title: How to install old version of rust-src?
body: <p>My machine have rust nightly-2020-03-24, I want to compile cross-compile crate core. But the command <code>rustup component add rust-src</code> install newest version of rust-src, which rustc-2020-03-24 can't build (due to new feature llvm-asm). How can I install old version of rust-src?</p>