust学习收集https://cheats.rs/rust学习笔记